Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Exhaust Manifold Bolts

There has to be a gasket or you would have had an awful racket coming from the pipe to head interface. The stock gasket is a graphite impregnated stainless steel mesh that is not all that apparent when the pipe is removed as it would be very compressed at this point. Use a right angle pick to clean out the pipe seating area in the head (which should be a right angle machined pocket-no taper) and I believe you will find the stock gasket is still there.

I'm not sure why Morgan used the spacer. Perhaps to avoid over crushing the mesh gasket? The first time I removed my pipe for polishing I left off the spacer and using the James ring type gaskets I had no issues at all.

Many thanks, you are 100% correct. I was able to remove the gasket which I didn’t notice at all, it really blended in well with the engine.

What is the torque spec for the studs and nuts?

Did you use Loctite on studs?

Torque spec is "tight enough to seal without bending the exhaust flange". Retighten after the first run and they will stay tight thereafter.

Seriously, getting a torque wrench on the exhaust nuts would be pretty difficult, though not impossible with a long extension. I believe it's more important to get the two nuts evenly loaded so the exhaust gasket is seeing approximately even pressure all around.

I use loctite red 271 on the stud to head threads and none with the self locking jet nuts (because they really don't need any). In fact I use a tiny amount of anti seize on mine, and they do not loosen.

I should also note I replaced the bent stock exhaust flanges on my M3W with nicely machined (and straight) Harley units. If your flanges have been bent by an overzealous mechanic it may be difficult to get a reliable seal.

If I didn't mention this before, If you are going to use jet nuts, buy actual mil spec units from a reputable source like Pegasus or Aircraft Spruce. Good enough for actual aircraft is good enough for my Morgan.

I ordered the ARP studs and the jet nuts. Looking at the picture of the studs I assumed that the end round was in a hex shape for driving in. It is only a very smooth round that was quite easy to lock onto and drive in until it seated. I used the Loctite 272 for those. The jet nuts were ordered from Pegasus and were a snap to tighten using a 3/8" socket! What a difference that made! I also used the down time to replace the front tires for a new 7th pair! My third pair of Coker Excelsior Comp H. So far they have outperformed the Blockleys and I won't even go into the Avon debacle.

I am glad I started this thread in that I learned some new tricks that will become very useful. This forum has saved my sorry ass so many times...

Thanks to all!

And thanks for this Thread, I have learned a lot as well👍

Just received my ARP studs and the coarse side is about 1/4 inch shorter than the stock one. Is it OK?

It should be just fine. Besides the Morgan, I've used the ARP studs on two different Lotus Elan, and a Jaguar E-Type, all with alloy heads.

In my experience the head side stud threads on the Morgan were unusually long. Might have been the S&S specification or just that Morgan used longer thread studs.

Is there a reason to NOT use S&S studs?

No-other than they rust, not being stainless steel. At least the ones that came out of my heads were not stainless.

Or in other words, if you are not removing the exhaust for some reason, and/or don't care about rusty studs, there is no reason to replace them.

In any case, the reduced hex jet nuts are worthwhile as they make it so much easier to remove/install the exhaust.