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So, my car is has an R code which apparently means it's an Oldsmobile 4-bbl engine, which I believe means it's one of the rocket engines.

If this is true the the pre '77 engines had better flowing heads, I believe 9:1 compression as opposed to 8.4:1.

Would it be possible to fit the heads from an older car without having to change the cam?? I'm also looking at fitting performance I let manifold, Holley carb and better headers/exhaust.

Typically you won't need to change the cam when you swap between OE heads, if the engine is stock. If any work has been done to it, you'd have to figure out what was done and go from there. I couldn't find any specific '77+ swaps to older heads (also, good luck finding them), but worst case is you'd have to also change the pushrod length if the heads are really different. When I put the older high compression heads on my BBB 455, they were 100% bolt in, no other parts needed.

Brilliant, thanks for the help. I've been advised skimming he head my change the compression to pre '77 levels, would this be a better option? I've been advised many different things and don't know what to believe! Haha.

I believe there is also a thinner head gasket available. Basically, anything that improves compression will improve power. Same goes for flow. If your heads have enough meat, you can have larger valves put in, and a basic port and casting cleanup. You would get more out of a bump in compression. Also stock cast iron exhaust manifolds are not known for their ability to flow well.

If you have the heads milled, you will have to get shorter pushrods. This is something that if you want to do, you're best information is going to come from the local machine shop. There are also valve to piston clearances that need to be kept track of - which may limit how far they can be milled.

Usually, if you want to improve flow, you'd want to have a cam, valves, and headers done to get the most from it.

JimmyF wrote:So, my car is has an R code which apparently means it's an Oldsmobile 4-bbl engine, which I believe means it's one of the rocket engines.

If this is true the the pre '77 engines had better flowing heads, I believe 9:1 compression as opposed to 8.4:1.

Would it be possible to fit the heads from an older car without having to change the cam?? I'm also looking at fitting performance I let manifold, Holley carb and better headers/exhaust.

Many people believe that an Oldsmobile has two engine varieties of the 350,a standard 350 and a rocket 350.I've owned a 74,69,75,72,oldsmobiles.the myth that there's a special "rocket" version of the old's lineup is just that,a myth.prior to 1975,all old's v-8s were referred to as the rocket .some even say the color of the engine determines if it's a rocket or "regular" old's engine.Also a myth.The last year that Oldsmobile used the rocket label for any of their v-8s was 1974.After that,starting in 1975,once catyletic converters were being used the label on the air cleaner said econo 350.So there was no special rocket engine,technically any old's v-8 can be referred to as a rocket engine.But like I said the last year that an old's engine was designated as a rocket on the air cleaner was 74,and every old's v-8 was a rocket.Not trying to be a downer lol but just thought I'd put my two cents in as I've had many Oldsmobiles.and my dad sold them for 30 years.But as far as there being a special letter in the vin designating a rocket engine is just not so.

JimmyF wrote:So, my car is has an R code which apparently means it's an Oldsmobile 4-bbl engine, which I believe means it's one of the rocket engines.

If this is true the the pre '77 engines had better flowing heads, I believe 9:1 compression as opposed to 8.4:1.

Would it be possible to fit the heads from an older car without having to change the cam?? I'm also looking at fitting performance I let manifold, Holley carb and better headers/exhaust.

Pre 75 heads are the better flowing heads,but preferably pre 72 for the best flowing heads on an old's,even in 71 old's took quite a commpression hit,so your best bet would be a 70 or older.

On an Olds, the easiest way to truly tell which head you have is to look for the 1" tall number beside the #1 cyl. (Small block olds heads are identified by number, Big-Block Olds by letter, 1972 head also had a small subscript letter to differentiate them from their 1971 versions, the subscript "A" meaning they have hardened seats for use with the "NEW" unleaded fuels) Note: yes, this info also appears in the same spot by the #8 spark plug (heads are symmetrical), but the air-box usually obscures it.

A 1977 Olds 350 should have "3A" head (the 403ci had "4A" heads, 1977-1979. Both the number and letter are the same height.

>>> 1977 3A heads are HORRIBLE. They were lightened (thinned) from the factory, and when you combine the REALLY small valve size with the fact there is not a lot of thickness allowing you to port them to improve the passages, there is very little positive to be said of them....unless you need a really heavy paperweight.

"8" code heads were used from 1973-1976 and decent in that they have better valve size and enough meat in them to allow for porting inprovements.

ANYTHING 1968-1972 should work well with few modifications, and VERY well with porting.

Stay away from the early 330cio heads as some of those blocks had 45° lifter banks (as opposed to the later and much more common 39°) meaning that the pushrod holes through the heads would be at the wrong angle....they can be fixed with machine work, but much easier to just get heads that will fit without modification.

Another thing to keep in mind, the '77+ heads and blocks used 1/2" head bolts. '76 and back used 7/16", so ANY early head you get will need to have the head-bolt holes drilled out.

With regard to the cam...the 1977 cam is an absolute joke from just about ANY standpoint (they were only around .400" lift Int/Exh).

You will pick up some performance just changing the heads (as the factory head IS a major restriction), but the biggest improvement is the combination of cam, heads, and exhaust.