Help to identify center main bearing cap

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Model T Ford Forum: Forum 2016: Help to identify center main bearing cap
Top of pagePrevious messageNext messageBottom of page Link to this message  By Harvey Cash - Winnemucca Nevada on Saturday, December 10, 2016 - 06:19 pm:

My engine has developed a knock so I pulled the inspection cover from the bottom of the engine, hoping not to find mass quantities of metal. The pan was clean but upon inspection I found a very unique center main bearing set up with a spring attached. Can anyone help me identify what I have and could it be the reason for the knock. As always all help will be greatly appreciated bngbng


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Saturday, December 10, 2016 - 07:09 pm:

Harvey:
you have an adjustable "thrust" ... aftermarket center main bearing cap ...probably not the source of your knock UNLESS that bearing is too loose ...always an optimist...gene french


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Saturday, December 10, 2016 - 07:24 pm:

harvey, The problem that i have seen with the adjustable center main is it keeps pushing the crank forward. On a couple of the engines i tore down with these in it the flywheel was hitting the field coil and that will give you a knock!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harvey Cash - Winnemucca Nevada on Saturday, December 10, 2016 - 07:51 pm:

I guess my next question is, should I replace the adjustable cap with a standard? I was able to tighten the bolts holding the cap on by hand so perhaps it is just loose but in the long run would I be better off replacing it?


Top of pagePrevious messageNext messageBottom of page Link to this message  By tim moore, "Island City" MI on Saturday, December 10, 2016 - 08:00 pm:

I took one of those out of an engine also. The bearing is not bonded to the cap and under constant forward pressure. Gene and Joe are the experts here but I think a crankshaft is designed to spin in a circle and not try to screw itself forward. I hope your rear main thrust isn't gone and the rod bearings are not egg shaped by running off center. I would remove it and put it in a display case.

Good luck,

Tim Moore


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Saturday, December 10, 2016 - 08:50 pm:

Tighten the bolts on the center main and check the others, then put it back together and see if your knock goes away. Finger tight main bearing bolts could easily cause a knock.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Putnam, Bluffton, Ohio on Saturday, December 10, 2016 - 09:24 pm:

That adjustable center main cap is a band aid to cover another problem. The thrust surface on the rear main cap is worn and no longer holds the clearance needed in the magneto. Chances are you engine needs all new main bearings.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harvey Cash - Winnemucca Nevada on Sunday, December 11, 2016 - 08:06 am:

I have been unable to find a picture of this cap, When I drained the oil a nylon lock nut and a 5/16 lick washer were on the magnetic drain plug. I don't know where they could have come from but possibly part of the adjustable bearing. Does anyone have a picture of this bearing complete? The opinion of most is that I should remove this cap and replace it with standard. Harv.


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