I posted this down in "Engines" too.

Looking for info on LS7 heads. Heading to a friends house to look at a pair of supposedly LS7 heads mounted on an LS6 motor. I looked thru my Colvins but couldn't find info on these heads. My understanding was that, although there is folklore saying that LS7 motors made it into production cars, these were only available OTC.

Questions:

1. Cylinder Head Casting #?
2. Correct date range for heads?
3. What are the external identifying ?features/marks i.e. casting flash line feature
4. Composition: Iron or Aluminum?

Any other pertinent info to ID these heads.

Thanks,
Sam

The heads are iron. After gas got bad GM put the open chamber LS-7 heads on the LS-6 crate engines they sold OTC to lower the compression. The heads are no big deal a modern head is much better a starting point.

A friend of mine has a LS7 crate motor and the heads are 990 casting. They are open chamber square ports. I don`t know if there are any other casting numbers for the LS7. I believe the 990 was also on the 71` LS6 which had 9to1 compression. Another friend of mine had a 71` LS6 in his camaro. With ported 990 heads on a 496 it ran 9.70`s. They are good heads but like Mike said, there are better, modern heads available.

Here is the info I gathered from the heads that I looked at last night:

* Casting # (both): 3994026
* Casting date (both): E 17 71
* "HI PERF" cast on both
* The Pass. side head had a hump cast in the casting flash line. The Drivers side head did not.

Colvin's Chev. by the Numbers reports that the application was for a 1971 Chevelle 454/425HP. Also there is not a note about a characteristic casting flash line feature (i found a hump on the drivers side head). I thot the only application for that cu.in. / HP combo was for the 1971 Corvette LS6?

Sam