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Antique Engine Rebuilding (AER)
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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. -
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.jpgLast edited by Mitch; 06-10-2017, 08:54 AM.Comment
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George has the right idea.
Use inserts unless you happen to know where to get quality babbitt work.
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So how do you tell if you have spun a rear insert? Other than tearing the engine down.Comment
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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...06-04-2017, 11:57 AM -
Note the info corrections to this article starting on post # 30
The following topic covers adjusting the Crankshaft Main Bearing and Connecting Rod Bearing for babbit bearings. This should be a part of your routine maintenance on your babbit engine,performed once every ten thousand miles to insure full bearing life.The following will demonstrate the measurement method using both plastigage...01-15-2018, 05:31 PM -
I have tried this on ‘another Model A forum’ ... but ... you know !
I’ll try it on this very serious forum for a change. For a couple of months now I find myself being annoyed by the presence of the famous spiral grooves in Model A Babbitt bearings. I can understand someone adding some sort of oil groove in the upper half of a crankshaft bearing - helping distribute the oil - but never...06-01-2021, 03:51 PM -
An automotive engine machinist informed me today that he doesn't believe Model As should run insert bearings because they're not pressurized.
Is this true? What are your experiences with insert bearings in a Model A engine?11-12-2018, 04:27 PM -
Contemplating a new engine build. 7 to 1 compression,late B high lift cam,single downdraft, header,mechanical advance distributor..Dont believe in dynos and horsepower readings but for sake of argument lets say it puts out 80hp. Plan on a lightened flywheel,V8 clutch and counterbalanced crankshaft and want to 'tour' with it..got a mitchell behind an A trans with 3.78 gears,very happy with the combination.I...08-23-2020, 07:39 PM
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I am reaching out to members in the US because it is a very different market over there with stuff available that would be very difficult or impossible to find here. First, some background:
One of my cars has a B engine fitted which runs beautifully. It is my favourite and I think the counterweighted crankshaft is a large part of that. The bearings have inserts. I do not see inserts listed for...05-30-2020, 09:53 PM -
Just dropped the sump (looking for the source of an oil leak around the rear main bearing) and found some metal under the baffle at the front that I can’t identify. A couple of the pieces are fairly substantial - the biggest one is around 20mm Long and 5mm thick. Any clues on where to go looking? The engine has been running OK with no odd noises. It has an engine reconditioner label on the side,...You do not have permission to view this gallery.
This gallery has 2 photos.05-25-2018, 11:12 PM -
If you're going to have an engine rebuilt all the way why would you use babbit instead of insert bearings?09-12-2017, 08:59 AM -
Well, what started out as a drop the pan and adjust the rear main cap has come to a screeching halt.
Sorry I didn't take any pictures today, but if I remember to, I will try to get a few shots tomorrow.
So, to explain the reason for stopping, and the following discoveries, please read on.....
After dropping the pan and because there was a complaint of loud noises...04-30-2019, 09:01 PM -
I dropped the pan n my 1930 coupe today to check clearances on the main and rod bearings. Started with the rear main and found the Babbitt in the cap is cracked....You do not have permission to view this gallery.
This gallery has 2 photos.11-28-2020, 07:38 PM
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