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Main Bearing Caps - 100


Jedi Knight
Hi -

I need to take the main bearing caps off the motor of my Atlantic (same motor as a 100). Dave told me they are press fit into the block.....

Is there any way to remove them with the motor in situ... or do I have to pull the motor and take it to a machine shop. I really don't want to yank the motor on this thing (the motor otherwise is in great shape)... it just has a spun/scored main bearing.

Any advice apprciated.

Dave Russell

Yoda - R.I.P
Hi Alan,
It "might" be possible to remove the caps in situ.It's going to be a real struggle though. Once you remove the transmission you will have to find a way to support the back of the engine while removing the flywheel & rear main cap.

The front cover, timing chain, & a few other things would have to be removed.

If a main bearing insert was truly spun, it's almost certain that crankshaft damage would have to be corrected by grinding which would require complete removal of the crankshaft.

I really think it would be far better to just remove the engine & do everything right,


Country flag
Hi Alan,
I don’t know if this will help you, Vping made a tool to remove pressed-in bearing caps. Here is the link .


Jedi Knight
So I guess from the lack of spirited response I take it I might as well suck it up, bite the bullet, yank the motor out of the car, and shove the crankshaft up my Khyber.


Dave Russell

Yoda - R.I.P
Here are some detail pics of my block, crank, etc. As I said, the front & rear main caps are a deep press fit on their sides. The center cap is a shorter press but still pressed. I made a tool similar to the one shown above. Additionally, the front & rear caps are bolted to the front & rear engine plates. A very strong bottom end but not easy to get apart or put back. It WAS used as a 22/1 compression ratio taxi diesel engine. Sturdy enough to run a 4 3/8" stroke at 6,000 rpm plus. (with the right crank, rods, pistons, & harmonic balancer. Maybe the attached pics will help.


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Jedi Knight
On reassembly can you just tap the caps into place with a mallot, then use the bolts to pull it the rest of the way in?


Jedi Knight
Dave Russell/Alan,
If my memory is correct an A70 crank is the same as the A90/AH 100, just the block was cast bigger for the larger displacement hence the A70 head doesnt quite cover
I put a chev oil slinger rear seal in whilst mine was apart, didnt need a lot of work, and no leak as yet /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Dave Russell

Yoda - R.I.P
healeynut said:
On reassembly can you just tap the caps into place with a mallot, then use the bolts to pull it the rest of the way in?
Yes - Pretty much so. Make sure that the bearing shells don't jump out of place while tapping.
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