Cylinder head question

[cwilkie]

I checked the casting number on my heads and it's 6272292, which translate into 1971 402/454 Oval Open chamber heads on my 1969 396 engine.

Does this matter...the hp rating on the 396bb are 310hp and the rating on the 402/454 cylinder heads are 240/270? My Father says the motor should have a lot more snap and he thinks it's because of the heads. Anyway, I am looking for the correct 396 heads.

The intake casting number is 3883948 = 1966-68 396bb 325hp. Does it matter if I get open or closed chamber heads? Which are better? Please let me know.

Chance

[JimKshortstep4x4]

If you had the chamber size for both heads than you could tell for sure. I believe the 69 had smaller chambers and more power. You cannot compare the ratings between the 69 and 71 directly as the 69 was a gross figure and the 71 was a net figure.

I put open chamber heads on my 66 SS in place of the closed chamber so as to use regular gas. The power loss was substantial and with the open chambers the car is slugish!

Jim

[Purs]

I had a set of those heads on my 402 chevelle and it ran great. They come with big oval ports and have open chambers that should be around 115cc's. If my info is correct they were GM's early version of the 781's (which I'm currently running on my 496 )

It all depends on what pistons you have that will determine whether you want open or closed chambered heads. If you have flat top pistons you are probably around 9 to 1 compression (maybe less) with those heads. If you put a pair of closed chambered heads on there you might jump up to 10.5 to 1 (or more).

If you are looking for the '69 model year heads for your '69 396, some of the head casting numbers to look for end with 215 or 840, which are both closed chambered. I don't know any open chambered castings numbers for that year, but mortec.com will tell you.

Good luck.