Things were going great right up until they didnt...

Had made a few dyno pulls then started noticing a noise. Pulled the pan to find 7 and 8 rod bearings were gone. I think it was from making pulls with low oil pressure due to hot oil.

 

That looks like clearance issues to me. The transfer of heat does not lie.

 

7 and 8 were .0023", the other rods were .0025 to .0026

 

If you had low psi due to the oil being at operating temp,...you had a oil delivery problem

 

Was the pump primed properly?

 

Yes

 

Was this on the chassis dyno? You had the engine dynoed in early Dec correct?

 

Ive never had a buick with a balance like myself,..the one engine I did have it Jim Burek built and it lasted 150miles and eat itself

 

No, engine dyno still. The dyno shop let me me keep the engine there (I won't need it for a while) for a few weeks while I was sorting out another carburetor to do one final pull or 2. Finally got the carb finished and while warming it up, the noise started to develop so we stopped.

 

Wow, that **** got hot!
Either way that sucks, being it happened so early ( zero miles) I'd be looking at a dry start up, assembly error?
What weight oil?

 

were the Molnar rods checked for concentricity before installation and final clearance checked?

 

We are dealing with Molnar here, not Eagle... so the odds of one of those weight matched to the gram rods in that set being out of round, are slim to none..

Classic rod bearing failure due to low oil pressure, he reported at least one pull with oil pressure in the 50's at the gauge.. if he is reading off the front of the motor, that is oil pressure in the 40's back at number 7, and I would expect that damage with that oil pressure, with this much cylinder pressure.

JW

 

Just made an inquiry.Take it for what its worth.

 

I get all the top stuff,GRP,Oliver,etc,but ALL gets checked. Yes,they have a better reputation,but everything gets checked.

 

Sorry Gary, did not mean to sound combative.. it's a fair question, and one I would ask if the motor had 70+ psi of oil pressure.

But I saw that and laughed, having checked the big and little end of every rod, in every set of Tom's rods I have used for the past several years.. In over a dozen sets, I have yet to find one bore even a tenth different.. let alone enough to cause an issue.

Tom's stuff is about as good as it gets..

I have not seen an issue, but I am part of an engine builders forum. and there has been a lot of talk that the latest Oliver rods are not what they used to be. The last set I used was several years ago, and they were fine, but others have found lots of issues with them lately. So Beware Brian.. The consensus in the industry is that they have slipped off the perch they sat on since Tom Molnar was the chief engineer for them, almost 15 years ago.

JW

 

Be interesting to see dyno sheets with oil pressure....

 

What rpm was it turning?