Al2011

Will 7a (small a) SBO heads fit 1976 or earlier 455 BBO. Any mods needed. I'm only asking because I found a shortblock but I only have my 350 7a heads available at the time. Also there is a rebuilder here locally that sells 455 rebuilt with heads for $1800. You think a motor for that price will make a good street weekend performance motor or should I just rebuild my 350 with performance parts?

gearheads78

No but there are a set of C heads on here for sale.

https://classicoldsmobile.com/forums...eads-pics.html

72442clone

My '72 455 has #5 small block heads on it which have larger valves installed, and runs outstanding producing all sorts of power and good compression. These heads were on it when I bought the car, and haven't changed them yet. I'll be getting some Edelbrock perfomer series heads as soon as I can afford it.

MDchanic

I believe that the SB heads will physically bolt on, but you will have to contend with smaller valves, smaller ports, and using the smaller SB exhaust manifolds. You'll wind up with a sort of a Frankenmotor that nobody will be really sure how to tune right.

Probably not worth it.

- Eric

gearheads78

Yes they will bolt on but you have small chambers and mega shrouded valves.

joe_padavano

Again, bumping compression at the expense of valve and port size is usually NOT a good trade. Yeah, it will run, but it won't be all it can be.

oldsy

What amount of hp do you get?Is the rest of the motor stock?I have 70' 350 heads and a 71' 455 so im looking to see if that would make a good combo.thanks.

72442clone

I have about 550 hp at the flywheel. The rest of the engine is not stock. It does produce high compression and high horsepower, but like Joe said I do suffer from lack of flow through these heads. That's why I want the edelbrock performers...I think I'll boost my power up significantly.

The #5 heads on my 455 were built by a shop which designs racing engines. They installed larger valves, etc.