455 exhaust manifolds

[Atownsend]

Hey Guys I am near to having my newly overhauled 455 running now in front a beefed up and overhauled th350 with shift kit and a step up from stock on the torque converter for stall.

I have read a lot of posts on here regarding that headers are hard to find for our 76/77 generation cutlass 442 that do not require modification... I wouldn't want to buy a $600 set of headers and have to start cutting. Haven't had any luck at finding shorty headers either.

Ran across the Thornton reproduction w30 cast manifolds.

Has anyone bought a set of these and seen how well they work? How well they are made?

If they are good, do you use a gasket? I know the originals the manifolds were machined to match the head exhaust parts flat.

What do you all think?

[oldstofty]

Dont know anything about the Thorton Manifolds but I used the same headers that were one my 69 442 on my 77 cutlass. The only thing i had to do was jack up the car to clear the lower control arm. Once bolted in, there was no clearence issues.

[zodiacblue442]

My brother and I each bought a set of Thornton true dual exhaust manifolds for small blocks. The quality is excellent and I wouldn't hesitate to buy some for a big block. Use the FelPro gaskets between the manifold and head. It's good insurance to not have an exhaust leak. Personally I would buy the divided port dual exhaust manifolds and not headers. I hate headers because they usually leak, are hard to fit, and really cut down on ground clearance, but that's just my .02.

[oldstofty]

Personally I would buy the divided port dual exhaust manifolds and not headers. I hate headers because they usually leak, are hard to fit, and really cut down on ground clearance, but that's just my .02.

Agreed they can be a little more difficult than manifolds, but it depends on the application and what your trying to do. If your looking for performance, you will have better results from the headers, but if its a just a cruise in toy than I wouldnt bother with the headers

[W451973]

Headers for our cars really are'nt that much of a problem. Large tube, yes. Small tube, no. For extra horsepower then headers are the way to go. For a more trouble free exhaust then I would suggest the manifolds. Each has it's advantages and drawbacks.

[mdkingsley]

I have a set of ceramic coated headers for mine but am thinking about going with the manifolds for ease of operation and a stock look. I have heard those repro manifolds are good quality.

[Hurstolds1973]

I bought a set of the repop Thorntons for Rusty because I found a slight stress crack on one of the holes. Probably wouldn't have leaked or ever seen it but when your this far into a cluster fock why not! The look almost identicle in everyway I can see. Will be bolted on this weekend. I really like ths stock manifolds..... my2cents

[Atownsend]

Thanks for the input guys! Will go with a set of Thornton reproduction.
Haven't seen much good on headers for olds 455

[Hurstolds1973]

I got a few minutes to mess with them today after i dressed the motor. The Fel Pro gaskets set I have has 2 slightly different gasket sets. One set matches the exhaust holes in the heads exactly and the other set matches the manifolds exactly. What I am saying is the head side opening is smaller then the manifold opeings in the middle but same on outside. I dont know which set to use, I guess either way there will be a small amount of gasket exposed...... hmmmmm what to do.....

[cl442]

Yes i just bought a pair for my 350. Have not used them yet . i was told not to used gasket becaused they are new and not worp yet. had header but got to hot so i went ewith these

[W451973]

Joe. I think I understand what you are describing but without visually seeing it I'm gonna go out on a limb here and say use the ones that match the head. Just make sure to match them up to the manifolds so you won't have any leaks.

[Hurstolds1973]

I went with the larger FelPro set today. I didn't like th way the smaller set covered on the W side. The larger set sat nice on the heads and manifold without any gasket on the inside exposed.
Would you believe I forgot to put the dip stick tube in!!!!!!! I think I have to remove the manifold to get it in! dammm :cool:

[Atownsend]

Great pics of the engine! I used a different blue that came out lighter. Claimed it was Olds blue.
Like the black pulley's, I am painting my brackets for power steering, alternator, and a/c (if I put it back on) black epoxy.

May have to do the pulley's now after seeing yours!
Alex

[Doug Blake]

Smitty has the best headers, if you dont want manifolds.
www.mjproformance.com

[ragz442]

Man, that motor looks SWEEEET Joe!

[Hurstolds1973]

May have to do the pulley's now after seeing yours!
Alex
Thanks!
I did not powder coat them, all the pulleys and bracket were sand blasted and then semi gloss painted.

Todd , Thanks! Its taking so long. I read a little of the manual and do , then go back and double check it... Then fix what I messsed up 2 or 3 times! Man I'm SLOW! lol