BritishV8 Forum

Does anyone know what diameter the exhaust head pipes off of the manifolds were on a 1964 Buick 300?  I measured the head pipes from an Olds 215 and they were  1.625 in.

I have to figure out exhaust for my Astre project with  64 Buick 300 exhaust manifolds..

I have Mufflers that are 2in and would like to do the exhaust in 2 in. But that little raised built-in donut in the manifold itself is 2 in in diameter.  I'm thinking I will need to come off the exhaust manifold with a smaller pipe and then flare out to 2 in.

Just curious if thd headpipe sizes were the same between the 300 and the 215.

Here is what I got.

Olds 215 manifolds..

3 inch Bolt spacing.

Donut area od 2 inches

ID of outlet 1.5 inches.



64 Buick 300 manifolds.

3.5 inch bolt spacing

Donut area OD 2.25 inches.

I'D of outlet 1.75 inches.


So would the stock 300  headpipes have been 1.75 inches ID?

OK..Just got verification from someone with a stock 300 in a 65 Skylark...They are 1 75 inch.

The Mufflers I have are two inch so I'll have to figure out with the exhaust guy how to transition. I'll also have to try to locate the proper size and style of clamp to bolt the pipe to the manifolds.