Confirm use of Exhaust Extension with heat Riser on 1973 SB

[David C.]

Hi all,
I am addressing a RH side exhaust leak at the junction between the exhaust pipe and heat riser on my 1973 L82. Now the AIM shows the use of an extension between pipe and heat riser which the packing donut fits around, and this extension is indicated on both the RH side as well as the LH side (between pipe and exhaust manifold). However, when I disassembled the RH side today, there was only a deteriorated donut -- but no extension. Also, the various parts house diagrams show only an extension on the LH side, not the RH side with the heat riser.
I have searched the archives, but want to be sure -- should there be a 2" extension (with donut) on the RH side?

One related question, I have loosened/removed the center cross member exhaust hanger and still cannot get enough up/down movement of the exhaust pipe to clear and remove the heat riser from the manifold studs (idea is to also replace the heat riser to manifold gasket while I am doing all of this). It appears I will have to remove the rear exhaust hanger and drop the muffler so that I can get more fore/aft movement to move the exhaust pipe back out of the way and then drop the heat riser off of the manifold studs. Any other ideas (looking for "easy" of course!)?

Still learning....

Thanks.
Dave

[Joe L.]

Re: Confirm use of Exhaust Extension with heat Riser on 1973 SB

Hi all,
I am addressing a RH side exhaust leak at the junction between the exhaust pipe and heat riser on my 1973 L82. Now the AIM shows the use of an extension between pipe and heat riser which the packing donut fits around, and this extension is indicated on both the RH side as well as the LH side (between pipe and exhaust manifold). However, when I disassembled the RH side today, there was only a deteriorated donut -- but no extension. Also, the various parts house diagrams show only an extension on the LH side, not the RH side with the heat riser.
I have searched the archives, but want to be sure -- should there be a 2" extension (with donut) on the RH side?

One related question, I have loosened/removed the center cross member exhaust hanger and still cannot get enough up/down movement of the exhaust pipe to clear and remove the heat riser from the manifold studs (idea is to also replace the heat riser to manifold gasket while I am doing all of this). It appears I will have to remove the rear exhaust hanger and drop the muffler so that I can get more fore/aft movement to move the exhaust pipe back out of the way and then drop the heat riser off of the manifold studs. Any other ideas (looking for "easy" of course!)?

Still learning....

Thanks.
Dave

Dave------


The extensions were used on BOTH sides. If your right side does not have one, that means someone left it out in the past. The junction between the heat riser and the exhaust pipe is exactly the same as the junction between the exhaust pipe and the manifold on the left side. If, per chance, the extension is too "tall" and it extends up into the heat riser valve and interferes with the flapper, simply trim off the excess. The extension does not need to extend above the donut gasket.

As far as your exhaust pipe removal problem is concerned, you have other options. One is to remove the exhaust manifold studs. For all practical purposes, this is not really an option since the studs can be EXTREMELY difficult to remove (if you can remove them, replace with stainless steel). The other option is to just remove the manifold. It's really not all that hard to do this unless the car has A/C.

[Richard M.]

Re: Confirm use of Exhaust Extension with heat Riser on 1973 SB

I agree.....

I would stay clear of trying to remove the long studs on a 42 year old manifold. The manifold to block attach bolts are Grade 8 and should come off much easier with less risk of damage.

[David C.]

Re: Confirm use of Exhaust Extension with heat Riser on 1973 SB

Thank you for the advice Joe, and Richard.