[steel dragon]

Hey,
i was looking for some advice on headers i should get for my 455 that im going to put in a 79' TA. I was told they would not fit is that right? thanks!!

[77Brawler]

you wont have any problems, as long as you get a decent set, the best proof i can give u is that a 400 and a 455 use the same headers, and 400's were available stock in your 79,and probably the most commonly swapped motors in 79-81 birds, unless you get a real cheap set that are poorly built, their a easy. I have hedmans on my 77, and have been happy with them as a whole.


Also go long tube, i've seen more than a few dyno test that showed almost no gain with shorties compared to stock.

[steel dragon]

Well i know that the 455 pontiac will fit with headers but i am useing a 455 Olds motor and am told there was a differnce in space. (keep in mind this is my first build )

[77Brawler]

Ah ok now i see why people are telling you you'll have problems. and their right, unlike the olds 403, the olds 455 is a true big block, and its going to give you two problems. #1 from what i've been told its if you want to keep the shaker it has to be fixed to the hood not the carb, theres not enough clearance to mount it on the carb#2 the guys i've talked to that have done this swap all told me the same thing, no one makes headers for this and the 403 ones arent the same, which leaves you two options, the easy one of using the stock manifolds and having exhaust run or making or modifying another set of headers to work.

can i ask why your using a olds and not a pontiac? the pontiac would be a straight swap?

[joe_padavano]

Originally Posted by 77Brawler

Ah ok now i see why people are telling you you'll have problems. and their right, unlike the olds 403, the olds 455 is a true big block, and its going to give you two problems.

I'm not sure what a "true" big block is, the the only external difference between the 403 "small block" Olds motor and the 455 "big block" is the taller deck height on the 455. Unlike Chevy or Ford, the Olds motors are the same basic design. It's more like the Chrysler B and RB engine families. The BBO does use larger main and rod bearings, so the cranks don't interchange, but cams, lifters, rockers, timing set, distributor, oil pan, brackets, accessories, etc all swap. The intake is about 1.5" wider due to the taller deck height.

#1 from what i've been told its if you want to keep the shaker it has to be fixed to the hood not the carb, theres not enough clearance to mount it on the carb

That's probably true, again due to the taller deck height. You might be able to rig up a dropped base air cleaner housing to make up the difference. The other thing to try is to get an early Toronado intake manifold. The first gen Toro used an intake with a sunken carb mount to clear the sloping hood on those cars. There's about an inch difference as compared to a stock RWD 455 intake.

#2 the guys i've talked to that have done this swap all told me the same thing, no one makes headers for this and the 403 ones arent the same, which leaves you two options, the easy one of using the stock manifolds and having exhaust run or making or modifying another set of headers to work.

The 403 headers will physically bolt to the 455, but the taller deck may cause clearance problems. I would check with Mondello or Dick Miller. This is actually a fairly common swap into the 403 F-body cars. At worst, you should be able to use 403 headers and lengthen the primary tubes by about 1".

can i ask why your using a olds and not a pontiac? the pontiac would be a straight swap?

Actually, if the car had a 403 initially, the Olds 455 is an easier swap. The brackets, mount, starter, accessories, etc all bolt right up. A Poncho swap would require changing all these parts. Certainly not impossible, but it's just one more thing you have to do.

[77Brawler]

I've never tried the swap myself, and im not a olds guy, the info i got was from talking to a couple guys i consider reliable that are into the olds, so if im mistaken i aplogize.

as far as the poncho being a easier swap, i meant the parts will be easier to find no trying to get things to work or trying this and that.

[joe_padavano]

Originally Posted by 77Brawler

as far as the poncho being a easier swap, i meant the parts will be easier to find no trying to get things to work or trying this and that.

Well, again, if the car had an Olds 403 originally, an Olds 455 is almost a bolt-in. The Poncho 455 requires sourcing and swapping a lot of small parts.

[matt69olds]

Mondello, Dick Miller, Hooker, and Hedman Headers all have 455 headers that fit the f-body. You can use 403 headers, you have to beat the tube for cylinder #8 to fit around the heater box. If I rembeber correctly there was also clearance issues with the firewall. All the problems are related to the difference in deck heights between 403 and 455 engines. My advice would be to get the right headers. By the time you dent the tubes to fit, they probably dont flow any better than manifolds. Dont let the Pontiac faithful make you feel bad about the Olds engine, they run very well with the right mods! This is in no way meant to disrespect Pontiac engines. I love the BOP cars and drivetrains! Good luck!

[steel dragon]

Well would you have any suggestions on what headers i should use (part #) that would work the best and have to do very little work on like denting or bending then that would help a lot. Thanks

[matt69olds]

I dont have any catalogs handy, I know for a fact that headers are avaliable. The set I installed in my freinds 79 TA ( fondly nicknamed the Trash Can)were made by Hooker and were sold by Mondello. They fit very well with no dents needed. Good luck!