Could you please tell me these SBC heads are here are the numbers-- 3795896 -- Thanks I was told they are Power Pak heads ? ?
Had a set on a 283 and later on a 307, opened the intake from 1.75 to 1.94" int. valves, blended the bowl under valve, cleaned up exh. bowl under valve, pinned the studs ( 40 years ago) matched ports to intake, both engines ran the same Duntov 12/18 cam, header's, but really, iron manifolds would be fine , the cam was snappy with good comp. ( 10.5+). About .430" lift? Good in a light car, 327 c.i. max. manual trans. No flow after 5500 rpm or so. Mag for cracks, they're ancient, cut for pc stem seals, miss those days, oh well.
As others said, power pack heads, They do work great on a 307. Had a pair on a 307 with a 300 hp 327 intake and a 650 Holley spread bore that ran like a bandit.
By the way, if the exhaust seats are junk, you may have to spring for seat inserts for today's fuel, Don't just sink the valves (grind too much) the dollars to save them may start to get crazy, so common sense may tell your wallet to buy a set of iron vortecs.
Do they have the little triangle on the end? That's how you tell a Power Pack head. If you want to know how old it is, look for the casting date code, which is also under the valve cover, like the casting number.
Dont fix old stuff. It’s cheaper to buy new stuff. Base 327 heads. I’d run em. Have yet to sink a valve and I put lots of miles on regular seats. However, I had hardened seats put in some 461s due to it going in a heavy ride. Didn’t cost much and no ugly accessory holes. And it didn’t cost more to rework these old heads than buying new ones Wonder if valves sink as often as Vortek heads crack?
I did a lot of research on chevy heads a couple years ago, looking to get the best for my money and I found the Vortec heads were the best flowing heads chevy ever made and you can buy an intake manifold to adapt to the old style chevy engines. IMHO.
Unfortunately, you can't trust most of the lists that you find on the internet. This casting number wasn't used until 1962, and not after 1967. Also, the chambers are close to 64cc. Lots of guys have freaked out when they see that, according to the listing they found, they've got a pair of 1957 283/283 HP F I. heads. Technically, they do...but they're the same heads that were used on all of the 220 HP 4 bbl. engines as well, and aren't worth megabucks. The 997 heads that were used on the 270 HP engines are another story.
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