455 exhaust manifold problem

cowboyup1248 · 04-12-2007, 09:37 PM

I am currently putting a beefed up 455 in my '79 Trans Am, but cant seem to find any exhaust manifolds for it for a decent price, I can find 350 manifolds. I know 403 manifolds will fit on a 455, but what about the 350's? any help on this matter will be greatly appriciated.

2blu442 · 04-13-2007, 05:52 AM

The 350 manifolds will bolt up, but not breath as well as 455 manifolds. Yes, the factory dual exhaust manifolds are very expensive, something we have to suffer with being Olds fans! John

joe_padavano · 04-13-2007, 06:47 AM

I know that funds are always an issue, but given the effort you're going through to get more HP, why do you want to restrict the motor with the small block manifolds. If this is a temporary thing until you can afford W/Z manifolds, fine. The only problem is that the factory manifolds are designed so that the exhaust pipe flanges are in the same place with each motor. In other words, if you use a small block manifold on a big block the pipe flange will be higher than normal due to the taller deck height. Just something to consider.

cowboyup1248 · 04-13-2007, 09:09 AM

yes, funds are tight right now. I wanted to put the small block manifolds on there so that I can drive the car until I have the money to either buy the right manifolds or a set of headers for it. I ended up having to make motor mounts for it because I couldnt afford the $140 ones from classic industries. Thanks for the info, this should help me get it running temporarily.

the_boat · 03-31-2008, 06:51 AM

Hello, it looks like you and I are looking for the same parts. Have you tried Thornton Reproductions? I am trying to find exhaust manifolds for my 455. So far, that is the only place I have been able to find any. If you do happen to find some somewhere, please let me know where. Good luck!

Rallye469 · 03-31-2008, 09:10 AM

Any access to a salvage yard? ebay?
I can't believe a set of manifolds for a 455 are that hard to come by.
Even if they're single exhaust manifolds with a cross over...
just weld up a cap on the extra hole and run duals from the exiting holes.
I really think Joe is right...you do not wanna put 350 manifolds on a 455.

Oldsguy · 03-31-2008, 09:52 AM

I am going to do it...........long enough to start fabricating fender well headers is all. Small block manifold is the only thing, except straight out horizontal headers, that will fit on the driver's side in my application.

Olds64 · 03-31-2008, 03:05 PM

Here is the web address for Thornton.

http://www.themotorcompany.com/Thorn...p-1-c-108.html

04-12-2007, 09:37 PM	#1 (permalink)
cowboyup1248 Junior Member Join Date: Apr 2007 Posts: 2	455 exhaust manifold problem I am currently putting a beefed up 455 in my '79 Trans Am, but cant seem to find any exhaust manifolds for it for a decent price, I can find 350 manifolds. I know 403 manifolds will fit on a 455, but what about the 350's? any help on this matter will be greatly appriciated.

04-13-2007, 05:52 AM	#2 (permalink)
2blu442 Senior Member Join Date: Sep 2006 Location: Medford, Oregon Posts: 853	The 350 manifolds will bolt up, but not breath as well as 455 manifolds. Yes, the factory dual exhaust manifolds are very expensive, something we have to suffer with being Olds fans! John __________________ 1964 Cutlass Factory 4spd 1965 442 4spd 1967 442 Auto 1967 Cutlass Convertible 1968 442 Auto 1969 442 W30 Auto 1970 442 4spd 1971 Cutlass Flat Top Wagon 1973 Che*vy 3/4 Ton 454/TH400 Tow Vehicle Only the tow vehicle is finished!

04-13-2007, 06:47 AM	#3 (permalink)
joe_padavano Moderator Join Date: Mar 2007 Location: Northern VA Posts: 1,734	I know that funds are always an issue, but given the effort you're going through to get more HP, why do you want to restrict the motor with the small block manifolds. If this is a temporary thing until you can afford W/Z manifolds, fine. The only problem is that the factory manifolds are designed so that the exhaust pipe flanges are in the same place with each motor. In other words, if you use a small block manifold on a big block the pipe flange will be higher than normal due to the taller deck height. Just something to consider. __________________ Joe Padavano 64 Jetstar 88 Conv 66 442 L-69 Conv 68 W-30 69 H/O 69 442 70 W-30 72 442 84 Custom Cruiser 86 Caprice wagon (w/307 Olds)

04-13-2007, 09:09 AM	#4 (permalink)
cowboyup1248 Junior Member Join Date: Apr 2007 Posts: 2	funds yes, funds are tight right now. I wanted to put the small block manifolds on there so that I can drive the car until I have the money to either buy the right manifolds or a set of headers for it. I ended up having to make motor mounts for it because I couldnt afford the $140 ones from classic industries. Thanks for the info, this should help me get it running temporarily.

03-31-2008, 09:10 AM	#6 (permalink)
Rallye469 Senior Member Join Date: Feb 2008 Posts: 223	Any access to a salvage yard? ebay? I can't believe a set of manifolds for a 455 are that hard to come by. Even if they're single exhaust manifolds with a cross over... just weld up a cap on the extra hole and run duals from the exiting holes. I really think Joe is right...you do not wanna put 350 manifolds on a 455. __________________ '70 Rallye 350 '65 F-85 http://www.youtube.com/watch?v=CCw-JmwNGZQ

03-31-2008, 06:51 AM	#5 (permalink)
the_boat Junior Member Join Date: Mar 2008 Location: manhattan, ks Posts: 13	Hello, it looks like you and I are looking for the same parts. Have you tried Thornton Reproductions? I am trying to find exhaust manifolds for my 455. So far, that is the only place I have been able to find any. If you do happen to find some somewhere, please let me know where. Good luck!

03-31-2008, 09:52 AM	#7 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 2,967	I am going to do it...........long enough to start fabricating fender well headers is all. Small block manifold is the only thing, except straight out horizontal headers, that will fit on the driver's side in my application. __________________ Dan '46 2 door

03-31-2008, 03:05 PM	#8 (permalink)
Olds64 Landyacht Club President Join Date: Jul 2007 Location: Lawton, OK Posts: 1,590	Here is the web address for Thornton. http://www.themotorcompany.com/Thorn...p-1-c-108.html __________________ "Some men are Baptists, others Catholics. My father was an OLDSMOBILE man." Ralphie Billingsley A Christmas Story 1983 "We rei-eign, supreme, ooooh god! Burrito supreme, and a chicken supreme, and a CUTLASS SUPREME!" Tenacious D 2007

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