How much endplay is acceptable in the camshaft?

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Model T Ford Forum: Forum 2013: How much endplay is acceptable in the camshaft?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Nathan Bright on Tuesday, June 04, 2013 - 12:13 am:

hello there,

Just wanted to double check a number. What is the max endplay a camshaft can have? Also, could a worn front seal (the one under the timer/distributor)account for extra play?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Tuesday, June 04, 2013 - 04:07 am:

Endplay should be about 0.004", but about the thickness of the timing cover gasket works too :-)

I assume you have a pre '24 cam shaft with the cut out for the lifter in the front bearing. The forward thrust bearing function isn't as good as in the later type camshaft where the front lobe is longer and a shorter front bearing doesn't need to have a cut out.

The end play problem gets worse when installing a reground early camshaft - then a thrust kit becomes necessary. You can buy it from the vendors (Chaffins make them) or fab it up yourself. It goes on the front of the camshaft between the timing cover and the timing gear nut.

In the kit there are two hardened steel washers = the same as is used as thrust washers in the 1917-27 transmissions. The brass washer has to be fitted to the right thickness - you may fit it so the cam shaft has no play without the timing cover gasket, then let the gasket give the endplay :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Tuesday, June 04, 2013 - 04:19 am:

Oh, the worn front seal shouldn't affect the thrust situation. Avoid the repro brass timer shield - they're not made like the originals and tend to get chewed up and cause problems. Felt/timer shield can be successfully replaced with the modern rubber lip seal.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bender Tulsa Oklahoma on Tuesday, June 04, 2013 - 07:58 am:

Cam shaft end play between the front bearing and the cam shaft flange should be .002 to .004". However the cam bearing hole is sometime enlarged and the cam bearing bolt will not hold the bearing in place giving you much more end play as the cam will now move (bearing and all). You can address that issue by building up or enlarging the stud portion of the cam bearing bolt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Eubanks, Powell, TN on Tuesday, June 04, 2013 - 08:38 am:

I believe for a while the vendors were selling front 26-7 bearings that were way too short. I have replaced the front bearing in both of my late Ts because of that. The new bearings come long and you have to turn or grind them to the correct fit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Tuesday, June 04, 2013 - 11:15 am:

Nathan
If you have too much end play you will get a knock that can make you think you have a rod knock. The difference is the knock is erratic (it won't be as consistent as a rod knock). It will be quite loud and disconcerting. I speak from experience. The good news is it won't get worse anytime soon. The bad news is it also won't get better by itself and it could mask a rod getting loose.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Pawelek Brookshire, Texas on Tuesday, June 04, 2013 - 12:04 pm:

Lateral movement of the camshaft was important enough that Ford added a cam shaft plunger to the Model A.
Plunger


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Tuesday, June 04, 2013 - 01:19 pm:

Dan, do you see that!!!!!! I just can't imagine somebody using something like that on this Forum!!!!

New spec's for cam bearings are .002 to .002-25 for bearing clearance.

New thrust Spec's for end play are.002.

.004 thousandths end play is .001 thousandths from not useable, or wore out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, June 04, 2013 - 04:15 pm:

I have put 4 Model T engines together. I have not measured camshaft endplay on any of them. If it doesn't knock, then I think its OK.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Tuesday, June 04, 2013 - 04:40 pm:

I wouldn't Brag on that!

Good thing they will still run wore out!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, June 04, 2013 - 07:55 pm:

One cam was virtually NOS, one was used, the others were reground. Nothing was worn out. Bearings were either very good or new.

My point is worrying about 0.001 or 0.002 difference in end play is a waste of time.


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