45 Intake Nipple Loose

[Rex]

The front cylinder intake nipple is loose on my 45. The rivet is solid in the cylinder, but the nipple rotates @ 1/32" in both directions. Very bad air leak. Should I drill out the rivet and buy a new nipple?
I remember seeing in a forum somewhere that someone replaced the nipples in a 45 with ones from a UL and didn't use rivets. How does that work?

[Paps]

No doubt you will need to remove it. Inspect the hole diameter and check to see if resizing will work. You can fit an over sized rivet to it if the hole will allow resizing. Paps

[Rex]

Paps-
Replacement procedure in progress.
Thanks for the advice.

Rex

[Paps]

Great !! Keep us posted on your progress. Paps

[Rex]

Intake Progress Report

Paps-
2 new intake nipples and rivets installed. PEEK seals doing their thing, but still couldn't stop the bubbles on the rear cylinder.

Upon closer inspection with very low air pressure and just water, I found the leak is from the nipple/cylinder junction.

The threads in the cylinder were shorter than the threads on the nipple, and I had to shorten the nipple to get it to go in far enough to mate up to the cylinder.

The cylinder thread also seemed to be a bit shallower than the one in the front cylinder.

Tomorrow I will replace the pressure test setup with a small vacuum pump. I will apply Fluid Weld sealant to the leaking area while it's under vacuum so it will be drawn into the leaking area.

[Paps]

Bummer..........At least you got the main leak targeted. Those threads can be a stinker sometimes. I had a fella unearth an nos oem cylinder recently from factory cosmoline and what he found was disturbing. The installed nipple threads were totally corroded away. I found him an nos replacement nipple and he was successful in removing and installing it. He was able to use a standard size rivet also. Thread sealers are a diverse issue. Many folks recommend one type while others recommend others. Shortening the threads may cause another issue to arrise. Angle of intake ??

What's your take on the sealers and thread shortening Cotton,.....others ? Paps

[Rex]

Cylinder Intake Threads

Bummer indeed.
Yes, shortening the thread that screws into the cylinder was all I could do to get the nipple to seat on the cylinder spigot face.

The front nipple went all the way in, but the rear one stopped @ .250" away from mating to the spigot.

I found where the conflict was by coating the inside of the spigot with blue layout fluid before test fitting the nipple. The crash point was where the cylinder threads stopped. I slowly ground the nipple until it spun all the way into the cylinder. I also used the fluid on the spigot face to know when the two surfaces mated. Love that fluid.

Seal Lock Fluid-Weld was used on the rivets and nipples.

The rivets were made of annealed hot rolled steel, with a bevelled head. They were driven with a hammer, punch and cam ground slug.

I know there isn't a perfect sealant for this application due to the hostile nature of the fuel, but I'm stuck with using whatever is available at this time.

Since the manifold is under vacuum, I think that most of the errosion caused by fuel will be at the bottom of all the junctions during priming or flooding when starting.

I have a small laboratory vacuum pump and a Magnehelic differential pressure guage to help determine if the sealing attemps are effective. The vacuum indication should change as the leaks are filled.

From what I've seen so far, I don't know if I can ever get to a "Zero Bubbles" pressure test condition. If I do, I'm not sure it would last very long.

If someone were to take a pressure test setup to a meet and test 100 bikes with this manifold design, how many would pass?

[Rex]

Intake Sealing Progress Report

Success!

Using the vacuum method worked. I did a pressure test today after @ 50 miles and several heat/cool cycles and scored 0 bubbles.

I'm following up on a possibly better sealant from the aircraft industry and will share what I find.

Rex

[T. Cotten]

Colony nipples often must be shortened, and I consider that a good thing.

Rex has proven the unusual perseverence and patience necessary to overcome EVL (Evil Vacuum Leak).

....Cotten