Building Chevy 4.3 liter V6 - 1994 with balance shaft
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''' CAMSHAFT ''' | ''' CAMSHAFT ''' | ||
| − | 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). | + | 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. |
== TIPS AND TRICKS == | == TIPS AND TRICKS == | ||
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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 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. | ||
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| + | === MACHINING AND PORTING === | ||
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| + | '''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. | ||
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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. | ||
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'''PORTING''' | '''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 stems will be blended to a blunt round shape inside the runner. Avoiding sharp edges there will help keep the flow. | 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 stems will be blended to a blunt round shape inside the runner. Avoiding sharp edges there will help keep the flow. | ||
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