Editing Building Chevy 4.3 liter V6 - 1994 with balance shaft

[[Category:Engine|B]] == LAST EDIT == 15 DEC 2017 update - rotating assembly is ready. 15 SEP 2017 update - had the crank finished and readied for nitriding 15 AUG 2017 update - finally the pistons from JE arrived. Test assembly 12 JUN 2017 update - still waiting for the pistons nothing else done :( 26 MAR 2017 updated - test assembly 27 OCT 2016 updated - valvetrain 27 FEB 2016 updated - measuring up 16 FEB 2016 updated - heads disassembly 21 JAN 2016 started - disassembly I had a 1994 Chevrolet 4.3 Liter V6 sitting at my place waiting for rebuild and tune. Actually it is in single pieces right now in the midst of the project. I'll use this article to describe, report and evolve on this project to have one single place where to reference to in the various forums I'm a member. Please refrain from simply editing, instead leave your comments and ideas in the discussion section so I can correct my text and integrate your input (with reference to your contribution) to keep the text neat and clean and "in one casting". I'm editing the text in a file I have on my computer and usually replace all the text in the wiki with the latest version i wrote. Thanks ---- == LIABILITY WAVER == A bit of a warning and a statement about liability. I am not a trained mechanic. All advice given is to the best of my knowledge and I will normally point out where I'm not sure of my actions or cannot back it up with experience or advice from others. I will not be liable for anything be it information given herein nor advice or procedures I describe or use. It will be ALL AT YOUR OWN RISK. '''MY HISTORY - NICE TO KNOW''' Having said this you may want to know why you may continue reading the stuff a guy writes up which is not even a mechanic. Have a look at my profile. ---- == PROJECT GOAL == This shall become a daily driver able to tow and remain emissions legal. That means no fancy exterior bolt-ons, no crazy camshaft, no crazy horsepower, needs to remain within emissions with catalytic converter. '''WHAT IS PLANNED''' I can throw a bit of money at it and do all the stuff except for machining myself. The budget is 7'500 $ to start with with a bit of allowance for better parts. I can keep the machining in reasonable limits as I know the guys well and can help with the time consuming stuff. == TECH STUFF ABOUT THE 1994 4.3l V6 - VIN Z (TBI fuel injection) == Apart from having many similarities with the small block there is a couple of things that are not well documented in the forums about this engines more advanced, more modern features. '''HEADS''' There is a particularity here! GM in the years around 1990 has started to adopt the metric system for some applications. Some threads may be metric. Should you ever come to find a bolt hard to fit check threading. In particular the screw in studs on 1995 and later may be metric M10 x 1.5's from factory or the smaller M8 threads. Some ARP aftermarket studs have this threading as well. Heads have stamped rockers, pinched nuts on pressed studs. This will definitively be one of the mods. At the moment I'm trying to figure if the heads correspond to L05 heads of the V8. They already feature the "ski-ramp" swirl ports (vortec) but not yet the kidney shaped combustion chamber. Further study and evidence indicate that I'm right on classing these heads. They do not flow terribly but should do the job. The only figures I came by for the exact casting numbers are low figure at 135 cfm and a higher number at 180 cfm. '''BLOCK''' Nothing particular there. A couple of threaded holes are not used according to the vehicles type and RPO's. It seems that this is an engine still based on the GEN I smallblock cast iron block. It normally has only 2 bolt main caps. '''CRANKSHAFT''' The crank is a cast, even fire crank and has standard mains as a V8 small block but has bigger rod pins at 2.25" diameter. Unfortunately this excludes a lot of aftermarket rods from the list. The last main bearing, oil pump attachment etc. are also the same as a 350 SBC. '''RODS''' The rods are of standard lenght 5.700" but have larger big ends. Some confusion exists in the aftermarket as some manufacturers offer rods for the 4.3l V6 years from 1988 - 2007 but indicate 2.125" big end bores (crank pin diameter) which is not correct for the even firing engines. The piston pins are press fit (into pre-heated rods) and will be changed to full floating. '''PISTONS''' I found standard cast pistons with a dish measuring some 20 cc's with four valve reliefs and a notch. They will be replaced with forged flat top's and two reliefs. When measuring we found out that they are an additional 0.85 mm (0.033") below deck. The piston pin is 1.6 mm (about a 1/10") out of the center of the bore to reduce piston "slapping". '''OIL PAN''' The 4x4 has a very deep oil pan. In order to clear the front axle the deep portion of the pan is shorter but taller. '''CAMSHAFT''' It has a hydraulic roller camshaft with the stepped nose and the retainer. This is a benefit for the build as "cam-walk" is no issue. '''LIFTERS''' This has come to a surprise. It employs a plastic retainer along the full side of the lifter valley. One left, one right whith two bolts each fixed down into the block. We'll see what to do of it. Seems a nice and easy way to keep the lifters where they belong. It has some oil holes and a lot of small fins that are for oil drain flow. I'll add more stuff as I go and discover what is particular or what differs largely from a standard pre 1988 small block. ---- == 2016-JAN-21 TEARDOWN == Teardown has started. The major challenge was to get the engine from where it was sitting at a friends warehouse to the garage where I work part-time for the teardown into handy pieces. All the work which can be done by myself will be done at my place where I have a room for such work. As it lays in a basement it is a bit of a hassle to get the engine there. For the further work I will always handle the disassembled engine (handy size and weight of parts). The final assembly will again be done in the garage which is outfitted for engine assembly. A properly drained engine will be worth gold once you start to tear it down. There is no mess, else an engine stand is mandatory with a large pan underneath. No surprises once I had it on the bench. The first thing I did was spray all bolts that I saw with a penetration oil, then went for lunch. Removed all stuff from the TBI, sensors, ignition coil TPI, EGR and other stuff. Removed all the small vacuum lines, the large ones, the supports for the various stuff on top, unplug all sensors and then remove the complete wiring from the top of the engine. I have some 100 re-sealable plastic bags handy, tags that can be tied to pieces and an indelible EDDING pencil. I store the stuff as I go and I clean up the worst of dirt and oil before bagging and labeling things. It may seem silly but I also add special observations on the bags such as location of specific fasteners or pieces, clips and such. What seems obvious now ("Ahh - You know where you have removed that support from") may not be so obvious in 6 months when it is assembly time. The next step is storing in cardboard boxes for transport. At my place in due time I will pick a couple of bags and start rebuilding stuff or make a list of what to order. During the process I have kinda three piles of stuff: Fine to be re-used / Rebuild or order / Trash. Once nearing completion I want an inventory of only Fine to be re-used and Trash as that means I have all parts ready for final assembly. '''TBI''' Next is the TBI, carefully remove all plugs and sensors. It's easier to remove them as long as the TBI is still attached to the intake manifold. Then remove the 3 bolts of which 2 are special ones and detach the TBI body from the manifold. '''MANIFOLD''' Loosen all bolts from the intake manifold and detach the remaining supports for various stuff, pre-clean and label. Then remove all the intake manifold bolts. A couple of light taps at the corners were enough to crack it loose despite the block having rusted quite a bit. All sheet-metal supports have rusted, some even rusted away completely. Remove the manifold, pre-clean and store. (Will be checked, cleaned, ported and finally painted in the process.) '''STUFF ON THE BLOCK''' Then I got rid of the engine mounts, lateral sensors of the block on the accessible side. Depending on how you disassemble you may also remove the other sides stuff such as the other mount, oil level dipstick and such. '''HEADS''' The 1994 engine has solid plastic covers with three retainer bolts. These are very special bolts, apart from that no surprises. As they have a rubber seal they crack loose when hit with the flat hand on one side. Now we have access to all the rockers. To just pull the heads (I will tear them down later at my place - for now it is just to get handy pieces) No need to remove all the stuff such as rockers, retainers, valves... I have switched to an air tool (as I have access to it) but it would be possible by hand as well. Loosen all the retainer nuts on the rocker arms. Leave them tightened a couple of threads on the studs so the rockers stay with their respective valves. I would recommend this as well for repairs. No need to take them all off, because when reusing them you have to keep them in the exact location from where they came. They break in to their respective pushrod and valvestem. Once loos you can simple lift them a bit and turn a couple degrees to free the pushrods. I took a 10 x 30 cm piece of cardboard and folded it in half. Then punched 6 holes x 2 into it where to stick the pushrods. Marked it accordingly (cylinder head left or right from front to rear and up and down, where down is in the lifter valley. (Oh - the 10 x 30 cm makes about 4 x 12 inches.) Still with the air tool (you will need a decent 1/2" wrench at least 40 cm (18") long to crack them open, and following the tightening order (I know, not necessary for disassembly - but still...) loosen them. As I had the engine on the bench and laying to one side I left the two outer (exhaust side) bolts in by a couple of threads to keep the heads on the block should they come off while removing all the bolts. No need to have them nick my bench, feet or floor. Then tapped them with a plastic hammer (a bigger size now) on the four corners a little bit with one hand on them and I felt them separate quite nicely. Once you are positive that they still sit on the centering pins, remove the two remaining bolts and lift them off. And now the other side - same, same. '''FLEXPLATE''' Six bolts (air tool again), then wiggle it off or use an appropriate puller. Just make sure, the engine is supported in a way, that the flex plate is not bearing any load of the block. '''OIL PAN''' The oil pan has four larger bolts in the corners, three special studs(bolts) on one side and a couple normal bolts for the rest. Two metal inlays serve as washers on the full length of the oil pan. In order to remove them I had to unbolt and remove the attachment for the remote oil filter hose from the oil pump outlet outside of the block. (This is a 4x4 version VIN Z engine). Tap it with your flat hand it should break loose quite easily. When removing pull it up slowly and gently. It will get stuck on the oil pump pick up which is nested through the slush guards inside the oil pan. It will need a bit of gentle movement fore and aft to clear the pick-up screen. And now we're at the crankcase. '''CRANK AND CRANKCASE STUFF''' The first thing to note is that the 1994 VIN Z engine has two bolt mains. That means the main caps have only two bolts a piece. The next oddity I noted is with the numbering of mains and the rods. The mains have an arrow pointing forward and all different casting numbers but no specific locator or identification. So I will see where to add one with my machine shop. The next thing was the rods as I found the letters F-F, J-J, G-G stamped on them. Seems they are paired. Will see tomorrow what the logic is. As I want to keep them exactly in location I will number them as well to keep the sets properly together. == 2016-JAN-22 - TEARDOWN, THE REST == After all the stuff has gone from the block I'm left with the rotating assemblies. Crank, rods, pistons, camshaft and balance shaft. I had to take the engine apart for transportation reasons. Needs to go up and down a steep ramp (next to a stair) so I'm not going to pull a 300 lbs engine into my place. To have it even more handy I'll now take the rods, pistons and the crank out of the block. '''OIL PUMP''' Now I removed the oil pump to get it out of the way. one center bolt is connecting it to the block. Carefully pull it out straight as the shaft is some 20 cm long (8 inches). Place it in a pan or your old oil drain as it may still contain some engine oil. '''MARKING''' Got 6 nice sized clear plastic boxes and some more boxes with separators and a lid from IKEA to store all the stuff which will come out and not mix it up. Marking will be done with the EDDING water resistant pencil on a cleaned and degreased surface (brake cleaner on a rag). As the block is upside down I first figured correct location of the cylinders. Left is odd, right is even. Number one is in front left also where the cam drive sits. Then wrote the cylinder numbers down on the freeze plugs which were the only places without rust or oil. I've used the harmonics damper loosely put on the crank snout to turn the engine over. If it does not turn easily by hand you're in for a heavy rebuild anyway. Mine turned just fine with a bit of resistance but could be turned with one hand. Place the rod you want to split into a convenient location where you can set the wrench and break the nuts loose without hitting your hands on the sharp edges of the crank. I normally write a little legend on the workbench (aluminium sheetmetal cover) for the nuts position and the rest. As I do not know at this point what I will do to the engine and don't go into the hassle of remembering all the stuff that has to be marked with position and direction of assembly I simply mark everything. A rag with cleaner I search for a convenient spot to mark the rods, wipe the oil and dirt off and mark it with the cylinder number. I also mark the forward position with an arrow and a 1 and 2 for the bolts and nuts. Mark the cap and the rod with matching cylinder numbers. Ever had your cat stray into the garage and push a box with stuff over.? Then try to match parts. In general the rods and crank and stuff are marked by the factory but they tend to use funny ways. My rods are marked F-F or J-J but then I found that three where marked F-F. So I'm not going to take chances on that. '''ROD AND PISTON REMOVAL''' Loosen the rod bolts but leave them on at least a couple of threads. Gently tap one of the two bolts with a plastic hammer. The rod should split right away. Because the bolts are still in place it will not fall into the depths of the crankcase, cylinder bores. Now remove the nuts carefully. Hold the rod part with one hand and with the other wiggle a bit on the rod's cap. They should come out easily with a slight pull. Sometimes residual oil will cause a bit of suction/adhesion on the bearing surface. Try to pull it straight or it may bend between the two bolts. Original bolts are kind of forced into the rod and will not fall out. Aftermarket may fall out, one of the reasons I at least hold the upper (long) portion of the rod where I can get my hand in to avoid it slide down or the bolts to fall out. If they do - use a magnetic pole or flex handle to pick it up. Do this anytime something falls down. Search as long as it takes to find and remove it. If you turn the engine for the next cylinder you can nick the cam or crank or a bearing surface with the bolt somewhere in the depths of the engine. Lay the parts aside on the legend of the workbench. The lower part of the rod bearing can stay attached to the crank. Leave it there as it is nearly impossible to get it out. It will stick to the crank due to residual oil. Once the piston is out you can easily pick it from the crank. The piston rings should have enough resistance that the piston will not fall out. Normally it should take a little push to move it up in the bore. Actually moving down, as the block is upside down now. Push the piston down by pushing on one of the bolts with your thumb, so you can leverage with the remaining fingers on the edge of the block. It will most of the time move down until the compression ring (aka the first ring on the piston from the crown) hits the cylinder wall where the rings do not run. This is in most cases an area some 3 - 4 mm (a little less than 1/4") on top of the cylinder bores. There is no abrasive force so it creates kind of a step a few thousands less in diameter than the cylinder bore where the pistons run. Think of how you can center the rod in the bore, tap it with an adequate tool to move down and once it slides out (actually falls out) catch it! Have somebody help you or as was my case with the block upside down on a flat space the piston will just fall 5 cm (2 inches) and lay on the table. Put some cardboard underneath to soften the fall and catch residual oil dripping from the piston and bore. To get it out the trick is to suspend the rod with one finger from the bolt and position it in the center of the cylinder bore in order for the rod not to touch the lower skirt of the bore and get stuck. The upper portion of the rod bearing is normally still in place in the rod. It is cramped in the bore despite the 4" bore. I use the plastic hammers handle (wood) after making sure that the end is round and has no protrusions from stuff embedded in the wood. Then try to tap slightly on the piston pin bossed or if that is not possible on the rod. Another possibility would be to remove the upper rod bearing and tap it in the rods bearing location. Put all together in the correct location and stored the pistons with rings, pin and rod with cap, bolts and nuts assembled loosely in the boxes I had prepared. '''WARNING!''' Light tapping should be well enough to have the piston slide out. If you hit resistance re-check your rod alignment with the bore. When dealing with really old engines with many many miles check the ridge on top of the bore. Check the bores for rust. If all fails it may be necessary to carefully push the rods and pistons up (towards heads) as much as possible and remove the crank first to pull the pistons out of the bores below. You may have to loosen all the bolts, remove the outer ones in order to be able to access all the inner ones with the crank in a horizontal position, then remove all the mains and pull the crank. Or maybe the best advice is to ask your machine shop or take the block to the shop right away. If ridges are found to be the obstruction it may be best to ask your machine shop to remove them. '''CRANK REMOVAL''' By removing the crank and the main bearing caps I can put the block back upside down and it will rest on the deck edges nicely for transport. Be sure to place the block that way only on clean surfaces possibly with a piece of board underneath as it is standing on machined surfaces. To remove the crank, crack all the bolts on the caps and remove them. I again kept them in the order I have removed them from. Clean and check the bearing surface. The crank has no discolorations which is a good sign. Seems that it never overheated somewhere. The bearings show normal wear for a 120'000 miles engine. Once all the caps were off I found one with a scratch through about 100 degrees of the lower half of the bearing. The small debris embedded itself into the soft bearing surface and did not scratch the crank too badly. A bearing is supposed to do exactly this - embedd debris into the soft layer. This is one of the reasons for a soft surface. Packed all neatly into the boxes and two large cardboard boxes and transported it home. == 2016-FEB-12 - DISASSEMBLY, HEADS AND BLOCK, CLEANING == Taking the heads apart was easy with the appropriate tools. Valve spring compressor and a magnetic pick and valves are out of the heads within 30 minutes. Took the block and heads to my shop where they pulled the plugs. Some of the freeze-plugs had already started to leak from corrosion which hat eaten through from inside. Then had block and heads hot tanked. I gave them a thorough wash with the pressure washer. Then cleaned all with brushes and parts cleaner at the shop. All color is removed from the block as well as all the sooth from where it could be accessed. Brushed out the runners with a compressed air tool and a fine metal brush. Then took a grinding stone and got rid of all the casting ridges and brows. Chamfered all sharp edges taking care not to damage any seal areas. == 2016-FEB-27 - MEASURING FOR BLUEPRINTING == ''' CAMSHAFT ''' The camshaft has measured differences between the intake and exhaust cams of up to .52 mm (0.02 in) differences in lobe lift vs. base circle from one lobe to the next. Also the base circles differed by 0.4 mm (0.015 in). The COMPCams cam has an equal base circle and lobe lift on intake and exhaust. (BTW measured not only where the roller of the lifter runs but also at the edges of the cam. Also make sure you understand the various lobes as they are in a specific order of intake and exhaust lobes. The bearings are pressed into the block and have an oil hole each which needs to be aligned properly with the blocks delivery holes. == 2016-OCT-27 - VALVETRAIN MODS == ''' ROCKER STUDS ''' Pulled all the studs and my friendly machine shop had the bosses cut about 0.050" (1 mm) in order to get a nice flat starting point to cut 7/16" UNC threads. Later found out that with roller rockers I need to cut the bosses back an additional 1/4" to get the geometry right. Found 16 TRW screw in studs and have machined the collars for guide plates off, then checked valve geometry with the intended rocker arm. It will need more machining to match the correct geometry. At the same time found that I will have to machine an aluminium spacer for the OEM valve covers. It has to be about 20 mm (0.75") in order to clear the rocker arms inside of the original plastic valve covers. More stuff to do. == TIPS AND TRICKS == Drain the engine oil with engine hot. Or maybe place the engine close to a heat source or at the sun to heat up while draining. Maybe even a couple of days. Especially the water will still pool. By placing the engine at different angles you may drain most of it. Once the heads are off some coolant may drain when turning the engine over from the passages in the back between block and heads and from the two located between the first and last and the middle cylinders. It is so much easier without the mess of oil and water on your workplace. Spray all bolts with penetration oil and let it soak. Re-spray after 30 minutes or spray before heading out for lunch. Spray the gasket edges e.g. TBI, Thermostat, sensors, head-gasket as well. I nearly always wear surgical gloves when working on dirty stuff. At the same time these gloves save you from fine metal filings which can sting through the skin. Use the "nitrile" ones as latex will dissolve in most of the fluids we have around engines. Marking parts is easiest using an engraver such as one from DREMEL or others. Just got one a couple days ago for 40$ and works like a charm. Try to etch your marks in locations where they do not add a stress raiser. Where original factory markings are located could be a good spot or check on the internet or books. All machined parts which touch another part is no-no. All surfaces where a bearing is being set are no-no unless treated accordingly. Try finding spots where there is no gasket. On the heads for example is a lot of room on the intake side surface where there is no gasket. Engravers stamp little craters into the metal. By sanding over it with a fine grit paper or a stone can relief the sharp craters rims and allow for a gasket to sit on the marking without leaking. Put an engine together in a hurry and sloppily and it will leak and wear. Cleanliness is not an option but a MUST on the workplace. I do not assemble in the same location where I grind and sand. I've disassembled a big block which has been killed because somebody had sanded the intake. The little bit of remaining grit which had not been washed out properly killed the new engine in 100 miles. After 100 miles it had used 2 quarts of oil - no leaks - but everything was scratched and scored. Result - rebuild with all new bearings, new hydraulic lifters, new pistons and rings, new valves, with a bit of luck no new valve guides and a hone on the cylinders. For analysis we had it disassembled and one piston with the rings still on washed out into a glass plate with thinner. Once dried we placed it under the microscope to find a "beach". We found glass particles, sand particles of various color and the nice diamond shapes of corund. The rings had been sanded and were showing the wear normally associated with 300'000 - 400'000 miles of engine life! So any sand is a big no-no near my engines. == ENGINE STAND == Engine stands for U.S. engines are not readily available in Europe and very expensive to have them shipped. I opted for a build based on two 400 kg (some 850 lbs) dollies with four free steering wheels and brakes on two. A couple of scaffolding tubing and joints for some 180 $ make a nice and rather solid stand. I'll have a friend cut a steel plate to match the holes on the engine transmission side. Then I may be able to turn the engine on two axis. Could be handy to store the block on the stand. The block has been disassembled completely now, the lifters are out, everything except the crankshaft looks reasonably well in shape and could be reused right away. No surprises so far. The block is clean and dry now, the heads as well, all the stuff is out and shows reasonable wear. Above the lifter valley things look good. No scratchings as in the lower side. Camshaft looks good as well. Hot tanked and washed I ground all the casting ridges down and smoothed some of the sharp edges and corners on the block and heads. No more cuts from the heads and block. Talk to your machine shop where this is safe to be done and where not to touch the surface. In general all machined "surfaces" are no-go with the grinder. All external casting ribs and sharp machined edges are o.k. to get a slight chamfer or being deburred. Easy on thin surfaces that should seal such as the timing covers or the valve covers ribs on the block and heads. == NEXT STEPS == Valvetrain geometry will be next I will have to see if 1.6:1 rockers will fit with a cam at some 0.48 to 0.50" lift at the cam. With the flat top I need enough clearance. I'll retain the original valve diameters of 1.94 and 1.50 inches for good vacuum in the manifold and high speeds in the runners for torque. I have checked with an engine builder close by which has just built a CHEVY big block using CompCams stuff on the heads. I'm on the right path. He used comps magnum pro steel roller rockers. Nice and neat for a 6'000 rpm redline engine. The next thing will be the geometry. There is a slight splay of angles between the centers of the pushrod holes, the studs and the valves. The splay may require guide plates which should be no issue with the screw in studs. Have to measure these next. Also the guide bosses have to be machined to proper height. To achieve the proper valvetrain geometry I may have to buy the rockers first and then machine for screw in studs. So I can do minor changes to the centers and heights and align the studs properly. Looks like the heads will have the pressed studs removed and replaced with screw in studs and the valvespring pockets will be machined as well as the stud bosses to get good seating for springs and studs. The seat height at the moment is nice. The difference measured over the valves tips is less than 0.01" (0,1 mm). Exhaust valves protrude a lot more into the combustion chamber due to thicker material which adds to compression. The decisions about the seat cutting can be done only after I have the proper geometry figured out. To get some basic figures I have to put a head onto the block and use clay to see what valve clearance is based on the OEM camshaft. Waiting for the pistons. == THE PARTS == One of the downsides of this engine is the fact that nobody seems to take an interest in serious builds on this base. Although this engine has seen a myriad of applications and has been produced in millions it has never been seriously considered for racing or builds, except for some bracket race or dirt track cars. It shares a great deal of common parts with the SBC V8 so a lot of parts can be sourced from there. The hot-rod magazine has probably built the ultimate 4.3l V6 showing the potential. Here is the experience with the various important parts of the build: '''CRANKSHAFT''' Cranks are available as cast cranks for as little as 150 $. For a more serious build a forged crank would be nice. All the OEM cranks including those used on the marine engines producing 200+ hp are cast cranks. All the V6's are external balance cranks. The cranks weighted in at 18.9 kg (41.7 lbs). Most suppliers would supply a billet crank for this engine from 3'000 to 5'000 $. The problem is: Then you have a monster crank able to withstand 1'200 hp in a two bolt cap block able to withstand a mere 400 hp at max. '''MAIN BEARING CAPS''' Some say (various sources internet) that one could use the 4 bolt mains of a V8 (aftermarket) and modify the block accordingly. But this would mean major machine work on the block surface, the caps and align bore and hone for new bearings. Not worth the hassle for a mere 250 - 300 hp build. So I'll have to go with the factory crank properly balanced (internal balance) which should easily withstand 300 hp. As the goal is below that number I should be fine with that. Found a crank from an older version of the engine. As the lenght's and the nose are the same we'll go and try this one. Belongs to a marine shop close by which had it available. I'll see with my machine shop once the internal parts are defined if we can internally balance it. That would help a lot as the bearings only need polishing. '''CYLINDER HEADS''' The 1994 V6 "Vortec" heads are '''NOT''' the same as the OEM LS31 heads for the 350ci V8's. They are "Vortec" heads but do not yet feature the heart shaped combustion chamber. Apart from the chamber design they already feature the "Vortec" ski-jump ramp. It would be cool if somebody with access to a flow bench could flow a pair of these heads. The 1.94 Intake and 1.50 Exhaust valves should have acceptable flow at low lifts and low rpm which would be a nice thing for a daily drive and low to mid rpm power band modifications. At the same time this will keep the cost way down. Modifications for screw in studs and decent roller rockers should deliver more power and a sturdy valvetrain. As of 2016-04-21 I got my order from Summit with the majority of parts for the build. I'll give a short brief on the parts and the reasons for ordering them. The part number in brackets () is the SUMMIT part number, all others are OEM numbers. '''CRANKSHAFT''' OEM - Got one from a guy close by who does marine engines. The crank is nearly brand new. As it may only need some polishing I'll go for this one. I consider this an option also for a build when simply buying a new crank OEM casting. It is a huge step up to a billet crank and I would consider that only if building an all out racing engine or a serious hot rod build. '''CONNECTING RODS''' EAGLE rods CRS570063D (ESP-570063D) which is an H-beam rod. C to C is 5.700" for standard pins. Careful when building the V6 - the big end bore is 2.225" not the V8's 2.125". As for my research this holds true for all the even fire engines in the 4.3l V6 series. The odd fire may have the 2.125" big end bores. Even at summit they list rods with the wrong big end bore for this application. (The solution is - measure - measure again - order) This seems to be the headache for all builders venturing into the 4.3l V6. It uses 5.700" lenght rods (center to center) but has larger diameter big ends than the small block V8. The V6 uses 2.25" crank pins instead of the common 2.125" on the V8. Crower has it's sportsman series rods for sale for this engine but indicates 2.125" BE bores. Sent them an e-mail to ask about the correct size. Would be a nice and fair priced rod. Else I have found an H-beam from EAGLE RODS with the correct dimensions which I have ordered as it takes too long to get responses. '''PISTONS''' 2016-03-30 Today ordered custom pistons at JE-Pistons - and had to cancel the order again. We found out that the stock pistons will not achieve the squish we are aiming at. But in order to order the correct pistons I have to test assemble the engine with the correct parts. This means machine the heads first. The pistons will be forged flat top with two valve relief pockets for the V6 (means a set of 6). We're running the risk as we had to get the compression distance (CD) right in order to achieve the target 10:1 compression ratio (CR). The stock pistons sit so low below deck that the standard 1.5" CD did not work out. Even the available shelf pistons with a CD of 1.565" is not even close enough to reach 9.7:1. At this time we're aiming at zero deck height with a 1 mm (0.04") gasket uncompressed so we get an ideal 0.85 mm (0.034") compressed gasket thickness. It will be interesting enough to see what the squish will do once we get it right. The OEM stuff is a joke and will not produce any pronounced squish. I have nearly a 1/4" distance to the heads flat portion from the dish and 1/8" at the edge of the dish. The new piston pins will be full floating at 0.925" diameter to fit on standard rod's small ends. We will use wire locks as the dual spirolocks would be overkill on a street engine which I will hopefully not rebuild a second time. I hope to use the Blazer to haul parts around and not fix it again. Because of the rather tame target rpm we're not going crazy with the rings. Just ordered them as file fit's to define gaps when building it because of the forged pistons. '''TIMING SET''' COMPCams 56-440-8 (CCA-3202) Standard near stock link belt with iron sprocket. The reason for this order is the balance shaft which I will retain. All other sets are not for the balance shaft engine and would most probably require a new timing gear cover. I'll leave that to a V8 build should the opportunity ever arise. '''CAMSHAFT''' COMPCams 260-AH (CCA-56-440-8) mildest grind will be used to be compatible with the stock TBI and computer and still be within emissions limitations. It is a 260/266 degree duration cam. Lobe separation 112 deg and durations of 206/210 deg at 0.050" lift. For the V6 with balance shaft. '''LIFTERS''' COMPCams 875-12 (CCA-875-12) hydraulic lifters are my choice because of their near stock dimensions and fitting with the stock plastic retainers. CompCams lifters should be a bit better than stock and prevent lifter pump up within the range of 6'000 rpm. Plus they should work with the camshaft and rocker arms. '''PUSHRODS''' Once the geometry has been defined (after machining the heads) and a test assembly has been made with the test rocker arm I have ordered we'll go an measure for custom pushrods. I'll be using COMPCams lifter measuring kit. '''ROCKER ARM STUD KIT and a bit of a warning''' ARP 100-7201 (ARP-100-7201) Set of screw in rocker studs. If correct they will feature a 3/8 by 24 thread for the rocker arm to be compatible with the adjustable nuts. WARNING - I have ordered studs with M10x1.5 mm threads for the screw in portion. This metric thread is common at my place and will make machining easier but may cause confusion in the US. One review actually stated that the buyer found out he had no tap for this thread. So make sure you get the correct one for your application. I also found out that these replacement studs may not work if you have 3/8" press in studs. An M10 tap will not fit into a 3/8" hole, there is not enough material left. Therefore you may need 7/16"-14 studs but they will be too high for the valve covers. Either cut the bosses or the studs. I'll go for the studs - see below in MACHINING THE HEADS. '''ROCKER ARMS''' COMPCams 1618-1 (CCA-1618-1) Ultra Pro Magnum Rocker Arm at 1.6:1 ratio. I have ordered just a single one to be able to check the valvetrain geometry for the machining of the studs and check rocker arm height with the OEM valves. At the same time I want to make sure they do not interfere with the OEM plastic covers. With the new camshaft I should already have about .100" more lift at the camshaft. I'll see during a test assembly if it fits (The result is - it does not fit and will need taller valve covers.). Inadvertently I have ordered a self aligning rocker arm which is just perfect for the application. It eliminates the need for guide plates and helps keep the stud height down. '''VALVE SPRINGS''' I'll employ beehive valve springs. The seat pressure and open pressure will be determined once the heads are finished and test assembled. We'll have to open up the valve pocket on the heads and at the same time machine the guide bosses on the upper portion of the head for more lift and new seals. '''VALVES''' Most probably I'll end up with stainless steel valves in OEM sizes. These will be determined again with the test assembled heads and engine with pistons as we have also to define clearances with the piston. === MACHINING AND PORTING === '''BLOCK''' Have to check if the block needs machining at all. The deck surfaces are nice. As we have a lot of compression gain to take advantage from I can equalize the decks to match the main crank bore. The cam bore is a bit of a question mark as we can measure that only after having the engine on the mill. If possible with oversize bearings I'll adjust that one as well. The block turned out to be quite nice. Decks are very straight may need machining just a couple hundredth's or so - talking in mm that means just a couple thousandth's in inches. Turned out that the deck height was 9.025" at my reference point at #1 cyl. The bores are the same. They just need honing 0.001" over which is about 0.02 mm. This with forged pistons at 4.000" will give just the right clearance and save me money. One question was if to use aftermarket billet main caps and drill the engine block for a 4 bolt cap pattern or save that money for the next build. The answer to this is "NO", not at this time. The next build may include this modification but aiming at some 250 hp does not require such measures. === MACHINE THE HEADS - PORTING === I will not port the heads as this would imply access to a flow-bench. What I did is blend all sharp edges in the combustion chamber even if it will cost me a bit of CR (compression ratio) to avoid hot spots in the chamber. Then the blending will extend into the runners behind the valve-seats. Also the valve guide bosses will be blended to a blunt round shape inside the runner. Avoiding sharp edges there will help keep the flow laminar. Then the bowl will be matched to the seats and finally I will have to touch them with the grinder to get smooth radii on the long and short side of the bend. This will be done before final cut on the seats. At the same time we'll see how to set the valves on the same altitude into the seats. Maybe the OEM valves will even do the job and just get a 3 angle job done. === MACHINE THE HEADS - VALVETRAIN === '''HEADS - MACHINE''' I have removed all the studs and prepared for screw in studs. I'll go with 3/8" studs. The choice of rockers will also be decisive. Aiming at a nice steel roller rocker such as CompCams Magnum Pro Roller Rocker 1,6:1. The geometry defined I'll have the bosses machined for proper height of the studs then the centers bored according to proper alignment from the lifter bores to the valve stems. The bosses will need cutting down by about 7/16 (8 mm) in total to put the rocker arm pivoting point into a correct geometry with some leeway up and down. Final measurement to be defined. '''CAUTION: ROCKER ARM STUDS''' The replacement studs proposed for this exact engine will not work! SUMMIT proposes ARP studs which are shorter than the V8 parts and feature a M10x1.5 thread for the base thread. This means the outer diameter of the screw in part is 10 mm. The original bosses on my heads have a diameter of 9.4 mm which leaves us with 0.6 mm diameter to cut the tap which is 0.3 mm on each thread. This is a mere 0.012"! The diameter of 9.4 mm is a perfect center bore for a 7/16"-14 thread. Last week (OCT 2016) I had the stud bosses machined by 1 mm (0.04") and 7/16-14 threads cut. Then we made a test assembly with some old TRW screw in studs and the new COMPCams 1.6 ratio rocker arm. What we found was that the valve geometry is too far to the exhaust side and I need to lower the pivot point of the rocker arm. We modified 1 of the studs (on a lathe cut a smaller radius onto the shoulder above the hex to lower the assy by some 3.5 mm total. This just put it about right and withouth the 3/8" rocker arm nut it just barely clears the valve covers. With this information we'll most probably cut the bosses down an additional 4 mm (0.16") for a total of 5 mm (0.20") to get enough clearance to adjust the valvetrain geometry on all valves. Maybe even 1 mm more. I will order a set of 16 studs from Summit and go with the ARP 134-7101 7/16"-14 base thread and 3/8"-24 adjuster thread with a protruding lenght of 1.750". With the bosses cut this will end up nearly exactly where the OEM studs stood. Machine the valve spring pockets and the valve guide bosses for clearance to accomodate the new lift and oil seals as well as the new springs. '''CAUTION: VALVE COVERS''' Even when having machined the bosses I'll end up about 5 mm (1/4") above the height the original rockers had. This is without the poly lock nuts which protrude an additional 5 - 8 mm. In order to clear the rocker arms I'm planning on machining a 20 - 25 mm (3/4 to 1") thick aluminium plate to act as a spacer. The next step is to check on the installation if it will fit under the hood and clear the air filter element. === PISTONS - ZERO DECK === It turns out to be the major problem of this build and to solve it I'll have to do a complete test-assembly including camshaft and rockers with valves. JE Pistons states that 1.585 CD (compression distance/height) pistons are a "zero deck" application. As my block is 9.025" deck height and I do not intend to machine .050" off that block. As I'm getting really close to the head now and using just the gasket to form the squish distance of some 0.030" - 0.040" (0.85 - 0.95 mm) in order to get good results, I will assemble it with the heads and valves and at the same time determine clearances. The pistons will need valve pockets to accommodate the greater valve lift. Next will be a test assembly to figure the correct dimensions for valves, beehive springs, retainers (maybe titanium - decided against as the beehive retainers are already smaller in diameter and lighter.), locks and finally the pushrods once I have the geometry defined. == 2017-03-21 TEST ASSEMBLY == It took quite a while to get it together for a test assembly. Mid of March 2017 it was the opportunity to put the block together with the crank I wish to use, one of the new EAGLE H-Beam rods and an OEM piston in order to come up with the compression distance (compression height) of the piston we want to use to get zero deck clearance. The final result is a CD of 1.575" to reach zero deck. The pockets need not be very deep. Despite the higher lift of around 0.555" with a 1.6:1 ratio rocker arm with this lame camshaft it looks as not being a big issue. We'll see what comes from it once I have the new pistons where we end up. ''' ASSEMBLY ''' The crankshaft is in good conditions and only needs polishing. I have used two old bearings in the first and last bearing as the forces of a test assembly of this kind of engine won't make any difference if all or just two mains are used. When assembling for final testing with the real valve springs I'll have all mains installed. All put together with a generous amount of engine oil. The piston and rod were easy. We had one piston pin polished by about 1/1000 and the OEM which are a press fit in the stock rods are a float in the new EAGLE rods. With no rings it was just cleaning out the bore add a bit of oil and slide the assembly in and center the rod on the crank pin. The quality of the rods is amazing. Make sure you have the correct orientation of the rods - they are offset. In order to assemble the block we put the first and last camshaft bearing (the old ones) back into place after having checked and deburred them. Make sure the new camshaft is not nicked or scratched by a bad bearing or when putting it into the block. Next was the new chain drive which installed easily. I found that when the camshaft marks are aligned and the engine is at TDC the valves are actually in overlap on the #1 piston and not on the compression stroke. Interesting that this is never explained in any literature I have. After having looked at several cam diagrams there seem to be both versions. For the CHEVI most use -360 deg to 0 and up to +360 deg on the charts. My raw data chart does simply look different but has the same data. The datapoints measured are exactly where the advertised cam chart said they should be. === CAMSHAFT DEGREEING === At the same time I had all the parts together I had the cam degreed. Turns out that the COMP CAMS grind is exactly on the advertised durations. The overlap is minimal, all in all a very mild cam which could work with the stock TBI without a new chip. Finally we'll see it on the dyno how it works out. The large COMPCAMS degree wheel was a perfect assistant. The only thing I have to change is insert two thin plastic washers between the nut and the wheel in order to tighten the nut without turning the wheel again. A small pointer was quickly fabricated with a 1/2" wide strip of stainless steel sheetmetal. Makes a nice pointer and I can put the heads on without touching the pointer. === PISTONS - FINALLY THERE - TEST ASSEMBLY WITH NEW STUFF === 2017-SEPT It took 3 months for our custom pistons to arrive but finally unpacked the JE forged pistons. Nice stuff, flat deck with 6 cc valve reliefs. We forgot to order the offset pin so they came centered. The slapping should not be audible and when warm it shouldn't really be an issue. At 4.004" diameter they fit the OEM 4.000" bore easily. Turns out they are just a couple 1/1000s below deck. When milling the deck to equalize and get the finish for the gasket they will sit at zero deck. The distance to the valves is also o.k. Pockets are nice and may just need some radiusing on the still rather sharp edge. Next thing will be the crankshaft. == 2017-12-01 CRANKSHAFT == Over the summer and autumn some steps got done: === CRANKSHAFT - PREPARATION === We have straigthened the cranksaft and in these mid September days I got a couple things done on it. Put it on the lathe and had all the oil holes chamfered. One side of these holes is normally paper thin and sharp. Just used a Dremel to radius them, then polished all the holes. Next step was to cut down on all the sharp edges on the counter-weights and throws. The removal will facilitate the work with the crank (no more cutting your hands) and the overall removal of 5 grams will not hurt balance. Then got a fine equalizing stone and checked that all the dents (the crank was handled carelessly before) not to protrude. Then using the lathe I polished all the bearing surfaces. The end of the crank needed a bit more polishing and a second pass with a 400 grit paper to get rid of the slight pitting where the one piece seal runs. I'll have to see that the new seal does not run in that area. The next step was to take the crank for nitriding which was done in a weeks time. After nitriding we straightened it again and i cleaned and washed it including polishing the bearing surfaces again. Nitriding leaves a powdery surface on the material. == BALANCING == It took the better part of the year to do other stuff and work on other projects like a 1963 Studebaker AVANTI. My friendly machine shop had me read the user manual on the balancing machine and showed me how it works. Then it took several evenings setting up the machine and get a first balancing run to figure out if we can modify the crankshaft from external to internal balance. === BOB WEIGHTS === Setting up 6 bob-weights at 0.05 g was just the beginning. The next step was an introduction to the balancing machine and I could balance all the bob-weights in order for them to spin round to 0.1g as well. This was done on a rotor shaft. === CRANK - 1st RUN === Then we sat up the balancing machine for the crankshaft, fixed the bob-weights and did a first spin to see what the imbalance was. Turns out there was a 170 g at the end of the crank and 70 g at the nose of the crank. Exactly where the factory had drilled the counterweights of the crankshaft. As the JE-Pistons are lighter we decided that it would be possible to balance the crankshaft as an "internally balanced" assembly. Taking all the weights off and the next steps would be to add material to where it had once be drilled away. === FILLING THE GAPS === Factory drills big holes into the counterweight, most probably for an economic manufacturing. Adding mass to the flexplate and the damper means, they can drill away on the counterweights. We wanted it to become internal balance so the first step was to make stell inserts to be welded into the counterweights. Chamfering the holes, and the inserting the 7/8" steel slugs into the holes was easy but time consuming. Welded into place and ground flat to match the counterweights. === CRANK - 2nd RUN === We needed a second run and I had to put all the bob-weights back on, spin it and determine the mass to be added. This time we were down to 70 g and 25 g. This would be achieved by two 7/8" slugs of about 1 1/4" length on the back and a single slug of 1/2" in the front. Determined the axis of the correction, then drilled the crank, reamed the holes, cleaned and washed the crankshaft and went on to turn the slugs of Tungsten to be inserted. === CRANK - 3rd RUN === Once the slugs were set we were in for a new run to adjust the mass and finally after some more turning and drilling we had the crank balanced internally to less than 0.5 g. For comparison: This balancing has been done by myself so I could spare the time and in addition learn about the balancing and how it is done. This would be in no case economical. If you had to pay for this service even in the US you would probably end up with a 1'000 $ bill for the balancing. 0.5 g dynamical balance is a race engine balancing job able to spin in excess of 8'000 rpm. === CRANK - FINISH === Once the slugs were solidly fixed in the crankshaft we could go on to work on the flexplate and the balancer. === CRANK - 4th and 5th RUN === The flexplate was relatively easy once the additional mass had been removed. We could now balance for a static balance but even the dynamic showed excellent results. Flexplate done it was time to remove it again and balance with the damper. This one had been advertised "factory balanced" but was off by several grams. Would have spun up to 6'000 rpm without causing too much problems the machine shop guy said but we brought the imbalance down to 0.7 g. The final run with all bob-weights, flexplate and damper showed less than 0.3 g residual imbalance. Crankshaft = done!

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