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Old 11-21-2012, 08:29 PM
mouse77 mouse77 is offline
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Originally Posted by cobalt327 View Post
If the stock pistons are going to be reused, AND if the dish is 24cc like the 400 often used stock, the 64cc chamber size will put the compression ratio (CR) at about 9.6:1 using a 0.040" quench.
Your gonna confuse the poor kid with this talk of the quench myth.
You cant calculate "quench" effectively when you are using a full dish piston, the "quench" is essentially the entire combustion chamber with those pistons.
Perhaps the raised ring on the piston, (Probably almost .030 in the hole with an unmachined deck) Might be closer to .070 "quench" (.030 in the hole, stock style .038 gasket), but still will be very low compression.
The 330/350 horse GM crates with a very similar piston, and vortec heads are 9.0 to 1.

I agree that the vortec is probably the way to go in your boat. BUT, i would advise you have a machine shop drill the steam holes (If the vortecs even have a water passage there) I know the lower coolant area in the vortec has a very large opening, and i would be concered about drilling a hole that close to it.

If it runs/ran well, and the valve job doesnt show any cracks around the exhaust seat, you are pretty much good to go. The 400 were bad because of the siamese bore (airlock), and people not bleeding them right. The heads were not weak, per se. They were the same casting minus the steam holes as most other HD chev engines of the time. Lots and lots of people never cracked a head on them.

Roller rockers are a benefit, yes. At your stage, there are probably better things to spend your money on. Roller timing chain for durabilty, rebuilt/new/better distributor, machined valve locks, machine for positive seals on the valves, decking the block etc

Go to whoever in your area has the best reputation, and talk to them, and tell them your budget. They will work with you to get you what you need.
Oh, and you are for sure going to have to put valves and guides in them. They were sloppy in 1976 when they were brand new.

Good luck!
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