Cam Bearing Clearence 1/16"!

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Model T Ford Forum: Forum 2015: Cam Bearing Clearence 1/16"!
Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Monday, July 20, 2015 - 11:49 pm:

A friend was putting a new timer on today and when tightening the brush holder he noticed the cam moving up and down at least 1/16". Not good. What parts would you expect to see damage/wear on. What would you look at replacing. Thanks for any suggestions, PK.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Tuesday, July 21, 2015 - 12:29 am:

If it's that worn, the block could be flogged out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Tuesday, July 21, 2015 - 12:46 am:

This motor was rebuilt about four years ago. That's why this is unexpected. PK


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting, Clare, Iowa on Tuesday, July 21, 2015 - 01:23 am:

Check to see if the Key is gone on the part lines of the front cam bearing, and check the end play, it should be .002 thousandths.

Herm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Patrick Martin on Tuesday, July 21, 2015 - 02:19 am:

How could the block be damaged at all????? The cam rides in babbited iron inserts and worst case scenario it would seem he'd just need new inserts and a new cam. Probably just needs new inserts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Tuesday, July 21, 2015 - 03:25 am:

Patrick, I don't know what, maybe a bent cam shaft? but for some season the bearing can wallow about in the block, I have seen several cam bearings over the years with shim stock rapped around them to try and eliminate play in the block.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Justin in South Africa on Tuesday, July 21, 2015 - 03:49 am:

Hi Pat,

When I rebuilt my motor my cam was moving around at the timer side as well.

I sent the cam off for re-grinding with Glen Chaffin, so if it was bent, maybe the grinding guy sorted it out, who knows... but what Glen suggested, and I did, was replace the two cam bearings with new (I think Oversize) and have them refitted by Glen while he had my cam. They fitted in my block a heck of a lot better than the old ones...

Then, when I re-assembled , I replaced the rear bushing, and checked it for straightness with my machinist who found it was off at the rear bushing by 0.3mm or 0.0118"

A line bore later and we were back in business.

That was the problem I now believe, but regardless... the problem is corrected.

I hope this helps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Alan George Long on Tuesday, July 21, 2015 - 05:22 am:

Sure the clearance between the two half bearings to camshaft journal may well be in specification however it's the close tolerance fit of that unit within the engine block is often overlooked and commonly found to have excessive clearance.
Cheers Alan


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Tuesday, July 21, 2015 - 06:32 am:

Alan has pointed to a problem not uncommon. The last two new bearings I ordered were of different outside diameters. The front one fitted the cam well and was a close slide fit in the block. The centre one fitted the cam well but measured .015" smaller in OD and thus was loose in the block.

I now check even the new bearings.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould, Folsom, CA on Tuesday, July 21, 2015 - 10:25 am:

Ford used to make oversized cam bearings. By that I mean the shell was oversize to fit a worn hole in the block. Very common. In my experience, most front holes have wear, the bearings are no longer a light press fit. But Pat is talking about 1/16th of an inch. So its not an oversize hole. Certainly appears that the front cam bearing is damaged. Although I have seen a worn front cam journal to the tune of 12 thou, its hard to envision 1/16th inch wear on the journal. My suggestion would be to remove the cam and bearings to see what the problem is. I have never tried it with the engine in the car, but it can be done by removing the head, carb and manifolds, removing the retainer pins on the valve springs and holding the lifters up with clothes pins. Of course the radiator must come off.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Tuesday, July 21, 2015 - 10:47 am:

Sounds like the cam needs to come out and see what's up. I'll try and convince the owner that a tear down is needed. If we get there, I'll post info and pictures of what we find. Thanks for all the help. PK


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