Main Bearing Fits Loosely in Billet Main Cap

[WE2Regal]

I've got a main bearing that doesn't fit tightly into a billet main cap. It doesn't snap into place like it should. There's no play but it's loose enough that when you turn it over, the bearing just falls out. Tried other bearings and they fit the same way. The cap is a newer one made after Pro Gram Engineering was sold to Billet Speedworks. Is this bearing just going to spin on startup?

 

[BEATAV8]

Aftermarket caps need to be fit & honed for bearing crush & main clearance.

 

[WE2Regal]

The block and caps were align bored. The bore was checked and in spec.

 

[PSID6]

The block and caps were align bored. The bore was checked and in spec.

Are you measuring this yourself or is someone telling you it’s in spec?

 

[PSID6]

I've got a main bearing that doesn't fit tightly into a billet main cap. It doesn't snap into place like it should. There's no play but it's loose enough that when you turn it over, the bearing just falls out. Tried other bearings and they fit the same way. The cap is a newer one made after Pro Gram Engineering was sold to Billet Speedworks. Is this bearing just going to spin on startup?

If it was finished with a stone mandrel they might have not taken out the extra stones on a V8 mandrel and it could have hogged out one of the main caps cause the Buick 109 is so short

 

[WE2Regal]

I was there when it was measured by the machinist and saw the gauge. I don't remember what the spec was but I got it from Richard Clark. It was within that specified tolerance. Ran the gauge through the entire block and even turned it to check. (The block was machined months ago.)

 

[PSID6]

I was there when it was measured by the machinist and saw the gauge. I don't remember what the spec was but I got it from Richard Clark. It was within that specified tolerance. Ran the gauge through the entire block and even turned it to check. (The block was machined months ago.)

What main bearing are you using?

 

[WE2Regal]

Clevite.

 

[WE2Regal]

I should have mentioned this is the #2 thrust main bearing. I tried the bearing on the original stock cap and it fits tight. So tight I had a hard time getting it back off without ruining it. I suspect the thrust sides of the billet cap was machined too much by the manufacturer and is making the bearing loose.

 

[PSID6]

I should have mentioned this is the #2 thrust main bearing. I tried the bearing on the original stock cap and it fits tight. So tight I had a hard time getting it back off without ruining it. I suspect the thrust sides of the billet cap was machined too much by the manufacturer and is making the bearing loose.

You should measure the width of the main bearing the stock cap and the billet cap and see what the differences are. I am still suspect of the housing bore cause it should hold the bearing. Should be .870 wide

 

[WE2Regal]

Whatever the cause, there doesn't seem to be an easy fix at this point. Too bad. I had a lot of money in that block. But have already decided to start over and had a NOS block I've been saving machined. No way would I trust it enough to put an expensive forged rotating assembly in it.

 

[PSID6]

Whatever the cause, there doesn't seem to be an easy fix at this point. Too bad. I had a lot of money in that block. But have already decided to start over and had a NOS block I've been saving machined. No way would I trust it enough to put an expensive forged rotating assembly in it.

Yes unfortunately it can not be run like it sits. Is it a 109? What bore size?

 

[WE2Regal]

It's a late '85 block with the 20 bolt oil pan. It was a sweet low mileage NA block. But for some reason it had to be taken to 3.840 before it cleaned up.

 

[Turbo Archie]

If it was finished with a stone mandrel they might have not taken out the extra stones on a V8 mandrel and it could have hogged out one of the main caps cause the Buick 109 is so short

And you wouldn't see that on a bore gauge??