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Old 11-26-2011, 12:15 PM
wild_man84 wild_man84 is offline
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I have stock Gen IV 454 & 781 Heads, Compression ????

Im going to be working with stock 4 bolt main 454 Gen IV bottom end.. ( in vehicle) I have a set of stock 781 heads.... I'm ready to send the heads off to a machine shop for work ( if needed/recommended) for new parts to match cam and for port&polish job.

Ive been searching and it looks like the cc's of the 781 are 115-118 cc's. not sure on the valves.

The cam im looking at recommends CR to be 9:1+.
Can I and how do I get my CR up without bottom end work?

Should I get the bigger valves 2.19 and 1.88?
What should I tell the machine shop to do with my heads ( mill? cc? P&P )
Should I use 0.020" shims (read that) Port match gasket?
The the cam recommends 2 different valve spring sizes, how Would I determine the answer. so in the future, I can figure it out for myself instead of having to ask. here is what it offers/recommends for the cam

Single Outer Valve Springs: 1.524" O.D., 1.110" I.D. OR
Dual Valve Springs: 1.509" O.D. Outer, .697" I.D. Inner On a guess, Id say the Dual valve springs BC of High RPM and my cam is .51 lift int & exh. and my rocker ratio is 1.72? is that right


Not a daily driver.. Looking to get high tq. rpm range (2200 to 5800)

Any input/advice/direction would be appreciated.... thanks in advance

Last edited by wild_man84; 11-26-2011 at 12:38 PM. Reason: forgot valve spring size question
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