BBC #820 heads

[relic7680]

A buddy of mine has an old set of oval port BBC heads collecting dust in his shop. He said that they were 'garbage smog heads' and not worth anything. I decided to do some research. They are both #3993820 castings dated July 1 1970 and July 3 1970. From what I can tell on the internet, this casting # was used for the following:

1971 402 300/330HP and 1971 454 365HP LS-5

I was considering offering him 50 bucks for them, seeing as how they are 'worthless'. Can anyone shed some more light on the performance characteristics of these heads? Are they worth investing in?

[MrPbody]

The chamber shape is "suspect". There's a "flat" behind the exhaust valve, not present in the earlier "open chamber" heads.

That being said, we've built several 396s and 402s with that head, with good results. They will help keep compression under 9.5:1, the "line" for 93 octane. We enlarge the valves to the "high performance" head sizes (2.190/1.88). This really "wakes them up" over 4,000 RPM.

When combined with a good cam for a low-compression engine along with some judicious port work, these heads can make good power up to about 6,500 RPM with the smaller-cubed BBCs. I wouldn't recommend them for any high-powered applications over 410 CID.

Jim

[relic7680]

Thanks for the info......anyway, my buddy won't sell them for any small amount of money so I guess they will sit forever.