# Random exhaust manifold question



## 67lemans (Oct 30, 2009)

I've always wondered if there were any differences in how the factory exhaust manifolds flowed on the A body cars. Not talking about the Ram air ones, or round ports, but just the plain ole factory logs. Did 455's have bigger logs than 326, 400 bigger vs 350 and so on, or were they basically all the same size on the inside?


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## 1971LemansWisc (Apr 18, 2021)

I’m not sure I can answer your question, but I can add some data.
Attached are Images of two different (same side of Engine) Pontiac Exhaust Manifolds. 
The top is Casting 490143 Date Code F222 (June 22, 1972) – 6 bolt. 
The Bottom is Casting 480602 Date Code E042 (May 4, 1972) – 4 bolt. 
Wallace Racing has the 490143 as 1971-74 350/400/455.
The 480602 is listed in 1972 as 400/455. 
To me, and I’m not an expert, the Casting 490143 for 1972 looks to be the Standard Manifold across the multiple Displacements. 
For all practical purposes the Exhaust Runner/Ports portion of the 490143 and 480602 Castings are identical so I would guess the volume to be same. 

Randy


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## 67lemans (Oct 30, 2009)

Thanks! Good Pics. I am thinking the same thing.


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