[Kawidood28]

Hey folks I’m new to the forum ( not new to cars ) I just sold my 65 lesabre and picked up an 89 caprice wagon. The car needs very little but one of those few things is a passenger side exhaust manifold. The 307 is everywhere but I can’t find new manifolds for it to save my life. Any suggestions? My existing manifolds don’t look like they’re worth fixing they’re pretty crusty. From my understanding the manifolds are mostly interchangeable between the 307-455 but I’ve seen some that don’t have the second outlet on the passenger side for a crossover.

 

[sheila]

Welcome!

 

[Kawidood28]

Welcome!

Thank you!

 

[Brhatweed]

Olds 260 to 455 all share a common manifold pair except the front drive Toronado & Elanza spec 455/403, 1966 to 1984 were cast iron and 1985 to the end were the round port TEMS that were used on the 2nd generation 307 roller motor. All the 1980 and later gas engines have the O2 port, 5.7 diesel has only the boss you can drill & tap and ALL rear drive Olds manifolds use the 2 port pass side and xover pipe. Pre-cat Dual exhaust had a blocking plate for the inlet port and used the common single exhaust system while the driver side was a specific, post-cat was a split behind the converter. AIR is pumped into the heads above the exhaust ports using stainless tubes in the path.
Olds V8 motors have been out of production since 1990 and I doubt the NOS supply is all but non existent, I've had good luck media blasting and using the cast iron coating from Year One for Olds restos

 

[Kawidood28]

Olds 260 to 455 all share a common manifold pair except the front drive Toronado & Elanza spec 455/403, 1966 to 1984 were cast iron and 1985 to the end were the round port TEMS that were used on the 2nd generation 307 roller motor. All the 1980 and later gas engines have the O2 port, 5.7 diesel has only the boss you can drill & tap and ALL rear drive Olds manifolds use the 2 port pass side and xover pipe. Pre-cat Dual exhaust had a blocking plate for the inlet port and used the common single exhaust system while the driver side was a specific, post-cat was a split behind the converter. AIR is pumped into the heads above the exhaust ports using stainless tubes in the path.
Olds V8 motors have been out of production since 1990 and I doubt the NOS supply is all but non existent, I've had good luck media blasting and using the cast iron coating from Year One for Olds restos

That’s some good information thank you. Sounds like I should keep my eyes peeled for an 85+ set of manifolds just to keep it apples to apples or if it comes down to it I could blast and braise the old ones.

 

[Brhatweed]

The 85+ spec manifolds are formed and welded steel with what looks like a round "plug" on the front end, these are the round port manifolds used on the fast burn 307 roller cam motor. You can replace them with the older iron square port pieces as they will bolt up and work just the same, the irons actually flow much better but they're not as sexy.

Cool thing about that Olds 307 is it will outlive the Chev 305 and drink less along the way, I know I'm going to start a fire with that statement but so be it. Been doing Olds motors since the early 80's and while I like the Caprice & Impala Im not going to cave into the bowtie smallblock, I'm basing this on experience with both.

 

[mick1724]

The 85+ spec manifolds are formed and welded steel with what looks like a round "plug" on the front end, these are the round port manifolds used on the fast burn 307 roller cam motor. You can replace them with the older iron square port pieces as they will bolt up and work just the same, the irons actually flow much better but they're not as sexy.

Cool thing about that Olds 307 is it will outlive the Chev 305 and drink less along the way, I know I'm going to start a fire with that statement but so be it. Been doing Olds motors since the early 80's and while I like the Caprice & Impala Im not going to cave into the bowtie smallblock, I'm basing this on experience with both.

Pull the 307 OLDS and drop in a 455... More fun than any small block! You will Piss people Off! So don't blame me!
Use headers for a 1976 cutlass 455 and massage the drivers side too fit... Easy non axe murder! Set the motor in with out the oil filter adaptor / install after headers.

 

[Brhatweed]

Done many of these conversions from the 5.7Dx during the 1980's. Pontiac 455's, Buick motors and a few Cadillac 472/500 motors have found their way into these.