bherman
Well-Known Member
Hi guys', a friend that helps me a bunch with my projects purchased a 70 Challenger that was raced as a super stocker and he would like to street it, maintaining the SS look. He would like to use the engine that came with the car while he's working on updating the rest of the vehicle. His plan is to build a new engine for the car when it's all sorted out.
The engine is a 1975 block, STD bore (4.320)and stroke (3.75) 440. The cylinder heads are 915 castings that have been reworked with 2.1875 intakes and 1.875 exhaust valves, we cc'd the chambers and got 76 cc's. The pistons are TRW L2295's which TRW claims is a 12 cc dome. The pistons have been machined for valve clearance with the larger valves and when we cc'd them we got an 8cc dome. The quench surface is .030 below deck and the head gasket was .022 thick. After performing the math and using two different online calculators we came up with approximately 12.2 comp ratio. We were hoping to get the CR down to pump gas territory.
My friend does not want to change the pistons and re-balance the assembly.
The options that we are considering and the CR'S we think that option produces;
Leave everything as is and use an .080 thick Cometic head gasket. (CR 10.49) I've read that the Cometic gaskets require a better than average surface finish, I have a concern about sealing.
Change to 906/452 heads, I'm told these are 88 cc's and use .022 steel shim gasket (CR10.3).
Change to an 84 CC Edelbrock head and Felpro 1009 head gasket (.039 thick) (CR 10.7).
Change to an 84 cc Edelbrock head and Edlebrock white gasket (.051 thick) (CR 10.45).
I don't believe that we would wish to use the 906/452 heads without reworking them for larger valves, at that point the cost for the iron heads is close to what we can purchase the edelbrocks' for. Your opinion would be greatly appreciated, thanks Brian.
The engine is a 1975 block, STD bore (4.320)and stroke (3.75) 440. The cylinder heads are 915 castings that have been reworked with 2.1875 intakes and 1.875 exhaust valves, we cc'd the chambers and got 76 cc's. The pistons are TRW L2295's which TRW claims is a 12 cc dome. The pistons have been machined for valve clearance with the larger valves and when we cc'd them we got an 8cc dome. The quench surface is .030 below deck and the head gasket was .022 thick. After performing the math and using two different online calculators we came up with approximately 12.2 comp ratio. We were hoping to get the CR down to pump gas territory.
My friend does not want to change the pistons and re-balance the assembly.
The options that we are considering and the CR'S we think that option produces;
Leave everything as is and use an .080 thick Cometic head gasket. (CR 10.49) I've read that the Cometic gaskets require a better than average surface finish, I have a concern about sealing.
Change to 906/452 heads, I'm told these are 88 cc's and use .022 steel shim gasket (CR10.3).
Change to an 84 CC Edelbrock head and Felpro 1009 head gasket (.039 thick) (CR 10.7).
Change to an 84 cc Edelbrock head and Edlebrock white gasket (.051 thick) (CR 10.45).
I don't believe that we would wish to use the 906/452 heads without reworking them for larger valves, at that point the cost for the iron heads is close to what we can purchase the edelbrocks' for. Your opinion would be greatly appreciated, thanks Brian.
