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4th Main Alignment

Posted: Tue Jun 23, 2020 3:14 am
by ArthurB
I am installing a newly babbitted 4th main on a 1926 engine. It fits the shaft like a glove. The Ford manual and Chaffin book both say to adjust the alignment with shims between the hogshead and crankcase. Sure enough, with a little pressure on a prybar behind the hogshead it slides into alignment. My question: Is there any recommendation about where to place the shims, or what size/shape shims to use? It seems like with all the vibration you would want some sort of retention, like putting a thin washer behind the bolts, but the diagram in the manual just points to the general area near the top of the hogshead. I'm sure this is obvious, but not to me!

Re: 4th Main Alignment

Posted: Tue Jun 23, 2020 4:33 am
by Kerry
It's simple enough, shims or flat washers to fill the gap between the hogs head and block at the 2 bolts at the top, if you need to pry it any. Usually nothing is required. If your ball cap is sliding ok and sits flush on hogs and pan, gasket between, then bolt it all up, no gasket on the drive shaft side.

Re: 4th Main Alignment

Posted: Tue Jun 23, 2020 9:47 am
by Adam
Use the brass laminated magneto field coil shims between the block and hogshead. You might have to make the hole in the shim bigger.

Re: 4th Main Alignment

Posted: Tue Jun 23, 2020 11:23 am
by Dan McEachern
Also, laminated Model A connecting rod shims work nicely for this purpose.

Re: 4th Main Alignment

Posted: Tue Jun 23, 2020 12:14 pm
by Scott_Conger
Dan

that's a great tip