[DeTomaso] New Engine
JDeRyke at aol.com
JDeRyke at aol.com
Tue Aug 14 15:18:27 EDT 2007
In a message dated 8/14/07 1:06:51 AM, trevor at fougere.com writes:
<<....50% compression loss. Coolant in the oil. Coolant in the exhaust. The
same cylinder that necessitated a rebuild approx 3-5,000 miles and two owners
ago. Haven't taken the heads off yet, but I'm expecting more bad news..... >>
Worst case- start looking for a new core-engine now; coolant in the oil very
likely means the cylinder wall is cracked, or (less likely) a head is cracked.
A 50% compression drop may mean a thin piece of cylinder wall has blown into
the water jacket; this happened to us with a silver-dollar sized chunk of wall
during a competition event, from a simple backfire on an engine bored
0.030-over. Ford said that Clevelands should not be overbored AT ALL and only offered
0.003-over pistons for home-fitting.
Once you find a block, have it cleaned and sonic-checked for thin cylinder
walls. Wall thicknesses below 0.080" means the thing is only safe to use in a
truck or as a lawn ornament, not as a high-horsepower engine. Most previously
overbored blocks are in this category. Blocks with enough wall thickness these
days are few & far between- see the archives thread by Pat Orlando, Allan
Foster and others who lost 351-Cs and had to spend much time finding a suitable
core to work with. Many cautious owners have stockpiled a couple of good
core-engines for such future disasters.
Also, changing to a 351W does not guarantee the thin-block syndrome will not
reoccur. Sonic-test all Fords! And find a builder who is familiar with the
peculiarities of the early-'70s Ford V-8s.
Good luck (or at least better luck than you've recently had!) -J DeRyke
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