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Is there a differance in the intake manafolds from a 61" and a 74" from head to head, a friend has a 47 knuckle 74" he just put it togeather and the intake is loose,tighten one side and theres a gap at the other,any info will help
 

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The gap between the head and manifold should be about 1\32" on either side.If you are using conversion nipples so that you can run the Oring manifold they are likely your problem.If you are using an aftermarket intake manifold it may well be too narrow.I have several in the shop and no two are the same.
 

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If the gap is minimal or if you have trouble getting your manifold to seal properly, it is a good practice to leave the cylinder base nuts a little loose while tightening the manifold nuts. Also, be sure to pressure test the manifold after it is installed. Air leaks can make it impossible to tune.
 

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And 1940 was the only year that was brass.
That is another urban myth. The '40 only manifold is steel and is unique in that it is four bolt but with a very short inlet length for the use of the standard 6 inch air filter still in use. None of those short manifolds have ever appeared in brass. The '41 and later manifold has an extended intake to allow use of the 7 inch air cleaner. The only brass manifolds appear on original unrestored '47 models.
And save your breath quoting Palmer's book. He is aware of the inaccuracy of that description but the publisher won't correct it along with the hundreds of other corrections he would like to make! Although it is still the best guide out there!
Robbie
 

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No bullshit.. I own a 40 el.. Itz brass.. The end!
Certainly not the end! How about a close up picture of the manifold? And a measurement of the inlet extension!
Robbie
 

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Certainly not the end! How about a close up picture of the manifold? And a measurement of the inlet extension!
Robbie
Just from looking at the first page, I foresee a rapidly rising post count, followed by a classified ad.
Cue up the theme from "Jeopardy":rolleyes:
 

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Folks,

As Robbie points out,
'40 OHV manifolds are one-year-only because of their length, as shown on the left in my first attachment.

Bronze manifolds are the same length as all later years.

And think about what was going on in the world in 1940. Copper and tin were strategic materials, for things like bullet casings. It wasn't going to be wasted upon something that is traditonally steel or iron.
But after the War, there was a lot of cheap brass scrap.

So cheap that the castings are prone to porosities, as shown by two bubbletested in my other attachments.

I process more than my share of bronze OHV manifolds, and they are invariably, as Robbie predicts, from '47s.
I have processed one bronze U manifold that was identified, and it was from a high-digit '46 UL.

....Cotten
 

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Is there a differance in the intake manafolds from a 61" and a 74" from head to head, a friend has a 47 knuckle 74" he just put it togeather and the intake is loose,tighten one side and theres a gap at the other,any info will help
YUP.. YA GOT AN EARLY INTAKE.2 DIFFERENT SIZES~:eek: READ IGGIEAS PIECE
 

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Just for clarity Folks,

61" Knucks were 3 13/32" wide;
74" Knucks were 3 5/8" wide;
61" Pans were 3 1/4" wide;
and 74" Pans were 3 3/8" wide.

As found in Palmer's,

....Cotten
 

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And think about what was going on in the world in 1940. Copper and tin were strategic materials, for things like bullet casings. It wasn't going to be wasted upon something that is traditonally steel or iron.
But after the War, there was a lot of cheap brass scrap.
The attack on Pearl Harbor wasn't until December of 1941. Hitler declared war on the US a few days later. I wasn't until we were well into 1942 that certain materials and products became strategic. I doubt that the 1940 Knucklehead was affected by a war that didn't exist, in the US at least.
 

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The attack on Pearl Harbor wasn't until December of 1941. Hitler declared war on the US a few days later. I wasn't until we were well into 1942 that certain materials and products became strategic. I doubt that the 1940 Knucklehead was affected by a war that didn't exist, in the US at least.
Carl!

Whether the war clouds on the horizon affected material selection or not,... the 1940 manifold was still not bronze, as shown in my previous photo.

....Cotten
PS: Don't think War was not on the minds, one way or the other, of those who worked at H-D; As Herbert Wagner explains in his "H-D '30-'41 Revolutionary Motorcycles & Those Who Rode Them" (ISBN: 0-88740-894-X), German was the second language of the Factory.
 

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The attack on Pearl Harbor wasn't until December of 1941. Hitler declared war on the US a few days later. I wasn't until we were well into 1942 that certain materials and products became strategic. I doubt that the 1940 Knucklehead was affected by a war that didn't exist, in the US at least.
The war drum started beating in 36 and got real loud in 38, We did not wake up in 41 and say lets get in the war.Read your history books.We were watching mr hitler...
 
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