Building Chevy 4.3 liter V6 - 1994 with balance shaft
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'''CONNECTING RODS''' | '''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) | 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. | ||
'''PISTONS''' | '''PISTONS''' | ||
| − | + | 2016-03-30 Today ordered custom pistons at JE-Pistons. 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 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 squish. I have nearly a 1/4" distance to the heads flat portion. | |
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| + | The 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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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. | 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. | ||
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'''HEADS - PORTING''' | '''HEADS - PORTING''' | ||
| − | 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 | + | 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. |
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| + | 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. | ||
'''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. Came up some new information about valvetrain geometry which will be incorporated here. | + | 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. Came up some new information about valvetrain geometry which will be incorporated here. Most probably I will need guide plates as well. |
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| + | Machine the valve spring pockets and the valve guide bosses for clearance to accomodate the new lift and oil seals. | ||
| − | Next will be the | + | 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. | Let's continue the build. | ||
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