72 Olds Project

Hello everyone. You may have seen that I am looking for a set of stock exhaust manifolds for my 455 build. We got the motor and transmission installed. Kept the headers in the engine bay before hooking everything up. Well, the passenger side header sits right on the frame and probably would not be able to get a gasket in to tighten it up. The drivers side will not even make it to the 1st port. It is about an inch short as the first bent tube on the bottom is hitting the frame. Does anyone know if maybe I have a set of 350 headers and not actually the 455's? I got them off of Ebay and they do not have any numbers. Also take into consideration I am using 350 engine pads and mounts. The motor seems to sit perfectly in the bay without any trouble and plenty of clearance valve cover/booster wise. Thanks

72 Olds Project

I will get a picture later of my headers. Thanks

TripDeuces

I had a set of Hedman headers on my 70 Cutlass S with a 455, they fit fine.

72 Olds Project

Good to know Trip. I know it would help if I could see the ones I have, but at work currently. I went to Summit's web page and pulled up a 350 and 455 header. To me it does look like the first tube is shorter and drops down before the 455's (driver side). That would make sense why it is hitting right on the frame and no way to get it close. The first is a 455 and the second is a 350. Thanks

455man

I got a pair of used headers for my 350 in my 72 supreme. They were tight. I dropped a 455 in and used the same headers. Tight but fit. I'm going to try to used the same headers on my 72 Cutlass with my 455.

TripDeuces

You'll notice the distance from the first vertical tube to the front of the flange looks longer on the 455 one. (Maybe it's an optical illusion or a bad pic but it looks longer to me) BBO need to be a bit longer because that port sits about 1 1/2 farther forward due to the block being longer.

72 Olds Project

Exactly! That is what I was thinking too Trip and that would give me the length I need to not hit the frame. I think I got sold a set of 350 headers and the person said they were 455's. Though I wonder how you were able to get yours to fit 455man? I would have to crush the entire first pipe to get it to fit. haha Odd. The frames should be the exact same on those years right?

72 Olds Project

Now let me ask a very stupid question. Could I possibly be in the wrong mounts on the block? We used the back 2 bolts and there was one in the front. Does anyone recall if that is correct? Wow that would really ruin my day if it was something that dumb. Thanks

joe_padavano

Yes, that is correct. The center and front bolt holes are only used on the 64-70 full size cars and the 73-74 Omegas due to the rear steering linkage location (and thus the forward crossmember location).

By the way, every header manufacturer routes header tubes differently, so there is no good way to compare photos of headers from different manufacturers.

72 Olds Project

Thanks Joe. I was hoping you would comment on this. I figured you knew which bolt holes are correct. Hmmmm.....I will do more investigating tonight. By the time we got finished it was already getting late. I just know the set I have are impossible to fit. The passenger side could be made to fit with some adjustment, but the driver side no way. I remember doing headers on my 68 GTO convertible clone I had and putting headers on it was a PITA. Oh yes and before anyone says....I am using brand new mounts

Oh and both of those headers are the Flowtech versions from the site....so they should be similar. I am sure mine are a cheap set, but I remember they did not have a name on them

TripDeuces

It's been explained a million times on these forums but the key to the engine/frame mounts is to use the matched pair. In other words both SBO engine and frame mounts or both BBO engine and frame mounts. Don't mix and match, or would that be mismatch? Lol

72 Olds Project

Haha Oh I did lots of research Trip before doing all of this. I even sent Joe an email a while back just making sure. Sometimes when you read too much then paranoia sets in. Then you read more from other people saying that is incorrect and they are right. I even sent an email to an "un-named" company to check on mounts. They said they would not use the 350 ones when many others said they were fine to use as long as you use the 350 pads. Go figure They look to have mounted perfect for me...just this header dilemma. Joe did warn me though about that too. LOL

72 Olds Project

Okay...finally got pics of my headers and sure enough you can plainly see that I have Olds 350 Headers. I guess a lesson from Ebay kids. I still worry though that 455man said his fit no problem using 350 Headers on his 455. Hope I dont make a $125 mistake. Well...I guess I have Olds 350 Headers for sale. Anyone?

455man

Keep in mind what Joe said. Different brands fit differently. Mine were a pain to put on but they fit. No idea what brand mine are since I bought them used.

72 Olds Project

Very true 455man. I ordered the Flowtech 455 version and will find out this week if they fit or not. I will keep everyone updated. Thank you

bonnevillegreg

Partially on this subject...

Hedmann and Hooker both make headers for a '72 Cutlass (350) but, they also both specify that said headers will not fit a Cutlass Supreme.

Anyone know why?

Sales reps for distributors were mystified and inquiries to Hedmann and Hooker have as yet gone unanswered.

TripDeuces

It's an old wives tale Bonnevillegreg. No one knows how that rumor got started but it never dies. I've heard it since the 70's and it still persists. They fit fine as I had a 70 Cutlass S with a BBO in it and Hedman headers. Ran it that way throughout the 70's and 80's.

72 Olds Project

And to add...if you look at the Flowtechs on Summit it says they will not fit offset engines. Which cars had an offset engine? Are they maybe speaking of the ones Joe mentioned earlier? The front bolt mount kind?

InfoJunkie

A few years back I had a customer ask for a Borla exhaust system for his vehicle. His year was not listed but the previous year was and he informed me they were the same body. I called Borla and was informed that even though they were the same body, Borla had not put a system in that body so they would not claim that it fit. Maybe Hedman, Hooker, and other companies have never installed headers in a Supreme so they claim the headers do not fit. I can tell you that Hedman Hedders for a 1969 A Body with a 455 fit great into a 1977 Omega subframe with a 455 but I have never seen that listed in any Header catalogue.
In my 1970 Cutlass originally with a 350 I put in a 455 using the pads and mounts from the 350. I bought Hedmans for a 455 Cutlass and had no problem fitting them.

1969w3155

Off set engines are also a myth.

svnt442

They also fit the F body cars when you put an Olds engine into them. I helped a guy out with some headers in about 1992 that was putting a 455 Olds into his T/A and they fit like a glove.

bonnevillegreg

I've been under one (or two, or thr...) Cutlass' and I can't see any significant difference in clearance between one or another with a 350.

The only thing I can think of is that perhaps there is some obscure optional feature available on some Supremes that would reduce the clearance somewhere, and to err on the side of fewer customer phone calls, they just say no go?

72 Olds Project

Okay everyone. Just an update on the headers. I got a set of the Flowtech 455 Headers from Summit and they actually fit. The bad thing is the driver side is very close to the steering shaft and a corner is barely hitting on the header, but they fit. Passenger side went on perfectly. So someone did list those headers on Ebay to fit a 455, but clearly made for a 350.

83-425

i know the 350 moter mounts are 1/2 lower than the bb mounts,i set the 2 mounts on my 72 frame and measured ,needed all i can get with a bb and tall intake,hope this helps.

joe_padavano

FYI, you are responding to a thread that's been dead for a decade. Also, please review this thread about motor mounts.