Are 350 and 455 headers interchangeable? More specifically, will the pipe from a 73 350 fit onto a 72 455?

Thanks,
Ted

 

As far as I remember, the last time I tried doing that, the small block primaries hit the steering rack... The big block primaries are tucked in more. This was 4 years ago, mind you, with a set of Sanderson shorty headers, someone else may be able to chime in. What brand are they? That may matter....

 

Physically they will bolt on to the bigblock, but you'll have an assortment of possible issues like starter interference, steering shaft interference, oil filter and or housing interference. Motor mounts, frame, floor of car.

All depends on what chassis youre installing them in as to wether you can work around the issues

 

The 73 350 is in a 72 Cutlass S with headers. I want to switch out to a 72 455 .
Will the exhaust ports line up or will i have to do a lot of tweaking,...I was hoping I could set in and headers would be fairly close....

Thanks,
Ted

 

As with the factory exhaust manifolds, ALL Olds headers use the same exhaust port flange and will physically bolt to BBO and SBO heads. The problem is that the headers are different based on the different deck heights. Also, different size motors need different size pipes.

Ask yourself this question: Would header manufacturers waste the money to develop and stock different headers for BBOs and SBOs if the same ones fit both?

 

They will fit but it takes some work/denting to get them in. Mine were used $40 headers so I didnt mind some minor dents.

 

I've had both SBO and BBO headers setting side by side, and they are different lengths. I just went with BBO long tubes when switching to a 455, and didn't have any problems. Didn't have any problems selling the SBO headers, as had a new pair in the box. Wouldn't have bought a new pair of BBO long tubes, if didn't think I needed them.

 

From what I've been seeing they attach but aren't the same shape.....or tube size. The SB are 1 5/8 usually and the BB are 1 3/4. I need some mid-length for the '67. The full length almost drag the ground.