Insert Engine Information

[Mitch]

Antique Engine Rebuilding (AER)

[George Miller]

When using insert bearings in a Model A engine there has been a problem with spinning the rear bearing. I found a cure.


To fix the problem take the rear upper insert and cut a groove from the front of the oil well on the pass side to back of the well on the driver side. This will give you a hydraulic wedge effect to put oil under the rear main between the shaft and insert. Make sure you do not go beyond the rear oil well, or you will have rear main leak. It is important to put the well from the pass side to the driver side, because of the way the crank turns. It helps the wedge effect.

The problem is it is way to far for the oil to travel from the front of the bearing to the rear. The bearing is 3 inches long. I know this works because I have been doing it this way for some time. If you do not want to do it this way, you will have to leave more clearance, which I do not want to do. I like the .001 per inch rule. it has worked for me for 60 years. Now if you have pressure oiling you will not need to do this.

[Mitch]

Here is the pic from George showing the insert shell. The top pic shows the bearing with the groove , and the bottom one is highlighted to show where it goes.



FullSizeRender.jpg

[Guest]

George has the right idea.
Use inserts unless you happen to know where to get quality babbitt work.

[Captndan]

So how do you tell if you have spun a rear insert? Other than tearing the engine down.

[George Miller]

The engine will make a squealing noise and lockup.

[Mitch]

you'll need to verify things by dropping the cap