The Stovebolt Site Forums The Shop Area Engine Shop 216 exhaust questions

I am amazed at how little there is available on this topic. My most basic question is this: How was the exhaust pipe to manifold transition done originally? My research says that to begin with, the pipe is 1 7/8" in diameter. However, most after market stuff seems to be 2". So right away, we have an issue. Second, there are two types of gaskets. One is flat and in the shape of the two hole flange. The other, and I understand the correct one, is a "donut". What no one has been able to tell me is if one uses a donut as I understand was original (and hard to get) do you have to flare the end of the pipe? The replies I get talk around the question but don't answer it. How, in fact is this union done? Straight pipe, donut around pipe, whole shebang held in place by flange no flare required? Pipe flared, donut in pipe and then mated to manifold all held in place by flange? Pipe flared, donut around pipe pipe flare held in manifold and gasketed by donut held in place by flange? Anyone have the REAL answer?

Thanks,
Roy

Roy,

First, let's quickly dispel the thought that the donut gasket is hard to get.

Part Number: FPG 8592 (NAPA, Advance Auto, etc)
Product Line: FEL-PRO Gaskets

Do you have a 216 exhaust manifold? If so, it has a recess in it for the donut. The proper exhaust pipe would have a collar that would pull the flared exhaust-pipe end towards the manifold (with the donut between the exhaust pipe (inside the flared-end) and the manifold).

I believe that early 216's had a 1 7/8" pipe, but before about 1950 they used 2" pipe, swaged to 1 7/8" at the manifold.

Also, the flat gasket and welded flange was adopted in 1950 on 1/2 - 2 1/2 ton trucks.

So says my Canadian 48-50 Supplement manual, things in the US might be different, just like things in real life are different from the manual sometimes.

I put my exhaust back together on my chevy 52, 3100 with the 216. Everything I observed with my exhaust concurs with the comments above by "tclederman." I got the donut gasket through classic truck parts, but you can obtain it through napa auto parts as well. Additionally my exhaust pipe does have the flange welded too it. The pipe itself is not flared. The donut sits over the pipe. The manifold has a "bevel" in it..(for lack of a better term) to accept the donut. 2 bolts mate the two together.(don't forget a little anti-seize)

Thanks, guys. This helps even though tclederman says "collar around the pipe, donut inside it, Danhami says flange welded on the pipe, donut around pipe, and Mr. Lang says flat gasket and welded flange. I am sure any would work. My truck is a '51 with a 216 manifold. The welded flange and flat gasket seems like it would be easiest to DIY and Mr. Lang's book seems to suggest that there is more than one "right way" depending on the year. I plan to use 1 7/8" stainless. Danhami, I don't suppose you remember how much of that pipe was sticking out of the flange, do you?

Thanks,
Roy

It was maybe sticking out an inch roughly....you need pictures? I could take it apart if you do....I cannot guarantee that it's original though. My knowledge of exhaust systems on these is minimal.

Here is the flange off my 216 exhaust
...pic...

...pic...


Local Auto Parts Store had the donut gasket.

If that "collar" on the end of the exhaust pipe is welded on, the donut might work if everything lines up properly.

The original style exhaust pipe had a loose collar (I think) and a flared end, into which the donut would seat itself upon tightening.

Once again, guys, thanks a lot! This has really been helpful - pics really great, too. Looks like Dads50's is the same as Danhami's in that it is a straight pipe with a welded flange and a donut on the outside of the pipe. As I said from the beginning, it is amazing how many "correct" ways there are to do things on these old trucks. I have heard as many "donuts inside the flared end" as I have "donut slid over the pipe" and, of course, lots of discussions around flat gaskets. If I were to speculate, I would say that the donut is supposed to go in the flared end but works just as well, if not better, than a flat gasket and I bet the donut around the pipe has been a common replacement for the flat gasket. Now I have to decide whether I weld a 1 7/8" mild steel flange or a 2" stainless one on my stainless tubing. I think the 2" will work just fine if the bolt holes work.

Roy

Yep! Those pictures are exactly what I have too.