Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Id on Ul intake nipples

Id on Ul intake nipples

Post Wed Sep 09, 2009 4:02 am

Posts: 32
What is the id on Ul intake nipples?
I have serched this forum and the net but cant find any information on it.

Post Wed Sep 09, 2009 9:13 am

Posts: 369
Location: Bergen, Norway
1,303 inch
Dont think the one I have are OEM, but I don't remember.

Post Thu Sep 10, 2009 3:55 am

Posts: 32
not bigger than that, thought that they where alot bigger than wl.
Do you know what size the ul manifold has?

Post Thu Sep 10, 2009 11:52 am

Posts: 369
Location: Bergen, Norway
Sorry cant help you have no U Y-intake.

Post Thu Sep 10, 2009 5:31 pm
don User avatar

Posts: 575
Location: Spokane WA USA
I got 1.337" I.D. on both short and long manifolds, a couple that have been polished, 1.375" all the way to 1.430".
My N.O.S. nipples tagged 1112-37 & 27039=37 are 1.309" I.D.
I would taper the I.D. of the nipples to match the I.D. of the manifold, For smooth transition,
A Maximum of .250" into nipple at manifold nut thread I.D..
The manifold nut thread is .335" deep/long with a relief of 1.430" O.D.,
Then you have the threads that enter the cylinder.

Post Sun Sep 13, 2009 5:58 am

Posts: 32
okey, thanks for the info
Decided to take up the wl nipples to 32mm instead of the trouble with machining.
But as im going to use stroker plates under the cylinders i have to make a new intake manifold.
Does anybody know the outside diameter of the original intake, want to make one that i can use the original intake nuts with?

Post Thu Sep 17, 2009 2:11 pm

Posts: 369
Location: Bergen, Norway
Found my notes for the last WL Y-intake I opened up:
Id: 33.0mm/1.299 inch
Od: 36.1mm/1.421inch, this is the spigot cut for the PEEK seals
Throat 35.2mm/1.386inch. Have installed a 36 Mikuni VM on this bike.
Did braze to add to the thickness just for safety, although I never cut into it from the inside.

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