1940 and up intake nipple

[Jerry Wieland]

Who makes a good intake nipple for a big port knucklehead. Part number 27039-40. I need a pair of them.

Jerry

[Will]

Not sure if this is what you mean
I replaced the nipples in the head. I got Carl Olsen ( http://www.carlscyclesupply.com/ ) longer ones that had to be fitted to the heads. Turned out to be quite a job to get the old one out and clean up the threads, had to pless a friend and he made a special tool. But all in all these and Cotton peek mainfold seals were just the ticket. Both spark plugs burning at the same color
Hope this helps
W

[duffeycycles]

Jerry,Did that job last year,The colony[vtwin]are very loose threads-I reordered from Carl,Carl's aren't much better-very loose-I had an NOS to compare and it was snug
I was pissed the quality was so poor
Roger

[Steve Little]

Hey Roger.
If you still have the NOS unit, can you measure the major diam of the NOS thread and the aftermarket threads and post the readings here?
Regards Steve

[duffeycycles]

Steve,The only repro that I have came out of the motor,longer than original-They leaked bad-supposedly recently built by the best Harley mechanic in Texas!!![less than 500 miles] 1.740 thread od the original is 1.747
The original has rounded edge to the thread and the repop are very pointy-much deeper cut
If you hold them to each other and look into the light you can see lots of light because the repop is cut so deep,so it is more than the OD of the threads that are wrong
[or my original is an oversize that fit nice!]
You could help the Knuck world if you made better inserts
http://www.caimag.com/forum/showthre...ad+intake+leak

[T. Cotten]

Roger!

Please do not forget that it is not the threads that seal, but where the shoulder butts up against the thin lip on the head casting. If that lip is damaged, it can be quite an issue.
I have used nipples from several sources, but nearly always had to shorten the threads with the lathe. The only problem nipples I just couldn't use were Colony's with too large of a champher on the ID where the manifold ferrule seals.

....Cotten

[duffeycycles]

I agree, the colony I ordered got sent back.The threads are not the seal but they are important.
Loose crappy cut threads like the ones on an India made Royal Enfield fall apart.
The rivet quality is also an issue.The Colony rivets are too hard

[T. Cotten]

Roger!

The Colony rivets are not too hard for a simple hammer-smack, but far, FAR too fat!

Since no two holes will be the same, rivets must be cut individually to fit a reamed-to-clean hole, and with a tapered head as I described at http://virtualindian.org/11techleaktest.html.

How on Earth anyone expects a flat-headed rivet to seal upon a round ID is beyond me, but the H-D and Indian factories probably depended upon dedicated tooling with monstrous press pressure.

....Cotten

[duffeycycles]

I was told by a couple old Knuck builders that the Colony rivets were much harder than the originals and that combined with the smack method caused many heads with broken rivet holes,as the one I was doing had-I was told not to use them

[T. Cotten]

Roger!

The bottom line is that the Colony rivets should be avoided entirely, for a variety of reasons.

Their O-ring nipple seals are another example.

...Cotten

[bikerdds]

It is further recommended, especially if the lip is damaged to use JB weld or something similar to help seal the threads. Otherwise, some expensive welding is in the cards to restore the lip. Tom's suggestion for an anvil worked great when recently doing the nipples and manifold on my 39 knuck. Used nipples from Carl Olsen- were a good fit. Peek seals from Tom Cotton are the key to no leaks when installing the manifold on plumbers nut style carbs like an M-5. Used rivets from Old Dude, and since the holes on my 39 weren't damaged they fit fine and flattened out well. A little JB weld on them also is a help.

[duffeycycles]

None of the knuck owners I have talked to want JB weld on the threads-I used steam fitters pipe dope that I dried till it thickened before pushing it into the threads-The more info like Tom shares the better,he is a master of intake sealing and experimenting!

[T. Cotten]

Roger!

I have had excellent results with JBWeld over the years.
It survived my immersion tests in fuel quite well, although it should be cured a few weeks. I hear now there is a "marine grade".

S&S is using Permatex's "The Right Stuff" for the threads, and it miraculously survived my immersion test as well.

If the lip is damaged, I suggest silver-solder and skillful sculpting.
The lip ordinarily seals far better than the Panhead design!

....Cotten