PAN CYLINDER BASE NUT QUESTION

[BCOWANWHEELS]

Can somebody tell me if panhead engines and shovel head engines take the same size cylinder base nuts ?
thanks
bob

[RUBONE]

Yes, they do!
Robbie

[Cotten]

Except for those 80" Shovels that had short nuts and triangular blanchards.
They work fine, maybe better, but there will be threads exposed.

....Cotten

[Bosheff]

1978 74" shovels used the later style nuts and triangulars also....bosheff

[RUBONE]

True, but his question was size, not style, so even the late ones are the same size, 7/16-20.
Robbie

[Cotten]

But Robbie,

Shorter is a different size.

The triangular blanchards were a good thing. I think I have them on a Knuckle.
I'll have to look and see how bad the threads show.

....Cotten

[Cotten]

A correction:

It appears that the shorter nuts will not expose threads if used with the triangular blanchards, even on early OHV cylinders. (Warning: Purists will blanche at this photo of one of my '37s, built in the '80s)

TRIBLNCH.jpg

....Cotten

[George Greer]

Cotten.

Question, and I think that I already know the answer.

The triangular blanchards, are they are used to evenly distribute the torque/clamping on the cylinder?

George

[Cotten]

George!

Absolutely.
When bored well into their life, H-D's enormous spigots distort dramatically from fastener stress, both inward and outward, and outward on the cylinderwall above each cylinder base nut.
The large blanchards spread the stress, reducing overall distortion.

Metal moves.

I had incorrectly guessed at their introduction with 80" Chubbles, because those cylinders were basically a .060" over-bored 74", which is the point where torque-plates begin to show noticeable effect.
I thought they thickened the base flange at some point as well.

My Knuck in the previous post is .115" over-stock, if a failing memory serves.
(Hope to get it back into a frame some day!)

....Cotten

[Panhead Ed]

why worry about the opinion of purist on the blanchards? seems to me the exhaust spigots are more noticable ..

[Cotten]

Panhead Ed!

That's to distract the eye from the auto-advance circuitbreaker.

....Cotten
PS: That is only a knock-in insert, for Pan pipes that are more forgiving. Plus a minor reversion dam.