[DeTomaso] Autopsy

Will Kooiman wkooiman at earthlink.net
Mon May 19 23:43:29 EDT 2008


I removed the water pump, timing chain, and camshaft this evening.

The camshaft was in 4 pieces. I removed the first piece a couple of weeks
ago.  The other 3 pieces were in the cam tunnel.  I guess I had a 3/4 racing
cam (har har har...)

The camshaft had no obvious damage - other than the collateral damage from
the bits bouncing around.  The lobes all looked perfect with a couple of
nicks.  The journals looked great.  The timing chain looked new.

I still haven't removed any mains.  My guess is they're okay except with
water damage.

I was able to retrieve the head of the intake valve.  It isn't broken where
I previously stated.  Suppose you put the valve on a work bench with the
valve head facing down and the keeper end facing up.  The valve stem is
11/32.  About 1" from the valve head, it necks down for improved flow.  It
didn't break there (as I previously stated).  About 1/2" later, it starts
tuliping out.  It broke right where it started to tulip out.  Yeah, I know,
I'll post pics.  It'll be obvious then.

I looked at the 3 spark plugs on the passenger's side.  They look great -
light tan color with no weird foreign bodies on it.  The #3 plug has the
ground electrode smashed and the porcelain missing.  There's not much to
inspect.

I'm still going with sucking in debris.  Whatever the cause, I won't run
without filters again, and I'll probably take it to a dyno before I lean on
it with the Webers.

I measured the cylinder wall thickness by comparing the wall with a piece of
wire and then measuring the wire.  It looks like the wall thickness is about
0.18" on both sides.  Is that good or bad?

I only measured in 2 places.  The cylinder seems pretty well centered,
though.

Will.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of Ken Green
Sent: Monday, May 19, 2008 5:21 PM
To: Will Kooiman; 'Pantera List'
Subject: Re: [DeTomaso] Autopsy

Is there any chance the main bearing seats and/or caps could have been
compromised?  Seems like heat and force could do that.
   
  I think it died of self inflicted wounds after hearing you say that you
were dumping it for a  Chevy.
   
  Ken

Will Kooiman <wkooiman at earthlink.net> wrote:
  The #3 spark plug is pretty much wasted. The electrode is completely
broken
off. Who knows where it landed.

I had an O2 sensor in the passenger's header. It showed about 2 clicks too
rich. That's on an autometer a/f gauge. I don't know what a/f ratio it
corresponds to. Of course, #1,#2 might have been overly rich and #3,#4
might have been lean.

The exhaust valves on the driver's side are white. I didn't clean 'em up
when I had it apart last, though, so the whiteness might be from the
previous setup.

The #3 rod is bend, but not pretzled. It's probably less than 1/4" shorter
than it is supposed to be.

Detonation on #3 sounds likely. That would explain the pounded rod journal.
The exhaust valve doesn't look burnt, but there was so much steam, etc. in
the cylinder when it let loose all evidence might have been steam cleaned
away.

Thanks for all the input. I promise to post pics when I get a chance.

Oh yeah, I'm planning on sleeving the block and using it until I get the
Chevy 307 together. Yes, I'll clean it thoroughly.

Will.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of Daniel C Jones
Sent: Monday, May 19, 2008 4:56 PM
To: Pantera List
Subject: Re: [DeTomaso] Autopsy

One scenario: The carb over cylinder #3 sucks up some debris and goes lean.
That cylinder heats up and starts detonating which pounds the rod bearing.
Meanwhile the piston is also getting hammered and eventually fails which
then pretzels the connecting rod. Check the spark plug under a lighted
magnifying glass for flecks of aluminum from the piston. Perhaps pistons
7 & 8 touched the exhaust valve when the cam broke?

> All of the rod bearings are worn. All of them are deformed.

Perhaps you were detonating on all cylinders with #3 being the worst.

Dan Jones
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