[DeTomaso] Cam problems

[David_Bell at oxy.com]

If you prelubed the engine without being able to get to the distributor
hole, then I assume you spun the engine with the starter to turn the oil
pump to build pressure. Yes?  If so, spinning the engine and squirting
oil everywhere may have wiped away and/or diluted that fancy cam
assembly lube and basically left the cam lobes unprotected.  

FWIW, I had a cam fail during initial break-in a few years ago - to the
tune of 3 flattened lobes and three ground up lifters.  I followed the
same procedure that you appear to have of lubing the engine by spinning
it with the starter until I got oil pressure, before actually firing it
up.  After about 5 minutes of break-in running, it was obvious that I
had a big problem as several of the valves began banging loudly.  One
the three damaged hydraulic lifters ended up so worn that I could see
into the hollow oil chamber in the center of the lifter.  I had to
completely disassembling the engine to clean out all those nasty iron
bits and also replaced all the bearings, seals, rings and the oil pump,
plus the cam and lifters - basically a second rebuild.

Before starting up the newly rebuilt engine the second time, I avoided
pre-spinning the engine at all costs.  This time I used a distributor
replacement pre-lube shaft and an electric drill to spin the oil pump
without turning the engine.  This filled the filter and oil channels in
the engine without washing off any of the cam lube.  The second time
through, the cam broke in completely normally with absolutely no issues.
In fact the same cam/lifters are still in the engine and going strong
after 25k miles of serious street and track abuse.

While I can't prove that the first failure wasn't related to a soft cam
blank, or not enough zinc in the oil, or some other unidentified glitch,
I will never again do the spin-the-engine-with-the-starter thing before
firing it up the first time.  


Dave Bell


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Hi all,

I need some major advice..........  I have just had my second Comp Cam
go flat in my Pantera.  The first one went in about five mins of
break-in time and the second in about ten mins of break-in time.  Both
times never below 2000 rpm.  Both times  new cams (560 lift hydraulic),
the first time I used Comp Cams lifters (hydraulic) and the second time
Crame lifters (hydraulic).  Push rods were measured and were the right
length,  double valve springs (old and weak) when tripple are
reccommended for this grind of cam,  Comp Cams break-in lube the first
time and Crane break-in lube the second time.  I used an oil accumulator
(3qt) and the oil pressure started off at 60lbs and gradually went down
to below 20lbs (new guage) and that's when I shut it off.  Both times.
New oil pump both times.  I use an engine oil cooler.  Pete Jackson gear
drive that has plenty of clearance, (new).  I pre-lubed the engine
before I put the weber manifold back on (could'nt get anything in the
distributor hole after as the webers were in the way) and the oil pumped
up through everything including the new lifters and pushrods (Comp Cams
3/8 pushrods).

I am now thinking of using a hydraulic roller cam and lifters.  I
understand that they require no break-in time.  Is this true?  I don't
know what lift and duration etc to use when ordering.  The engine is
bored 30 over with Kieth Black pistons and reworked rods, windage tray,
large oil pan, completely balanced,  Webers and 180 degree headers.  I
am after a rough sounding idle.  The car will not be raced but street
driven.  I have never used a roller cam before.  Are special valve
springs, pushrods etc needed?  Any suggestions on cam manufacturer and
lift, duration etc?  Are any modifications required in the lifter valley
etc?  

Any and all help would be greatly appreciated.  This is driving me nuts
not knowing what's causing the problem.  

Thanks in advance,

Steve