I was starting to work on my engine and had quite a few questions about it i was hoping someone could help me out with. I was thinking about changing the heads on it so i was wondering how expensive it would be to do that. Also i was curious what the difference between a 1972 455 and a 1976 455 is. Are they both rockets? I heard that there was something different about their heads and i didn't know for sure.

 

They are both Rockets. 1968-72 heads are considered the best. I'm a small block (short deck, whatever, lol)guy, so I don't know much about the alphabet soup involved in the big blocks (tall deck's)

I just replaced the heads on my 350 due to cracks and a leaky head gasket. All tolled, including the purchase of new used heads, materials, and minor machine work, it was about $1,500.00.

I say don't replace unless you have to, 1972 is a fine starting point. If you have some reason to pull them, get em checked out at a reputable machine shop that has Olds experience, and go from there. If there is nothing wrong with them, let em be. But if you choose to replace em, there are many great people on here to buy new used heads from.

 

Thanks

 

still curious about the difference between the 1972 and 1976 455 heads

 

76 are probably j heads which 72 could be to. right by ur #1 sparkplug or #8 sparkplug there is a letter. D F H K Ka C G Ga E C A there might be more j heads are smog heads which alot of people stay away from. figure out what heads u have and we can help u from there.

 

our 76 engine is a J and our 72 engine is a G

 

The j heads u dont want they are the low compression smog heads the g heads are good heads and could be big valve heads. they are direct bolt ins on ur 76 455 u just need new gaskets. about 30 dollars for new head gasket, intake gasket and exhaust manifolds gasket.

 

So i can just switch them out? Do you have any good places to buy the gaskets from?

 

You can buy them from ur local auto parts store. or u can order them i like summit racing and competition products. if u have factory intake manifold u need a valley pan (i think i have never done a stock intake). if aftermarket intake then u need regular intake gaskets. i like fel-pro.

 

If you use the G heads off of a 72 455 a valve job and new guides should probably run you about 250-300 dollars plus your gasket set.

A set of earlier heads will need hardened exhaust seats added and that will add about 150 - 200 more to your bill.

Make sure your machine shop understands about the non adjustability of the olds valvetrain and can set the valves at the right height. They make tooling to check this.

 

A lot of info of the 455 and heads you can read in the "tech" part of this forum.

 

Every single Olds V8 built since 1949 has been called a "Rocket V8". It's a marketing term that has no performance implication, however the fact that you and many, many others still think it means something is a testament to the ability of the Olds marketing department.

 

I took both heads off and can't see any difference. What is the main difference or why are the G heads preferred?

 

u cant notice the differance. the g heads will breath alot better. u might have the small valve g heads which will still flow better than the j heads. the j head is a smog head. which will hold some power back.

 

Every single BBO head has a nominal 80cc chamber, except the D heads which were 72cc. Olds changed CR with the piston dish, not the heads.

Note, however, that I said "nominal". The as-cast chambers tend to run on the large side (roughly 83-84cc as-cast).

The primary difference between J and G heads is the port flow rates. J heads run fine on a daily driver. If ported they will run the same as any other iron BBO head. Most G heads got small valves also.