[DeTomaso] Cam problems

[John Bentley (jab)]

Steve,

The major causes of ruining cams are:

1) Inadequate oil supply
2) Incompatible lifter/cam, wrong parts.
3) Coil bid (like Fred said) causing very high pressures and wear

Do you have an oil temp gauge?  What was the temp and pressure when you
shut it off?

On the first cam that failed, what did it look like?  Were all the lobes
ruined?  How about the cam bearing journals?

This should be easy to find when you have a failure within 5 minutes.

JB




-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
On Behalf Of steve meausette
Sent: Monday, June 05, 2006 11:44 AM
To: detomaso at realbig.com
Subject: [DeTomaso] Cam problems

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
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