[Ccass]

here are pictures of a standard manifold downpipe installation. Notice how the flare is not even close to the studs. There should be no need to grind the pipe down on these downpipes. This manifold is fully seated and should not leak.



here are pictures of a HO/RA manifold downpipe installation. Notice how the flare is actually touching the studs. This can prevent the flare from seating properly if it can't expand upon tightening. The Left hand picture shows the grinded flare. There is a larger gap above the flare and on the sides. This manifold is fully seated and will not leak.

[Larry Navarro]

I have this same problem on the SD with the Pypes crossflow setup,
passenger side manifold/downpipe juncture.
I've been putting off checking the connection and would have never figured the flange on the downpipe would be the problem.
great info. pics definetly do help.

[Larry Navarro]

Kudo's to Chris for updating the design of pipe connections. I made a recommendation awhile back that small "slots" be cut lengthwise at the pipe openings where the u-bolts secure the pipes together. This inturn eliminates deformed and otherwise impossible separation of pipes after they are tightened.
I noticed this on Russels(69*goat) Pypes system he bought a couple of weeks ago.
This trick definetly eases the connection and disconnection of an exhaust assembly and the possibility of losing a system when leaving the wal-mart parking lot.

[Ron H]

I had no issues installing a 3" x-change system in my 68 firebird. It takes a bit of patience but is not difficult.

[Larry Navarro]

I "reshaped" the flare on the downpipe and no more leak.
Thanks for the tip Chris.

[hillpc]

I had the same bottoming out problem with one of the Pypes downpipes on my 66 GTO, with the same recommendation to grind the end of the pipe. And I also messed up the grinding operation. Then went to the local autoparts store and looked through their catalog and stock of exhaust donuts, ordered one where the OD was about right, and butchered the ID larger with a die grinder. Inserted it into the joint and it cured the leak. But now it sounds like it's starting to leak again, after about a year. I haven't looked at it to see what's changed. It'll be a lot easier now with the lift I just installed. I suppose I could have ground off just the right amount in the right spot to make it work, but I'd run out of patience with the original grinding modification because it was such a pain to take on and off lying on my back under the car.

[Ccass]

This week I looked at a 67 Firebird standard manifold installation and noticed that the passenger side manifold outlet hole was quite small. The flared downpipe was too big for the manifold. A donut type gasket is certainly a solution. With this particular Pypes installation, they solved the problem with the addition of a sleeve insert. Why an overwhelming amount of installations don't require this sleeve/donut addition and why apparently some do, is a mystery at this point. However, one thing that is very clear that has come out of this topic:

1. DO NOT grind the pipe flare down with standard manifolds when the pipe flare is bottoming on the manifold. Even a slight amount of grinding will cause the flange to be too big for the flare. The solution is the addition of a donut gasket or sleeve. Anyone who got this advice on a standard manifold got bad advice. Contact Pypes for replacements. Our appologies.

2. DO grind the pipe flare down with HO/RA manifolds if the flare is bottoming on the studs when tightening.

Pypes is working on making a sleeve that will be included with all Pontiac standard manifold downpipes.

[GTOWAGON]

Now thats great customer service.Well beyond what most aftermarket manufactuars will do

[hillpc]

Can you specify a make and part # of exhaust donut that will work here (on standard manifolds), for those of us who have already butchered up the pipes?

[Ccass]

Originally Posted by hillpc

Can you specify a make and part # of exhaust donut that will work here (on standard manifolds), for those of us who have already butchered up the pipes?

Pypes has not tested a donut gasket yet. I believe a customer above found one that worked. Pypes is developing a sleeve insert. It should be available in about 1 month.

[1coolfish]

They really do have some great product's.