TAC Tech => Mechanical => Topic started by: Bale9 on February 12, 2024, 02:44:13 PM
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Hi All
Struggling to get a proper answer on this...
I have a 1979 Trans Am with a Olds 403 and currently running Hooker long tube headers and with my T/A being lowered the long tubes hang down way too far and scrape on everything.... My intention is to raise the rear a little as it has sagged more then expected and then install 17" snowflakes when they eventually turn up.
I'm also intending to take the long tube headers out and install something else, I have seen Hedman Headers #58160 on Summit that suits a Olds 403 however they are saying it won't fit a Trans Am however there is no real reason behind why...
https://www.summitracing.com/parts/hed-58160
So I'm hoping someone here has tried it and can tell me if it's going to work? I understand that I'm going to have to install a new exhaust pipe from the headers down.
There was a comment in the Summit questions that it may fowl on the chassis, i'm doubting this as there appears to be enough room for the Hooker headers to fit so don't know how these won't.
Thanks
Bill
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Sorry I can't offer any insight as to what headers will fit your car with an Old's 403. But many years ago, I installed a set of long tube headers on my 1973 TA with a Pontiac 455. While the car ran better at the strip with open headers. Through the exhaust system on the street, I could tell very little if any difference. If only driving on the street I think factory manifolds are the best way to go. This probably not the answer you are looking for.
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Hi
My plan B is going to be install the factory manifolds however I was hoping for a nice looking set of headers instead of the cast iron manifolds.
This T/A will never see the track or be driven hard enough to need a set of race headers, it is more of a weekend cruiser. So all I'm looking for it to look and sound good.
I know there is aftermarket Thornton cast iron headers available however i may as well sandblast and ceramic coat my factory ones.
https://www.ebay.com/itm/184078906598?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=INnIVUelRZe&sssrc=2047675&ssuid=gDDSuXCsRUO&widget_ver=artemis&media=COPY
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Thornton also do shorty headers, more for when nothing fits and perhaps take all that collector heat surface area away from under the floor. I think Mike Olds403 had a set, not sure if ever tested or installed in vehicle.
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I have the Thornton Olds small block manifolds. They are a bit larger than the factory manifolds plus they eliminate that stupid cross over port. Be forwarned that the passenger side manifold will not seat unless you use two gaskets. This is because the manifold interferes with the 403 cast into the block.
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I have never heard anything really good about headers on these cars, unless of course its a true race settup.
Did you call Summit and talk to someone? When I was looking for the exhaust for my car (I was buying Pypes) there was a bit of confusion on my end as to the wording. The fine print was that a box needed to be checked that said the exhaust was intended for off road/track use only. Once I did that everything went through fine. This was because I was looking for a non cat system.
Just a thought.
I would second factory mani's though. I have raIII's on one car and they look stock and give good power. Stock on the other car that is not on the road yet. Very curious as to how they will compare.
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Looks like I'm going to have to drag the old manifolds out from under bench and get them ceramic coated or something.
I really don't like these long headers, they sound great and no doubt provide more power but I'm chasing for it to be functional on the road... Too many speed bumps around my area.
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Bill, even if only temporary, you could adjust the exhaust to suit stock manifolds so can be adjusted again in future when options come up. Obviously, you'd need complete new down pipes on both sides of smaller diameter and have to run them back to hopefully somewhere where the exhaust system began, only lifted. I have a couple of sets of the manifolds, crossover if needed, unlikely, but also a few of the original crossover caps to turn them into a dual system. Not all Olds used the crossover. Easy to make though, from a matching flange plate with no hole, to what most did back in the day, to simply cut the matching stock exhaust pipe after the join and weld a cap on what was left poking out.
Your car is also fairly low, only making the issue worse. Neither are an easy fix though.
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Thanks Ben.
I have my original ones here and I'm going to try and remove the broken studs in them. I think you are right though, I'll use it for now and see how it goes as i'm not in position to be pouring much more cash into the car for a while.
I'll run the down pipe from the original manifolds to the current exhaust and see how it goes.
If get stuck and I need some manifolds I'll contact you and see what we can work out.
Appreciate your help.
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Just some ideas for crossover capping. This is the GM version, it changed slightly over the years but did same thing. There used to be an aftermarket version too, was like a solid lump of cast iron of same thing rather than stamped.
Found one:
https://www.thepartsplaceinc.com/images/productphotos/EX2604T.jpg
(https://live.staticflickr.com/65535/53531200007_a1f825fbe6_z.jpg) (https://flic.kr/p/2pynoLg)Olds exhaust crossover cap (https://flic.kr/p/2pynoLg) by Ben (https://www.flickr.com/photos/196419001@N03/), on Flickr
(https://live.staticflickr.com/65535/53532520930_9e84b597d5_z.jpg) (https://flic.kr/p/2pyuaqN)Oldsmobile crossover exhaust manifold plate2 (https://flic.kr/p/2pyuaqN) by Ben (https://www.flickr.com/photos/196419001@N03/), on Flickr
Otherwise, ask around more of the groups with those that have headers installed. The local guys often don't know, most bought their imported car in the last 2 years already built and most know little about the details as didn't build them. Not their fault, just facts.