Thanks for the great info, I'm going to look for a set just to have on hand. Are those still the older style four bolt valve covers? What do they mean by the "7 bolt ex"? Exhaust manifold bolt pattern?
Yes, they are still the old 4 bolt type, edge clamp valve covers. They have the accessory mounting holes in the ends, and the 7 bolt exhaust is an extra bolt hole in the outer ( on the far left if you're facing the exhaust exits) exhaust flange. I really don't know why they added the extra exhaust bolt hole. The only drawback to these heads is that they are thin. We're working on a set of 041 heads and I'll bet there is a good 4lbs difference per head. The amount of grinding they'll stand is probably minimal, but won't require much if keeping the 1.85" intake valve and used on a smaller displacement engine with a cam profile in the range I listed earlier. The advantage would be a much better compression with little if any dome and an improved combustion chamber shape over the old Power Pack heads. Overall you'd get much better combustion characteristics with these heads over the other choices. The drawback, they are just not period correct pieces. Its one of those things where you ask yourself what you realisticly want and go from there. Hud
I've been sitting on a set of 462 heads for about 12 years now, that have the angle plug conversion, excessive milling and port work done, as well as having been machined for bigger valve springs. They've been used on a 400 at some point, because they have steam holes drilled. On the intake side the name "Pearson" has been stamped on them, and on each end of the outside row of headbolts is stamped "Rat". My guess is they've been on a circle track engine. They would probably be overkill on my 283 at this point, wouldn't they?
Hi Tomcat,, GM head # 370,, is a camel hump head with holes... 69---70..thats what i use on 350...Good Luck 52 csb
hi guys having built several engines carfully with differant heads i can say use 305 2 barrel heads. But if you want more power then a 327 is better then a 283 or a 305 i dont recomend big valves for anything smaller then 327 use a single 4 barell you cant go wrong with the old rochester 283 carb there are still a few on ebay wcfbs give great millage but mild power someone said a 3/4 vet cam whatever that was . I am going to suggest sealing of cylinders is a lot of the power differance between one engine and another and cheveys in general can be verry average" if you ever get one that seals excelent though ( unuseual) having been run in through some unknown random chance ( most likely good driving and good oil) you will know it. One way to know a perfect block is it will have a crome like scheen to the cylinder surface not as bright but smooth like a chainsaw engine with a real good chrome bore (older saw). I have such an engine packed in grease its been sitting for 15 years its a 307 there pistons are nor as good as a 283s so if i ever do build it its not going to see hard service. A motor with Superior sealing sounds a lot different then an average one . of course perfect circle has the best rings.also KEEP those valve seat widths down to 1/16 intakes and less then 1/8" exhaust thanks for listening to my 2cents wurth ps there are exceptions to the rules its possible that mild rust itself my produce a certain lubrication improvement(cylinder retention) effect but not when located near the top 1 inch of the bore i dont mean low pits i mean microscopic
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