Intake nipples

[Bill Pedalino]

I'm installing new manifold nipples in my '53 panhead (and in ,y '47 knuckle). Does anybody have a suggestion as to whether or not a sealer should be used on the threads or not ???

have installed them dry in the past, but now want extra insurnace against intake leaks.

Thanks !

[T. Cotten]

Historically, I have found positive evidence of sealer upon Indians, but nothing definite upon Harleys.

Obviously this difficult procedure needs every advantage possible. The best that I have found (so far) is "Fluid-Weld" from
http://silver-seal.com/
The parkerizing must be removed from new nipples, and of course the threads in the head must be scrupulously clean as well, since the sealer forms a chemical bond.

The important thing is to pressuretest each step. More suggestions can be found at http://virtualindian.org/11techleaktest.html

Please note the rivet peening anvil, as it is of great importance. Ignore the wrench portion unless you are tempting fate by attempting to replace a nipple while the head is installed. It is much more sensible to hold the anvil in a vise while the head is twisted upon it.

Good luck, as nipple replacement is probably the most trying procedure in all of vintage motorcycle restoration.

....Cotten

[Bill Pedalino]

Cotten,

Thanks for the reply. I have replaced many an intake nipple over the years and you are correct - it can be a real pain, especially removint the old ones. Luckily these are in cast iron knuckle heads - I've found the pan heads to be more problematic. ANyway, the new nipples turn in quite nicely - but I will try the fluid-weld suggested by others.

As for the rivet anvil - I usually clamp mine in a vice and heat the rivet. This makes the peaning much easier and also allows a tighter grip when the installed rivet cools and contracts - just like the structural iron workers used to do it!

[Lonnie]

A friend of mine who has done a number of AMCA Senior-type restorations, Larry Gee, showed me a tool he uses that functions as an anvil when replacing the nipple and rivet while the head is on the engine and in the frame. I borrowed it and tried it myself on a panhead. It worked well and did not damage the head. The tool is made of a piece of cold-rolled iron bar, cut off to a reasonable length so it will fit one head while the other is on, then ground to fit on the end that goes into the head.

The risk of damage is in removing the old nipple and rivet. I stuffed a greased rag down in the intake and put grease on the end of the rag to catch any chips - there was no conceivable way that one would escape. The biggest problem would be where the original nipple is distorted from the original or replacement and stripping out the threads when removed. I was fortunate there, while others have not been so lucky.

It may not be the best way, but it worked here and in other instances.

Lonnie
Lonnie

[exeric]

The bigget problem I have found with replacing nipples in panheads is the burred rivet hole in the nipple wants cut and tear it's own threads as you run the nipple out of the head. Someone on this forum recommended cutting the nipple in sections to remove it which I think is the best advice I've heard. the last one I did was at least 15 years ago and the rivet hole did exactly as I described. I had to make an oversize tap to repair the head. I made the tap out of tool steel and it had to have a taper at the front to pick up the few good threads down in the head. I didn't bother to have the tap hardened becuase it was plenty hard enough to cut aluminum and it was a one-shot deal. In addition I had to make an oversized nipple to match the threads I cut in the head. I still have the motorcycle and the nipple in the rear head is loose so I'm going to be doing this again. Of coarse I didn't save the tap I made but maybe this time I can get the nipple out without doing a lot of damage to the head, but the key to all of this is a nipple that is well fitted and properly rivetted so it won't loosen up in the head.

[T. Cotten]

Since we seem to keep covering the same ground over and over,
let us please review the discussion at http://virtualindian.org/11techleaktest.html
The responses from that List were few, and I am certain that someone here has improved approaches to this difficult task.

Lonnie's anvil description is very much as I have pictured at that link. A cam-action gives the critical advantage of pressing the rivet outward. With a tapered head, the rivet is then self-sealing and requires only minimal peening to prevent it from loosening, and reducing the risk of splitting the casting. On Knucks, this also gives an original appearance.

PAC Machine and Carl's Cycle are most capable of offering oversized nipple service. I hope they will chime in!

Rivet distortions and loosening of nipples results from the tremendous torque needed to compress even an annealled brass ferrule. Shops worldwide are now custom-cutting the thermoplastic PEEK to eliminate this agony.

....Cotten