Leyland P76 Modified cam & rockers Caution

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ACN: 006 798 492  ABN: 74 006 798 492


Dismantler’s inspection & failure analysis responsibility pays off.

An old P76 Leyland V8 came to us after failing prematurely after a “hot-up” done by another shop. The engine had been nicely fitted into a Triumph Stag, but not run until after a complete restoration of the car had been completed some two years later. The owner reported that it kept up with his mate’s Holden VL turbo and he was happy except he could hear things that shouldn’t be there.

During the strip down we found a badly worn crankshaft, worn oil pump, and evidence of foreign matter having gone through the engine. Looking further we found that the push rod balls mismatched the adjusters that had worn into the Yella Terra roller rockers. (5/16 into 3/8) Bingo; found it………well that problem anyway.

The engine was running a solid cam profile, and despite the 60 lbs on seat valve springs, gave the owner what he wanted. We stuck with the profile and had it reground with the lifters and proceeded. New springs gave the 120lbs we wanted.
At assembly, we put the oil bottle on the oil system to bleed it and confirm oil pressure etc. to then find no oil getting to the rockers.
Stripped the lifters down, confirmed that we could get oil to the oil gallery, then into the lifter and couldn’t work out why oil wasn’t getting passed the lifters during our test.
Then we recalled that some lifters are deliberately choked down to restrict oil flow up the push rods so as not to flood the rocker covers under racing conditions.
The engine builder that first did this engine is called a catalogue builder by us. They get their info from sales people and their glossy mags.
We swapped one lifter to a conventional anti-pump hydraulic lifter and we immediately had the oil flow rate expected.

Got the client in, showed him the problem, he readily paid another $1K to have the cam out and the profile reground for hydraulic lifters and we now proceed on with anti-pumps having found what we believe was the REAL problem in the first build.

An experienced and observant dismantler and then the right disciplines at assembly have to identify these problems. Despite the owner paying for some of the problem, we still lost a lot of time on the job getting it sorted. We trust that this newsletter saves you sometime.