had an exhaust leak on the front side of the motor, so I pulled the head to take a look. Found out both bolts on the forward-most cylinder had broken, along with a crack in the manifold where the 3rd cyl is welded to the main pipe of the manifold. Any advice on this. I'd rather save the expense of aftermarket manifolds, so my question is whether welding them up will work. Anyone have experience with this?

Also, I see comments regarding "hogging out" the inside of the manifolds. If I do this, is there any HP gain? They look horribly restrictive they way they're made. Thanks for your ideas...

lots of people weld the cracked manifolds back up/ or beef up the welds on non-cracked manifolds. they key is to bolt them to a flat surface such as an old head, or atleast to another manifold, to prevent warping of the mating surface.

quote Originally posted by brad460: They look horribly restrictive they way they're made.

as far as hp gains on porting out the manifold....well i think you answered your own question. they are pitiful the way they were assembled.

The stock manifolts are 410 stainless, that requires a specific filler metal, I think 309, and they need to be TIG welded. Bolt them to a head before welding, then find someone with a large belt sander that you can use to sand the flange faces flat again. While they're off you should at least grind out the restriction where the two port tubes weld to the main tube, it's obvious what needs to be done once you look inside the port. BTW, most local machine shops will give or loan you a junk 2.8 head to use to bolt the manifold to.

JazzMan

I just did my manifolds. Wasn't as bad a job as I originally thought. I just took my manifolds to a local muffler shop and had them weld them up. They charged like $30 and did it while i waited. I had a friend who would have done them for free, but I felt better about paying someone that I might could hold responsible if they warped the manifolds. I also ground out the restrictions after having them welded. I'm not sure it made any difference in HP, but it sure sounds better.

I did this repair on mine this summer. I used my MIG welder and 100% argon gas, KT Stainless wire. Worked ok but I'm glad it's where you can't see the weld. Be sure to have the manifold bolted to a jig or a head. I've amazed my self in the past as just how much a tube will warp!

As for the porting, did that too. also the Y pipe. Not sure if it made alot of difference. Haven't rechecked against my G-tech meter yet.

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86GT Daily Driver
It's my work car. All I ever do is WORK on the damn thing!