Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Cam End Play

Cam End Play

Moderators: Curt!, Pa

Post Sat Feb 10, 2007 10:17 pm
JIm

Posts: 801
Location: Planet Earth
What would the minimum and maximum end play for the cams on a UL be?

J

Post Sun Feb 11, 2007 1:53 am

Posts: 630
Location: belgium
Jim : 0,0005" to 0,001" clearance in bushings, free to 0,007" endplay
Stéph

Post Sun Feb 11, 2007 11:03 am

Posts: 640
Location: Wisconsin, USA
I don't think you should ever assemble a motor with a fresh gasket at less than .005 endplay on the cams. If you only leave a couple of thousandths and retighten the screws after a good breakin, they will be too tight. I try to end up with close to .010 on the bench.

Post Sun Feb 11, 2007 11:06 am
JIm

Posts: 801
Location: Planet Earth
Steph,

Guess I should have worded differently. Looking for a clarification of what the manual says. I know it says what you posted but trying to settle a dispute with someone.

Question should have been, what does the term free in the manual actually mean? Does that imply a lot or a little end play and would the .007 end play listed be the max or min?

Jim

Post Sun Feb 11, 2007 2:56 pm
Pa Site Admin

Posts: 5798
Location: Ohio USA

I don't like the term freeplay either. Reasons already given. .010" is a great number with a fresh gasket too. Pa

Post Sun Feb 11, 2007 8:40 pm
JIm

Posts: 801
Location: Planet Earth
Thanks guys, answers the question and hopfully settles the dispute. Now I'll just tell the person to read this.

Jim

Post Sun Feb 11, 2007 8:42 pm

Posts: 202
Location: Middle England UK
JIm wrote:
Steph,

Guess I should have worded differently. Looking for a clarification of what the manual says. I know it says what you posted but trying to settle a dispute with someone.

Question should have been, what does the term free in the manual actually mean? Does that imply a lot or a little end play and would the .007 end play listed be the max or min?

Jim


"free" is free to turn (not binding) but no end float.

MIN=free MAX=0.007"

Post Mon Feb 12, 2007 8:32 am
JIm

Posts: 801
Location: Planet Earth
I guess we still have a difference of opinions!

Jim

Post Mon Feb 12, 2007 9:28 am
Pa Site Admin

Posts: 5798
Location: Ohio USA

Yeah Jim....free is exactly that but when dealing with gasket shrinkage and the retightening of screws over time, it may be best to insure adaquate clearance for such. If you start with just free, rotating parts will bind up over time due to the gasket inconsistancy in thickness. Pa

Post Mon Feb 12, 2007 9:57 am
JIm

Posts: 801
Location: Planet Earth
Pa,
I have always set them between .006 to .010.

Someone I have been talking to seems to think they should be between .002 and .004.

His opinion is that as the case and cam cover heat up the clearance between the cams gets greater. He states that the cams will not expand as much as the case and cam cover causing the clearance to increase.

My thinking is, the aluminum in the case and cam cover will heat up faster than the steel cams possibly increasing the clearance at first. As the heat increases and the case and cover reach running temperature, the clearance may actually decrease some due to the bosses that hold the cam busings in the cover expanding in the other direction. Then add in the expansion of the cams and the clearance further decreases down close to the initial setting. Add in re-tightening the cam cover at least once, and it can possibly close up a bit more.

Maybe I am wrong or just being anal.

Jim

Post Mon Feb 12, 2007 11:47 am
Pa Site Admin

Posts: 5798
Location: Ohio USA

I'm prone to agree with you Jim. Pa

Post Wed Feb 28, 2007 4:20 pm
I always shoot for .010". It really is a no-brainer. Better safe than sorry and you will never go wrong with .010". The little extra clearance will never, ever cause any problems or decrease the longevity of an engine (too tight though will!).

Post Tue Mar 13, 2007 1:49 pm

Posts: 530
Location: Ogden, Utah, USA
Just how thick is the cam cover gasket? If it compresses 1/2 of its original thickness would that make it unuseable? Set up the "end play" with no gasket at a light but free run and you should have no problems. Last gasket I looked at was about .0010 in thick. If this is a bad idea some one will correct me for sure. :)
Steve H


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