[DeTomaso] This ought to be fun...

Daniel C Jones daniel.c.jones2 at gmail.com
Tue Apr 17 14:15:46 EDT 2012


> 1) Two bolt main iron block

Still a 2 bolt main block?  With a solid roller cam and the way you use it,
it should be converted to 4 bolt mains.  Is there any evidence of cap walk?
I'd be installing something like the Bessel main caps if I were you.

> 12) The machinist thinks he can salvage the block with another line bore.

Another line bore?  Each time you weaken the caps and move the crank closer
to the cam.

> nodular iron crankshaft from Quella

Is this still an offset ground 351C crank?  Was it crack tested?

> 6) I pulled the pan and found bearing material.

For future refence, you can just cut the filter open to look for bearing
material.  Had to do that recently on my sister's Isuzu which spun a bearing
(towed it from Cincy to St. Louis so I could rebuild it only to find the
frame is terminally rusted).

> 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.

How tight is the main cap?  They should be interference fit.  When
they start to walk, they can loosen up.

> 13) The crankshaft journal needs turning, obviously, and can be saved.

Have it magnafluxed for cracks.

> 15) I had an Accusump plumbed into the back of the block where the stock
> oil sender usually resides. Accusump was set at 30psi.

I wonder if something caused the bearing clearance to change (loose cap,
cracked crank, etc.) or a piece of debris in the oil passage leading to
the front main and the Accusump saved the back bearings?

The downside to restrictors is the small passages are very easy to clog
with a bit of metal or RTV.  That's why Ford made them so large in the
first place (so they'd still flow even when people never change their
oil).

Dan Jones

On Tue, Apr 17, 2012 at 10:40 AM, Kirby Schrader
<kirby.schrader at gmail.com> wrote:
> 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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