Max compression for pump gas iron head

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You folks are great. The input and debate is always productive.
 
As far as stock pistons go, the 67-69 318 pistons are closest to the deck (.036) 70-71 @ .060, 72-86 @ 056. The earlier pistons work fine in the later blocks. They also are cut with 4 valve relief pockets.

Compression ratio on the 67-69 engines was 9.2:1 from there on it goes down to 8.5:1 until the 302 heads were released in 85 which bumped it back up to 9.1:1.

Personally, I'm running the 302 heads on a '68 engine equipped with a .441 lift cam, duration 218/228 @ .050 lift. No problems on 89 octane.
 
Qwk Dust:
If you go to "Wallace racing/engine calculators" you will find calculators that will help you not only figure Static Comp, but Dynamic Comp and cranking pressure. you can then enter different cam specs and see how it effects those figures. I am trying to sort out the same issues but for AL heads.
There are a few other posts in the forums on octane/comp ratios as well.
Andrew
 
qwk dust said:
What is the maximum compression ratio that can be run with good 93 octane pump gas in an iron headed motor. I am building a 318 with 302 casting heads and want to get the highest compression ratio possible without getting too close to the ragged edge of detonation on good pump gas. The machine shop will be decking the block to get my ratio just where I want it with the 59cc heads so I could really use your advise. thx
Click to expand...
with very careful planning.. 12:1 shouldnt be a problem. head/main studs are a must, along with expensive custom forged pistons.
soooooo a better way to ask the question would be "how much do i have to spend to get the highest cr possible
with 93 octane?"
 
OK, lets see, 12-1 iron headed engine running pump gas. I don't think so. Not without a wild cam and retarded timing specs. Might as well inject alchol, hic, all-coe hole,,all co-in a hoe, Hic all hoes in a co-co-coat, 151! Naaa, WHITE LIGHTENINENING!!! choloco loco loco howle.....coated hoes.....hic... (Falls down) THUD!
 
yah you got me... more like 11.97:1 ;)
k, anyways, yah, choloco loco loco howle is always the best fuel to use,
absolute is a absolute second, condoms in the glove box and a hoe-to-go would be a close third LOL!
cheers
 
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