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The stock compression ratio will have been measured at around 7.4:1, no matter what the books say. The key thing here is he's using stock heads. If using a closed chamber head your pistons will vary.

I worked with a friend several years ago to build his '76 W250's 440. On my suggestion he went to KB 184 pistons which have a "quench dome" that requires machining to fit. That way the machinist can make sure the squish distance is about 0.040". With some careful measuring and machining, including IIRC milling some off the non-dome top side of the pistons, he ended up with 0.040" squish and 9.5:1 measured compression.

The camshaft was a Hughes with 216 degrees intake and I believe 224 exhaust on a 112 LSA. Intake and carb were stock. He used Hedman Elite headers. Distributor was either stock or MP electronic HP, I don't remember.

I was secretly a little worried about that compression in an iron-headed motor with a rather short intake lobe. I was really relieved when he reported the engine ran like a bear and didn't ping on midgrade (87 octane @ 5900 ft elevation) while doubling the previous gas mileage.

He thanked me later for the tech support and said it had exceeded his wildest expectations and the extra $$ he'd had to put into machining was well worth it. The rebuild turned the truck into something he could afford to drive regularly.

Nothing beats squish and compression for getting results!

R.

PS: If at all possible, a set of long-tube headers will fatten up the torque curve below the torque peak and help drivability, power and economy.

PPS: No need to spend more $ on a larger carb, that 750 is good for 450 hp at least, and that's your top until he gets more flow out of the heads. For a 2-plane intake the only decent choice is the Edelbrock Performer RPM. Everything else is in second place.



Thanks for the info, helps alot!