[DeTomaso] This ought to be fun...

Tue Apr 17 22:53:00 EDT 2012

AJ,

Firstly, the crankshaft was new.
Theoretically, it should have been fine.
Practically, 'we' should have checked.

The line bore was done correctly. So he says.
How can I check that? I have to trust someone, sometime, right?

OK, I left one bit out.... No, make that two bits... Just to keep you all on your toes.

I'm running a remote oil to water cooler; or is that water to oil cooler? Well, you know what I mean.
My experience, having installed one on my previous engine and knowing oil pressure before and after, is that about 10psi is lost in the hoses and cooler.

I think the oil pressure was just about right, based on that past experience. 
I should also note that I bought one of Quella's 'special blueprinted oil pumps'.
Supposed to deliver more oil with less stress on the distributor gear. I am not sure I believe that anymore...
I have a new Melling high volume pump ready to go back in now.

See how I add new variables every time a theory arises?
:-)

Your other theories on undersize, oversize, etc. are not proven, as you say, since I didn't put the block together....
This time, I will check, personally.

Thanks for the feedback!
Kirby

On Apr 17, 2012, at 9:21 PM, Asa Jay Laughton wrote:

> I'm no authority.
> 
> I say the bearing was slightly undersize, the crank was turned  
> slightly undersize or the main bore was slightly oversize.  Any one of  
> which would allow clearance of the bearing between the crank/main  
> bore, thus allowing the bearing to walk out.
> 
> The only witness I call is the oil pressure.  Personally, I would  
> think you should have been seeing -more- pressure from the get-go,  
> especially if you were tapping it above the oil filter.  I would  
> expect more like 75 psi hot at idle but I've been wrong on a lot of  
> other things.  I base my personal testimony on tapping the oil  
> pressure at the -back- of the block, using a stock oil pump and seeing  
> 86 psi.
> 
> The shop will of course deny it.  But how can anyone really know?  I  
> doubt you'll ever know what was wrong.
> 
> To borrow from the wood-working trade:
> - Mic it Twice, Plasti-gage it, and built it once.
> 
> Asa Jay
> 
> Good luck on the rebuild, I hope it all turns out.
> Asa Jay
> 
> Quoting Kirby Schrader <kirby.schrader at gmail.com>:
> 
>> Personally recovering from major depression and lack of motivation on the
>> Pantera front in Magnolia...
>> 
>> The Space City guys already know about this and we've discussed it a lot,
>> but for some reason, I'm in the mood to throw it out to the rest of the
>> collective.
>> 
>> My new 377 Cleveland engine build with less than 400 miles on it spun the
>> front main bearing.
>> I have never seen this happen, ever... and I've run the same combination of
>> block, crankshaft, rods, etc. for years and beat the crap out of it with no
>> problems.
>> Daily driver, track events, etc.
>> 
>> Facts for your consideration follow. I can get more detailed, but I think
>> the following is enough to start you thinking.
>> 
>> 1) Two bolt main iron block, lifter bores bushed, line bored, J&E pistons,
>> Eagle rods, nodular iron crankshaft from Quella, Moroso restrictors (I
>> spent a lot of money on this block!)
>> 2) Iron 4V heads, new valves, springs, etc. etc. etc.
>> 3) Comp Cams solid roller cam, lifters, pushrods, rockers
>> 4) Symptoms were that my oil pressure started dropping gradually when I was
>> driving home from the annual SCP pig roast. By the time I got to the last
>> stoplight before my house, I was down to 10 psi hot at idle. Oil pressure
>> is taken from the port just above the filter. You know it was less at the
>> back of the engine.
>> 5) There were no knocking, banging or otherwise nasty noises. Main bearing
>> problems make distinctive noises. I know. Been there, done that. Got the
>> scars. But I did not hear anything this time.
>> 6) I pulled the pan and found bearing material.
>> 7) Pulled the oil pump and it had obviously done some trash pumping.
>> 8) All the other rod bearings and main bearings look just fine.
>> 9) The front one had not only spun (when I pulled the cap, both had rotated
>> by about 40 degrees), but one half was actually partially canted out of the
>> web towards the front of the engine. I have pictures if you're desperate.
>> 10) Nothing is blue or shows signs of getting hot.
>> 11) The main cap is worn badly and has to be replaced.
>> 12) The machinist thinks he can salvage the block with another line bore. I
>> hope so...
>> 13) The crankshaft journal needs turning, obviously, and can be saved.
>> 14) The machine shop put the short block together, I assembled the rest
>> 15) I had an Accusump plumbed into the back of the block where the stock
>> oil sender usually resides. Accusump was set at 30psi.
>> 
>> Proposed failure modes
>> a) The main bearing was put in upside down - The machine shop is adamant
>> that is not the case. 'Hell, no! No way!' was the response to that one...
>> b) The crankshaft is bent - He's checking this week, but that would have
>> been very apparent during assembly, so he believes strongly this is not the
>> case.
>> c) Not enough oil pressure - On start up and later, 65psi hot at rpm, 30psi
>> hot at idle.
>> d) It ran fine while I was tuning the EFI. Other than running rich
>> initially and some issues with the ECU, I had no problems.
>> 
>> Fortunately, no other damage occurred.
>> 
>> So..... my questions....
>> 
>> Why did it fail?
>> What do I do to make sure it doesn't happen again?
>> Why me?
>> 
>> Who am I and why am I here?
>> :-)
>> 
>> Let the fun begin.
>> Regards,
>> Kirby
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> 
> 
> -- 
> Asa Jay Laughton - sent from somewhere other than home
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