Building Chevy 4.3 liter V6 - 1994 with balance shaft
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[[Category:Engine|B]] | [[Category:Engine|B]] | ||
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| + | == LAST EDIT == | ||
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| + | 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 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. | ||
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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. | 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 == | + | == 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. | 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''' | '''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. | + | 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''' | '''BLOCK''' | ||
| − | Nothing particular there. A couple of threaded holes are not used according to the | + | 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. |
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| + | '''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. | ||
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| + | '''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. | ||
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| + | '''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''' | '''OIL PAN''' | ||
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'''LIFTERS''' | '''LIFTERS''' | ||
| − | This has come to a surprise. It employs a plastic retainer along the full side of the lifter valley. One left, one right | + | 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. | I'll add more stuff as I go and discover what is particular or what differs largely from a standard pre 1988 small block. | ||
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'''CRANK AND CRANKCASE STUFF''' | '''CRANK AND CRANKCASE STUFF''' | ||
| − | The first thing to note is that the 1994 VIN Z engine has two | + | 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 == | == 2016-JAN-22 - TEARDOWN, THE REST == | ||
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'''WARNING!''' | '''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 | + | 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. | 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''' | '''CRANK REMOVAL''' | ||
| − | By removing the crank and the main bearing caps I can put the block back upside and it will rest on the | + | 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. |
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== 2016-FEB-12 - DISASSEMBLY, HEADS AND BLOCK, CLEANING == | == 2016-FEB-12 - DISASSEMBLY, HEADS AND BLOCK, CLEANING == | ||
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''' CAMSHAFT ''' | ''' CAMSHAFT ''' | ||
| − | The camshaft has | + | 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. |
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| + | Also make sure you understand the various lobes as they are in a specific order of intake and exhaust lobes. | ||
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| + | The bearings are pressed into the block and have an oil hole each which needs to be aligned properly with the blocks delivery holes. | ||
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| + | == 2016-OCT-27 - VALVETRAIN MODS == | ||
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| + | ''' 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. | ||
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| + | 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. | ||
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== TIPS AND TRICKS == | == 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 | + | 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 | + | 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. | 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. | 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 | + | 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. | + | 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. |
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| + | Put an engine together in a hurry and sloppily and it will leak and wear. | ||
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| + | Cleanliness is not an option but a MUST on the workplace. I do not assemble in the same location where I grind and sand. | ||
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| + | 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. | ||
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| + | 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 STAND == | ||
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== NEXT STEPS == | == 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. | |
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| + | 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. | ||
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| + | 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. | ||
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| + | 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''' | '''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). | ||
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Most suppliers would supply a billet crank for this engine from 3'000 to 5'000 $. | 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 | + | 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. |
| − | 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 balance it. That would help a lot as the bearings only need polishing. | + | '''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. | ||
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| + | 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''' | '''CYLINDER HEADS''' | ||
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It would be cool if somebody with access to a flow bench could flow a pair of these heads. | 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 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. | + | 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. | ||
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| + | '''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. | ||
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| + | '''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) | ||
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| + | 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. | ||
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| + | '''PISTONS''' | ||
| + | 2016-03-30 Today ordered custom pistons at JE-Pistons - and had to cancel the order again. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | '''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. | ||
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| + | '''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. | ||
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| + | '''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. | ||
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| + | '''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. | ||
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| + | '''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. | ||
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| + | 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. | ||
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| + | '''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. | ||
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| + | '''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. | ||
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| + | '''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 === | === MACHINING AND PORTING === | ||
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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. | 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''' | '''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. | + | 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. |
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| + | '''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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | '''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. | ||
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| + | === 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | ''' 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. | ||
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| + | 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. | ||
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| + | Make sure you have the correct orientation of the rods - they are offset. | ||
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| + | 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. | ||
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| + | Next was the new chain drive which installed easily. | ||
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| + | 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. | ||
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| + | === 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. | ||
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| + | 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. | ||
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| + | === 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | 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. | ||
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| + | == BALANCING == | ||
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| + | 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. | ||
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| + | === 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. | ||
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| + | 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. | ||
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| + | 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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