nycab

iTrader: (7)

--- Scroll down for after pictures. ---
I'm doing a second gen trans am ls1 conversion and I got a set of 4th gen headers cheap. They almost fit except for the collectors. The pictures show the dilemma. The drivers side angle is obviously not good and it impacts about 1/4 inch. The passengers side angle is fine, but impacts maybe 1/8 inch.

Should I just bolt them to the engine and try cold bending them in place? If so, what's the best way to go about it?

Or should I just cut the dirvers side collector right after the O2 bung and weld a mandrel bend that fixes both the angle and the interference and notch the frame slightly?

Note: these pictures are of my engine test-fit into the frame rails. The mounts are installed. I wish I had pictures of the engine placed perfectly, but the engine is actually sitting a tad bit too far towards the drivers side - which is why the passengers side collector seems to barely fit, when really it interferes about 1/8in. It's obviously sitting a bit too high as well...

DaveX

You might be able to bend them if you take them off the motor and heat them up where you want them to bend. I wouldn't try to bend them while attached to the motor. The mounting bolts are going into aluminum. I think cut and weld would be a much better option. That pic showing the right side presents a problem though. Even if you get the collector to clear, the primaries are going to bang on the frame with the motor running unless you run sold mounts (not polys).

Or better yet, just get some headers that fit, that is what I would do.

TheSilverOne

iTrader: (22)

yeah everything looks beautiful except for those rusty headers. i would definitely get some that fit properly.

nycab

iTrader: (7)

I would agree with you about them being rusty, etc. and just getting ones that fit. Unfortunately, my original plans for the car aren't in the card financially at the moment, and I really need to get the project moving. At this point, I want to have a car that runs--not one that sits for another 3 years.

I got these headers for about $100. If I can make them fit for < $150 in labor and a one $20 mandrel bend, then I will have spent far less than any header "that fits." In fact, throw in a pair of 3in-2.5in header adapters, a universal x-pipe kit and two mufflers, and I've got an entire exhaust system cheaper than a pair of headers "that fit."

As far as banging, the engine torques down toward the drivers side, right? So if I cut the collector right behind the O2 bung and welded a 20deg or so mandrel bend there, I'd have quite a bit of clearance - probably 1/2 - 3/4in I think. If I can "tweak" 1/2in out of the passengers side, I'd be good to go there. I think the primaries have maybe 1/4in of clearance. I wouldn't be terribly opposed to heating up the offending one a tad and pushing it over. or "persuading" it with a socket and a BFH. I might also be able to move the engine back a bit.

jimmyblue

iTrader: (11)

Get a bunch of pieces of 1x2 or 1x4 wood cut short,
for shims. Loosen all the joints in the exhaust but
just enough for wiggle room. Use a crowbar to
jack the exhaust away from close points and get
the shims in there so you have guaranteed clearance.
Then put the floor jack to the lowest point, get it
to lift the body and go tighten up all the clamps.

You may want to hose-clamp a piece of heater
hose (clamp band inside hose) to where the most-
outboard passenger's side pipe runs closest to the
floorboard.

nycab

iTrader: (7)

You're saying to bend the headers in place? Wouldn't that strip the aluminum threads?

jimmyblue

iTrader: (11)

Not bend the headers, just the slip-joints. Of course
if the headers are a real mis-fit, and not just a poor
design / tolerance, you may have large problems.
But this is what I had to do on my exhaust to get
it to not bang etc.

nycab

iTrader: (7)

ok, took me a while to get around to them, but just got them back from the welding shop. bend the passenger's side inward. cut and rewelded the drivers side. welded 3-bolt flanges to both.

cost: $140 for labor, $7 for flanges

Now I just need to get the rest of the project put together, then i can bead blast and send them off for ceramic coating.

check it out if you wish.