I have had my heat exchangers off and on now about 4 times, trying to make sure that they are seated and tight. I have checked the copper gasket, put in new ones and still I get popping or back firing on decel.

Tonight I pulled the driver's side and flat filed the tops of the HEs to make sure I have a good surface. Nothing drastic, just trying to make it flat and smooth.

Is there any trick to getting everything buttoned up properly?

Anneal the copper seals before you bolt up the exhaust. Heat them until they just begin to glow, let them cool, and install. This will soften the copper and let it take an impression from the exhaust.

Oh, but how do I do that? I mean, do I heat them when they are seated or do I heat them and then push them up into the head?

Take them out, heat them as sww914 says, let them cool slowly (don't put them into water as a friend to me did ) , then install them
Heat makes the copper soft, pressure makes it hard... same thing is possible to do with the copper sealing to the oil plug if you don't have a new sealing at oilchange


EDIT: Don't reuse the crush washer, allways use a new washer at oilchange, I mentioned the method for the crush washer only as a example and what you can do when you are in some situation when you don't have a new washer (and the old one is made of solid copper), here in sweden we had regulations for asbestos since late 70s but there is of course other fillings in the market, those will not change with heat at all.

Sorry, I should have written something like this: "this procedure does not apply to the crush gaskets that have asbestos or some other filling, just the solid copper ones"

Check your intakes at the head. A leak there can make you think it's the HE when it's not.

Popping out the exhaust does not necessarily mean the HE to head junction is leaking.

To answer your question, you remove them from the head and use a propane torch. I always re-anneal the copper gaskets before installation, even when they're new. I make up a coat hanger... hanger for the gaskets and stick it in the vise. If your gaskets have any ridges on them, toss 'em and buy new ones. They're cheap...

I used two copper gaskets, instead of one. took care of it for me.

That's ABSOLUTELY the WRONG way to do it. Just makes another place for leaks to happen, and lessens the engagement of the nuts. File the pipes flat, doing both at the same time, so they're parallel. I clamp the HE to a bench and work across the 2 flanges until they're flat. Heating and slowly cooling the gaskets sounds like a good ides, although I've never done it. Pull the nuts up evenly, tighten them down, run it, retighten them when the system is hot. BTW, torching an asbestos filled copper crush washer as another poster suggested isn't something a professional would even think of.

The Cap'n

Do as the Cap'n says. Use one and only one copper gasket for each port.

I also tightened the exhaust nuts slowly in an alternating 'x' pattern to make sure the exchanger was being fitted evenly.
Here is a great link with picutures on the entire process.

Prepping and Installing Heat Exchangers

Also, Gint makes a good point. How do you know that the popping & backfiring is a result of an exhaust leak at the exchanger(s)? I had a huge exhaust leak at the exchanger due to a gasket not being seated properly, and my car never popped or backfired.
Are you sure you don't have any holes in the exhaust system (muffler included)?

I am pretty sure that there are no leaks in the exhaust otherwise. I bead blasted them and checked them over when I installed them. Obviously, I can't see under the HE tin, but I assume that they are solid.

I just installed my stailless HEs on my car last night with a new bursch exaust. got the kit from AA. I did not heat my rings first, I cannot run the car yet, I havent finished putting it back togeather on the top side. Is it going to leak gaurenteed?? cause I spent a good while getting it perfect straight and tight.

Don't worry about it jsayre914. Annealing is not necessary. If your surfaces were good, and everything was assembled loosely, then tightened up carefully in a crossing pattern like rjames said, you'll be fine. After it has heat cycled, check the nuts again like the Cap'n said - but don't over-tighten!

And exactly 'who in the world' suggested that? To be more specific, what copper crush washer is filled with abestos?

From a previous post by Challe:"... Heat makes the copper soft, pressure makes it hard... same thing is possible to do with the copper sealing to the oil plug if you don't have a new sealing at oilchange."

Thanks, I didn't catch that. I was pretty sure that an exhaust gasket like those that we are discussing here isn't an "asbestos filled copper crush washer."

I'll skip the argument about whether or not the oil drain plug gasket is filled with asbestos or not.

Can't you just get the copper rings from jake raby's store and be done with it? they come from him annealed.

Never had a leak with my header, although YMMV since i dont need heat in the devil's sweaty armpit(houston)

I'm not speaking for Jake, but I'll bet a beer he doesn't anneal exhaust gaskets.

Annealing isn't a bad idea. Softer copper forms easier. I just don't like people being worried because they think it HAS to be done.

Cap'n is absolutly right, torching an asbestos filled copper crush washer is absolutly idiotic, my post is now edited

I'd have to re-read this whole thread, but I don't think anyone said you "have to" anneal copper gaskets.

See post #11.
I just wouldn't want someone wondering if they had to redo the job because the gaskets weren't annealed.

Must be that time of the month again.

I need to redo it because I have a leak somewhere. Anything that helps reduce the leak is a good thing.

"I've applied some Loctite 518 to both sides of the copper rings to help the exhaust seal. You can also use weatherstripping adhesive or anything similar. All of the sealants turn to carbon from the heat and help to provide a carbonized seal. The loctite is nice because it's so tacky but I haven't used it enough times to say it's better than anything else."

from the link. any of you guys do this?

I used the glue you use to affix the hood logo on. it's from 3m and bonds metal to metal nicely. It helps you get everything seated and aligned without having to worry about stuff falling apart on you.