I need 915 head advice
- Thread starter LR1970
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What pistons and what is your bore size?
I have a std bore 440 with the factory .050 down pistons (1970 passenger car motor), closed chamber 516's, steel shim gaskets and calculated it to be 10.3-1. Maybe one of these days I'll get installed in something.
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SRP 213455
Double checked my check....lol wouldn't think the valve reliefs would make much difference. No reliefs in mine. Just .030 more down than those.
LSS&B
Well-Known Member
Thanks for the info, 1968rt
So you are using these pistons 213455 at 10.2:1 compression?
https://www.jepistons.com/product/s...piston-kit-4-350-in-bore-2-062-in-ch-6-00-cc/
What cylinder pressure readings are you getting with the 10.2:1 and Mopar .528 cam?
Thanks again.
I have an old DC Hemi grind cam in it...
1968rt
Well-Known Member
Actually I have not checked cylinder pressure, motor is not broken in yet. I assume you have the .484-284? Decent street cam but not a great cam for manifolds. Youll need headers and a convertor to make it work good and not great with power brakes.
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1968rt
Well-Known Member
Here are the figures I came up with: JE calculator seems high, used Compression Ratio Calculato
--------------------------------------------------------------------72cc 80cc 84cc -----------------------------------------
445 | 4.350 | 3.750 | 6.768 | 10.705 | 2.062 | 11.4 | 10.5 | 10.1 | -6cc | 690 | H | 0.030 |
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LSS&B
Well-Known Member
P4120653AE Dur @ .050 is 241 and the LSA is 112, lift is .528, solid lifter, operating range 2800-7500rpm.
I guess your car is serious street/strip.
That's about 1100rpms of optimism built in there
LSS&B
Well-Known Member
So that's HP, operation at high end of cam rpm.
How is torque, operation at 1000-2500 rpm? Thanks again!
1968rt
Well-Known Member
If you need torque at those rpms maybe you need a cummins?
LSS&B
Well-Known Member
I am planning 440 build using forged steel crank, stock connecting rods, and 915 heads that I already own.
I researched a Mopar 528 cam and came up with the specs I posted, including 2800-7500 rpm range, from Summit's website.
Sometimes, cam with a beginning rpm curve as high as 2800 rpm is hard to run on the street. But maybe solid lifter changes that.
I was looking for how the engine performs at lower rpm, which I defined as 1000-2500rpm.
If I am wrong or inaccurate on some technicality in defining low end power as torque, thanks anyway.
I researched a Mopar 528 cam and came up with the specs I posted, including 2800-7500 rpm range, from Summit's website.
Sometimes, cam with a beginning rpm curve as high as 2800 rpm is hard to run on the street. But maybe solid lifter changes that.
I was looking for how the engine performs at lower rpm, which I defined as 1000-2500rpm.
If I am wrong or inaccurate on some technicality in defining low end power as torque, thanks anyway.
The .528 is a great street cam even in a low compression 440, I imagine yours might be good. Summit is incorrect on the rpm range. It's a smaller cam than a hyd 292 509. I'm wondering if it's a 4 spd?
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