48 pan threaded intake spigot replacement information needed

[MarkLindyHugo]

Hello all,
I have a 1948 panhead with under 25k original miles.
I am in the process of waking it up after a 20+ year slumber.
When last run, it was thought to have an intake leak. Bubble testing confirmed a very minor leak on the front spigot past the head threads
The rear spigot was more of a mystery. When I removed the intake manifold, I noticed the rear spigot was able to rotate a few degrees.
Closer inspection showed that the rivet is able to move in and out about 1/8 inch.
There does not seem to be any slop in the threads trying to pull/push the spigot.
I have tried to review the other posts about this subject in this forum and others, and I still have some questions I need answers to.
My service manual does not address this repair.

Assumption - the rear spigot needs to be replaced.

• Are the V-Twin spigots and rivets the right source or is there a better one?
• Is a thread sealant recommended when installing - if so, which one?

I plan on using green and draw a vacuum to seal up the leak on the front.

• Is there a torque spec for installing the spigot? How tight?
• Is the hole for the rivet drilled once the spigot is tightened in place?
• Is any sealant used when installing and peening the rivet?
• Is the rivet peened cold or heated?
• Can this repair be done with the head on the motor and the motor in the frame?

In conversation with other club members, I have been pointed to making an anvil from a bolt and coupling nut profiled to match the inside face of the spigot.
Is there any issue with this style of anvil?
Any other recommendations?

My dad owned this bike from new, and I have all the receipts. The heads have never been off. It almost 'looks' like it was never fully peened at the factory, but that seems unbelievable.

As always, I appreciate the thoughts and advice here.
Thanks
Mark

[PaulCDF]

48 pan threaded intake spigot replacement information needed



Mark;

Here is a link to a previous discussion on topic:

Chief nipple removal tool - AMCA Forum

NOW the thing of it is IN THAT DISCUSSION is a Link Tom Cotton provided to Virtual Indian 2002 (Why that link is still working I don't know but the article is PURE GOLD)
Discusses manifold leak testing AND nipple rivets.

There are many other post on forum on point as well IMO the above is the best.
In the search box just use keyword "nipple"

Good luck. Please keep us posted.

[dukekleman]

Hello all,
I have a 1948 panhead with under 25k original miles.
I am in the process of waking it up after a 20+ year slumber.
When last run, it was thought to have an intake leak. Bubble testing confirmed a very minor leak on the front spigot past the head threads
The rear spigot was more of a mystery. When I removed the intake manifold, I noticed the rear spigot was able to rotate a few degrees.
Closer inspection showed that the rivet is able to move in and out about 1/8 inch.
There does not seem to be any slop in the threads trying to pull/push the spigot.
I have tried to review the other posts about this subject in this forum and others, and I still have some questions I need answers to.
My service manual does not address this repair.

Assumption - the rear spigot needs to be replaced.

• Are the V-Twin spigots and rivets the right source or is there a better one?
• Is a thread sealant recommended when installing - if so, which one?

I plan on using green and draw a vacuum to seal up the leak on the front.

• Is there a torque spec for installing the spigot? How tight?
• Is the hole for the rivet drilled once the spigot is tightened in place?
• Is any sealant used when installing and peening the rivet?
• Is the rivet peened cold or heated?
• Can this repair be done with the head on the motor and the motor in the frame?

In conversation with other club members, I have been pointed to making an anvil from a bolt and coupling nut profiled to match the inside face of the spigot.
Is there any issue with this style of anvil?
Any other recommendations?

My dad owned this bike from new, and I have all the receipts. The heads have never been off. It almost 'looks' like it was never fully peened at the factory, but that seems unbelievable.

As always, I appreciate the thoughts and advice here.
Thanks
Mark

Mark,

I typically use Colony spigots, however on occasion, I find myself making a custom spigot.

I torque the spigot on aluminum cylinder heads to 40 Ft lbs.
Keep in mind this torque value is NOT a dry torque. It is a lubricated torque as I use Loctite 565 thread sealant on the threaded portion.
After torquing the insert, I then drill the assembly in place for a proper rivet fitment.
I have special tooling I designed/adapted and built for cold pressing the rivet. My tooling allows me to perform this entire process on the motorcycle, fuel tanks installed.
I allow a full cure of 24 hours for good measure and long success.

I hope this helps,

Duke Kleman

[MarkLindyHugo]

Thanks for the link to the Indian write-up by Cotton. I had not seen that in my previous searches.
Mark

[otis71]

Personally I forgo the thread sealant because the nipple is straight thread and not tapered. I do use JB Weld where the nipple meets the head. Often the rivet hole is wallowed out and an oversized rivet is needed. I redrill the hole the least amount necessary to make it round and then turn a rivet to have a slight interference to the hole. Softening the rivet with heat and slow cooling helps too.

[marksg]

Mark,

I typically use Colony spigots, however on occasion, I find myself making a custom spigot.

I torque the spigot on aluminum cylinder heads to 40 Ft lbs.
Keep in mind this torque value is NOT a dry torque. It is a lubricated torque as I use Loctite 565 thread sealant on the threaded portion.
After torquing the insert, I then drill the assembly in place for a proper rivet fitment.
I have special tooling I designed/adapted and built for cold pressing the rivet. My tooling allows me to perform this entire process on the motorcycle, fuel tanks installed.
I allow a full cure of 24 hours for good measure and long success.

I hope this helps,

Duke Kleman

Any chance you would want to share a picture of your tooling. I enjoy the process of learning and doing for myself.
Cotten shared a picture of his Linkert throttle disk arbor and I had to go out and by a lathe.
It is great when those with knowledge pass it down to those of us learning. I appreciate this forum.

[joe fxs fxr]

Cotten shared a picture of his Linkert throttle disk arbor and I had to go out and by a lathe..

Classic!!!
Keep up the good work

[T. Cotten]

Again for reference, Folks,..

https://web.archive.org/web/20250615...hleaktest.html

Please note that was a quarter-century ago, and the question of a sealer is still up for grabs.
'Seal-Lock' has its limits; 'J-BWeld' can be successful, but it needs extended cure to resist fuels.
Beware of any 'Loctite' that tastes like saccharine, as it will wash out.
(We desire a sealer of course, even if it is 'suspenders and a belt'; Since the Factory achieved a seal without one, we must question if so many of the fuel-digestible goobers reported to succeed wouldn't have achieved a seal without them.)

Please also note that the sealing surfaces for Pan nipples are painfully wide, with nothing to bite into each other for a mechanical seal, even though the Factory apparently never used a sealer (as Indian did). Both the face of the nipple and seating face upon the head must be dressed of all blemishes.
(Parkerizing on nipples can also interfere with sealers, particularly 'Seal-Lock'.)

The greatest problem with Pan nipples is that the heads were often stripped out by callous disassembly.

....Cotten

[joe fxs fxr]

The best gas resistant sealer I've found is EZ-Turn aircraft sealer.

ezturnlube.jpg

[dukekleman]

Any chance you would want to share a picture of your tooling. I enjoy the process of learning and doing for myself.
Cotten shared a picture of his Linkert throttle disk arbor and I had to go out and by a lathe.
It is great when those with knowledge pass it down to those of us learning. I appreciate this forum.

Here's an image of the components and the tools I use to repair failed inserts.
IMG_20260407_173536940.jpg
I saw a few others comment on sealer or no sealer that others have used...
Does anyone else in the AMCA community have torque values to share they've had success with over the years?

Or tooling photos to do the actual repair on or off the engine? I really enjoy learning...

I know he was looking for options on this criteria.

Hope this helps,

Duke Kleman

[T. Cotten]

The best gas resistant sealer I've found is EZ-Turn aircraft sealer.

Does it stay fluid to be a lube, Joe?

Or does it set up'?

If it doesn't, the pulsing vacuum sucks it out.

...Cotten

[joe fxs fxr]

Does it stay fluid to be a lube, Joe?

Or does it set up'?

If it doesn't, the pulsing vacuum sucks it out.

...Cotten

It's a thick and sticky gel, and it doesn't harden.

[Omarttentmaker]

My knuckle needed spigot replacement about 40 years ago, and at the time, I wasn't enlightened enough to look for or make a back-up piece to put in the opening to act as an anvil after installing a rivet. Here's what I did. After installing new spigots, I drilled and tapped the rivet hole ( I think for 12-24 threads). Then I coated the screw threads with some kind of sealant. I screwed in 12-24 filister head screws and gave the sealant time to set. After testing to make sure I had a seal, I took a Dremel and dressed off the heads of the screws to remove the screwdriver slots. it's been like that ever since.

[Architect]

Last one I did, we spent a very long time cleaning all the threads on my cylinder until the nipple spun in, by hand, until fully seated. Per Cotten many years ago I used JB Weld. It is for sure a PITA job, good luck.

[T. Cotten]

It's a thick and sticky gel, and it doesn't harden.

Then you better get a good mechanical seal, Joe,

(Non-hardening 'Hylomar' can suck out as soon as the motor starts!)

There are two places where the factories achieved a mechanical seal: Where the nipple butts against the head, and at the rivet.
The threads are not self-sealing, as they are not interference tapered like pipe threads, thus any goober is inevitably exposed to fuel.

Rivets were sealed by their expansion in their bore when "upset", or peened. (Threading the bores not only creates a channel for leakage, it introduces stress-risers into the casting, and enlarges the bore, making future repairs even more difficult for posterity.)
As noted in the VirtualIndian discussion, a tapered head upon the rivet can achieve a mechanical seal upon the inside of the nipple, as well as a bore seal if the hole is reamed clean, and the shank cut to fit.
(Heat is used only to anneal the rivet before installation; Large nails can be cooked cherry red in coals, and allowed to cool slowly before lathe-cutting as needed.)

As everyone who has cut valves and seats knows, the wider the mating faces, the harder it is for them to seal, so the butt of the nipple against the head is particularly troublesome.
(Knucks at least had a thin lip of the head to bite into the nipple.)

....Cotten