Editing Building Chevy 4.3 liter V6 - 1994 with balance shaft
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[[Category:Engine|B]] | [[Category:Engine|B]] | ||
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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 == |
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 | + | 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. 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. | 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 vehicles type and RPO's. It seems that this is an engine still based on the GEN I smallblock cast iron 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. |
'''CRANKSHAFT''' | '''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 | + | 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 bearing, oil pump attachment etc. are also the same as a 350 SBC. |
'''RODS''' | '''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 | + | 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. The piston pins are press fit (heated) and will be changed to full floating. |
'''PISTONS''' | '''PISTONS''' | ||
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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 which two bolts each fixed 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 I guess are for oil 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 bold 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 lower the rods and pistons 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. | ||
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'''CRANK REMOVAL''' | '''CRANK REMOVAL''' | ||
− | By removing the crank and the main bearing caps I can put the block back upside | + | By removing the crank and the main bearing caps I can put the block back back upside and it will rest on the base nicely for transport. 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 as the bearing is supposed to. 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 == | == 2016-FEB-12 - DISASSEMBLY, HEADS AND BLOCK, CLEANING == | ||
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''' CAMSHAFT ''' | ''' CAMSHAFT ''' | ||
− | The camshaft has | + | The camshaft has terrible oddities. I'm a metric guy and have measured 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). I hope that CompCams or Crane deliver the precision they advertise. (BTW measured not only where the roller of the lifter runs but also at the edges of the cam. |
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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. |
− | 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 and best is to go 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. | ||
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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. | 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. | 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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+ | I'm in restoration of old and historic cars. We do 12 cylinder Ferraris at the place I work and it all comes down to the finish. | ||
Put an engine together in a hurry and sloppily and it will leak and wear. | Put an engine together in a hurry and sloppily and it will leak and wear. | ||
− | Cleanliness is not an option but a | + | 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 by sanding the intake. The little bit of remaining grit which got not washed out properly had it killed 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. | |
== ENGINE STAND == | == ENGINE STAND == | ||
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'''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. | + | 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. |
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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 put out 500 at max. |
'''MAIN BEARING CAPS''' | '''MAIN BEARING CAPS''' | ||
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'''PISTONS''' | '''PISTONS''' | ||
− | 2016-03-30 Today ordered custom pistons at JE-Pistons - | + | 2016-03-30 Today ordered custom pistons at JE-Pistons. Actually ordered them only on the 2016-06-20 as my machine shop forgot about them... They 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"). 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. |
− | + | 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. | |
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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 | + | |
'''TIMING SET''' | '''TIMING SET''' | ||
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'''ROCKER ARM STUD KIT and a bit of a warning''' | '''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. | 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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'''ROCKER ARMS''' | '''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 | + | 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 lifter I have been sent is a self adjusting featuring two lips left and right of the roller tip thus most probably eliminating the need for guide plates. |
'''VALVE SPRINGS''' | '''VALVE SPRINGS''' | ||
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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. | ||
− | + | The big question now is if to use aftermarket billet main caps and drill the engine block now 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 === | === MACHINE THE HEADS - PORTING === | ||
− | I will not port the heads as this would imply access to a flow-bench. What I | + | I will not port the heads as this would imply access to a flow-bench. What I will do 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. | + | 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. |
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'''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. Most probably I will NOT need guide plates as the rocker arms have stem guides. |
− | '''CAUTION: | + | '''CAUTION:''' |
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 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. | 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 | + | 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 a 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 | + | What we found was that the valve geometry is too far to the exhaust side and I need to lower the axle 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 | + | 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 a 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. | 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 | + | Machine the valve spring pockets and the valve guide bosses for clearance to accomodate the new lift and oil seals. |
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=== PISTONS - ZERO DECK === | === PISTONS - ZERO DECK === | ||
− | It turns out to be | + | It turns out to be a problem and to solve this I will 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 while this is not entirely true. As my block is 9.025" deck height and I do not intend to machine .050" off that block I will have to go with custom pistons at a 1.600" CD. 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), locks and finally the pushrods once I have the geometry defined. | |
− | + | Let's continue the build. |