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Old 01-01-2012, 12:09 PM
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double post. please remove.

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Old 01-01-2012, 12:11 PM
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ssmonty is right on the money with his reply. If you don't match up the SCR with the cam's intake closing point, you have no idea if you have overbuilt or you're leaving some on the table. That's what figuring the DCR is all about, but you have to know the SCR first.
You fellows who don't follow through with the math on your builds are shooting yourselves in the foot.
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Old 01-01-2012, 11:14 PM
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the rods were 5.702.. i think it was hard to measure without removing the pistons. i do not know how to measure the piston cc or how to check what the compression ratio is..... things got tough i measured the cam that was in the truck and it had .454 lift intake and exhaust.... i put the motor back together for now and will worry about the camshaft later all i pretty much did was cleaned her up threw some 64cc vortechs bought a new intake and got a holley750 dp for the top i need my truck back so i had no choice but to get it done... the cam can be changed at anytime i really appreciate all of your replys.... is there a way to check compression ratio with the motor in the truck???
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Old 01-02-2012, 07:51 AM
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read this 406 build(s)

http://www.chevyhiperformance.com/te...d/viewall.html
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Old 01-02-2012, 09:44 AM
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After its warmed up, you can remove the plugs, the coil wire, prop the throttle wide open, screw in a compression gauge into the spark plug holes, and record your readings. 180 psi (dynamic pressure)is about as high as I would want to see on an engine with iron heads, tight quench(0.040" or less), cold air intake, 180* thermostat, good cooling system, excellent ignition system, running pump gas, in perfect tune, in a mild climate at sea level. I'm sure others will have a different opinion, but thats my 2 cents. I've read David Vizzard recommend 200psi if I'm not mistaken. Increased ambient temperature, severe duty/heavy loads, and low octane fuel would be reasons to lower the dynamic compression. Fast burn heads, polished chambers, and aluminum heads could be reasons to raise it.
If you install a smaller duration cam the psi will increase. If you advance the cam you have the pressure will increase. I can't say how much per degree of duration. Most cams already have advance ground into them when installed straight up. Hopefully someone else with more experience than me will chime in. Hope this gives you an idea anyway.
Good Luck!
ssmonty
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