Topic: Problems installing stock 4-1 exahust on 1976 750A...

[j2dawson]

The stock pipes on my 750A were in terrible shape so I bought a good used set. When trying to install the pipes I found two references that show the split collars going in with the flared end toward the heads and two sources showing it going in with the flares toward the front wheel. I first tried it with it pointing toward the wheel and it leaked like crazy. when I removed it, the new crush washers were not even touched, much less crushed. I turned them around and tried it with the flares toward the heads and the studs aren't long enough to start the nut, either with or without the crush washers installed.

When I removed the original pipes I remember the flares being toward the heads.

What the heck am I doing wrong?

Thanks for any help,
Jim

[dave the welder]

did you remove the old crush washers???

[j2dawson]

did you remove the old crush washers???

If there are old crush washer there I can't see them or they are so fused to the heads that I can't get them out.

I misspoke in my post, I first tried it with the flares toward the heads with new crush washers and everything seemed to torque fine but they leaked like crazy. When I removed them the crush washers they weren't even touched, like they weren't even been contacted by the collars. I reinstalled the collars with the flares towards the front and WITH or WITHOUT
the crush washers there isn't enough stud showing to get a nut started. It's like either the collars are too long or the studs are too short.

Can someone tell me which way the split collars should be installed?

I'm about to sacrifice the old headers and cut one end off so I can try to bolt it on and figure out how it should go on.

[stikman]

Check out this thread, might help:  http://forums.sohc4.net/index.php/topic,148431.msg1691637.html#msg1691637

You shouldn't need to cut up your other exhaust.  Just be patient and the guys here will be happy to walk you through it.  If you're still having trouble after going through that thread, maybe post up a few pics for us.

The split collars are installed with the flared lip facing away from the head and the thin end facing toward the head.  From what I understand there are a few different collar lengths depending on year and/or aftermarket collars, but if you're using the ones that were previously used with that same head then you should be fine.  I have heard of some having to double up those copper gaskets if they can't get a proper crush.  Hope that helps some.  Keep us posted.

[j2dawson]

Maybe I do have the wrong length collars. They were installed backwards when I took it apart originally and now when I try to install them correctly they reach the surface of the head before there are enough threads exposed to start the nuts.

I don't know how they were sealing while installed backwards since when I try that way they don't crush the washers and leak like a sieve.

I was going to cut an end off the old one so I could keep trying without having to hold the whole mess up there but that would be a waste.

[j2dawson]

The other thread referenced indicated that there are two different length collars, roughly 1" and 1 1/4" long. Mine measure 1.395" long. I think they are the wrong ones and that's why, at some point, they were installed backwards.

I wish I had a couple shorter ones to test my theory.

[stikman]

Also, I understand the early heads have a different depth of hole into the head for the exhaust pipe.  If you have vernier calipers you could measure the hole depth from the surface the copper washer sits against to the surface the studs are screwed into, and compare that with the length of the assembly with the split collars, heat sink clamp, and copper gasket held together in order on the end of the pipe.

[j2dawson]

Also, I understand the early heads have a different depth of hole into the head for the exhaust pipe.  If you have vernier calipers you could measure the hole depth from the surface the copper washer sits against to the surface the studs are screwed into, and compare that with the length of the assembly with the split collars, heat sink clamp, and copper gasket held together in order on the end of the pipe.

Good idea, I'll do that now.
Thanks

[j2dawson]

Thanks everyone for their help - I finally got it on! It turns out that it just took a lot of "persuasion" with a big mallet and two people twisting on things to get it lined up. I had to mount the muffler so I would have some leverage to twist things around.

Now the only exhaust leak is from the joint between the muffler and header. I'm trying to find a solution other than the $45 gasket on Ebay. I read somewhere about some type of tape that could be wound around the pipe as a substitute for the gasket but I can't find the thread. If anyone knows what I'm talking about, please let me know.

Thanks,
Jim

[stikman]

Right on, glad to hear you got it worked out without wrecking your other pipes.  I'm not familiar with the pipe tape you're talking about, but I would assume a little red rtv would do the trick for cheap.

[j2dawson]

Right on, glad to hear you got it worked out without wrecking your other pipes.  I'm not familiar with the pipe tape you're talking about, but I would assume a little red rtv would do the trick for cheap.

That would also be the easiest, I'll try that first.