I am currently doing a frame off restoration of my '68 olds cutlass convertible. I am building a 455ci to drop in it, and I cannot find exhaust manifolds for it. All of the manifolds I can find are not compatible with convertibles. I suspect this is because the convertible has a boxed in frame versus the open channel frame of the hardtops. Anyone know of manifolds or even headers I can use for this? Thanks in advance,

Jim

 

That doesn't seem right to me. Never heard that before. That doesn't sound like Olds engineering to me.
I'll be watching this post,
Thanks

 

Welcome to the sight.

Order for a '68 with a 455. Just don't tell them it's a convertible.

https://classicoldsmobile.com/forums...s-headers.html

Norm

 

Every parts supplier I have contacted has told me the manifolds they have fit everything but convertibles.

 

these are pretty.
http://gawain.membrane.com/~thornton/manifold.html

 

https://classicoldsmobile.com/forums...e-headers.html

Norm

 

Chet,

I also responded to your post on the AACA website. I'd like to know which parts vendors are telling you this, because they are flat wrong.

Let's start with facts:

1) the Olds 400 and 455 motors are externally identical
2) Olds used the same manifolds for the convertible and the hardtop and the 400 motor was absolutely factory installed in both.

It doesn't take much logic to figure out that this parts supplier is clueless.

As I noted on the other forum, the convertible and HT frames, motor mounts, firewall, etc are identical from the firewall forward. Headers and manifolds for the hardtop also fit the convertible. This has been proven time and time and time and time again. Dozens of folks on this site will be happy to share photos of their convertibles with headers or manifolds.

 

Joe, I'll be straight with you. The restore isn't mine, but a friend of mine who is so computer illiterate that I won't even let him stand near my desk while I am using it. It sounds to me that another friend of his hit the big internet suppliers, like Jegs, and......well, I'm drawing a blank on the other ones he told me about. I'll ask him to write them down and I'll post it up here.

 

No need to. The bogus information came from the manufacturers.

Norm

 

Good stuff Norm!

 

Thanks.

Hooker's online catalog says their #3101 will not fit Supremes, but nothing is said about convertibles. Don't ask why I was snooping there.

Norm

 

I'm aware of the header problem (and some manufacturers do say they don't fit convertibles), but this was the first I'd heard of an issue with manifolds, which is even more ridiculous.