Why...oil holes.

[Steve V]

Why are the thrust bearing oil hole always smaller than the other 3? Is it ok to open it up to the same size as 1,3,4..1/4 i believe.

 

[turbofabricator]

Go ahead and open it up if it makes you feel better. I don;t and have never had an issue (that was casude by the hole size anyway) Some guys drill the feed hole bigger in the block, too, but I feel that weakens the already weak block.

 

[Steve V]

Well I already did:smile: and I have been on my last 10 or so builds. Reason I ask it I got a little carried away as an experiment on a project and this motor ate the trust terrible for a street car but that hole was opened larger than the hole in the block. I suspect that had something to do with it. I have been through the trans and will verify line pressure when they are both back in the car. This was a daily driver not a beaten on car last 3k miles before i found the thrust issue.

I don't open the block or us HV oil pumps.

 

[turbofabricator]

Personally I have found that the number one reason for thrust failure on a Buick is that after a crank has been ground, say .010/.010" the crank grinder will always "touch" the thrust surface to "true it". The grinding wheel leaves what looks like a saw blade finish on the surface. I hand polish the surface with 600, then 1500 grit paper and have not had a thrust failure since. I use to frequently. Try that and see if that helps.

 

[Steve V]

Personally I have found that the number one reason for thrust failure on a Buick is that after a crank has been ground, say .010/.010" the crank grinder will always "touch" the thrust surface to "true it". The grinding wheel leaves what looks like a saw blade finish on the surface. I hand polish the surface with 600, then 1500 grit paper and have not had a thrust failure since. I use to frequently. Try that and see if that helps.

Ken,I was aware of that I do that with my ground cranks. This crank was a std/std crank. As well as the one I replaced it with,no saw marks.

 

[TurboBuRick]

Steve,

I found this to be interesting. GM High Tech