What is an "exhaust donut sleeve" used for?

[Timothy B.]

This is probably a dumb question. Several catalogs I have seen list as applicable to a 67 SB something called an exhaust donut sleeve. It looks like a short 2" or so piece of exhaust pipe swaged down on one end. I know what the heat riser is for, and I know about the FI heat riser plates without an actual valve, and I know what the donut packing is for to seal to the exhaust manifold. What the heck is this other piece for??? Were they installed on every car on both sides?

[bill stephenson]

Re: What is an "exhaust donut sleeve" used for?

-------Keeps the donut in place........Bill S

[Timothy B.]

Re: What is an "exhaust donut sleeve" used for?

OK, so help me out since I obviously aren't familiar with it. Does it slip into the exhaust pipe and then the packing goes around it, then the whole thing slides into the exhaust manifold? Is this a required part or just a part that isn't really needed and is often left off? I am just amazed that I have never seen one...

[John M.]

Re: What is an "exhaust donut sleeve" used for?

It slips inside the donut, and then slipped inside the exhaust pipe.

Regards, John McGraw

[Mike M.]

Re: What is an "exhaust donut sleeve" used for?

don't install donut without sleeve as it centers the donut which if slightly offcenter and hence allowing a little gas excape, the donut isn't long for this world. mike

[John H.]

Re: What is an "exhaust donut sleeve" used for?

The sleeve also reinforces the I.D. of the donut; the chamfers on the manifold surface and on the flange on the exhaust pipe squeeze the O.D. of the donut inward when the nuts are tightened, and without the sleeve, the donut will disintegrate in short order.

[Scott Marzahl]

exhaust donut sleeve

I have some old GM donuts in bags that are white in color, maybe even asbestos??
Are they any good to use compared to modern day materials.

[Chris H.]

Re: What is an "exhaust donut sleeve" used for?

When I first purchased my 396 in 2000, it kept blowing out the donuts and I couldn't figure out why. Then I learned about the "donuts".

It was quite exciting doing a full-throttle redline blast, and then have the donut blowout. You'd think a bomb went off.

[Patrick H.]

Re: exhaust donut sleeve

Buy the new ceramic ones. They work great and don't disintegrate. The part number should be in the archives, or maybe Joe L has it.

Patrick

[Mike M.]

Re: exhaust donut sleeve

didn't know about ceramic donuts but i've bought stainless steel donuts from local speed shop for years. they don't grenade. mike

[Brian Monticello]

Re: What is an "exhaust donut sleeve" used for?

A picture for the words:

[Patrick H.]

Re: exhaust donut sleeve

I think the ceramic ones are originally intended for recent build GM trucks. Joe L gave me the part number 2 years ago when I replaced my exhaust. They still appear as-new.

Patrick

[Wayne M.]

For some unknown reason, the sleeve was ...

not part of sidepipe assemblies, as delivered or OTC. All regular front (under) exhaust pipes I've seen have the sleeve integral (crimped or tack-welded) to the pipe in the exhaust manifold flange area. This is why we see sleeves show up ONLY on the AIM N14 sheet.

The real question is why the sleeves were not part of the sidepipe assy.

[Joe L.]

Re: exhaust donut sleeve

Patrick-----

Are you talking about the sintered iron rings? I don't recall any of ceramic material. There may be some but, if there are, I've forgotten about them.

[Patrick H.]

Re: exhaust donut sleeve

Yes, you're correct. I see you posted the numbers above.

Patrick