For sure, had to be right about the oil pump cavitating because of a
restricted pickup assembly.
I installed a new oil pump with the newer style cover (pickup arm) and the
newer style strainer assembly. The newer pickup parts have a bit larger flow
passages, a more direct flow path, and above all, more clearance below the
pickup tube. The last time the oil pump cavitated I recognized the symptoms
and got off the throttle immediately, so no damage to the crankshaft, just
cleaned it up a bit and installed new rod bearings.
So I gave it a good run this weekend, two days of autocross, do or die, no
holds barred. Saturday saw eight runs at about one minute each, a bit easy
to start, getting bolder with each run. I think I held it under 6500 rpm,
used third gear some, but other than that I ran it ragged. I picked up a
first place trophy, saved the engine for the next day.
Sunday was the acid test, the car was not going home without being run to the
limits. Five runs, all seeing 7000 rpm or higher, pushed harder on each run.
On the fourth run it was on valve float at about 7500 rpm for a few seconds
more than once. On the fifth run it was on valve float for five seconds,
followed by a sweeping left hand turn for 5 seconds at 6500 rpm, followed by
another 5 seconds of full throttle valve float, no problem. That was good
enough to chisle 7/10 second from the prior run and to take another first
place trophy.
For the weekend, the MGA did nearly 400 miles of trailer towing and 12
minutes of really hard track time. I'm happy to report that it still has 50
psi oil pressure idle, 60 psi at 1200 rpm, and the engine is as quiet as it
ever was. Once again it's a happy, healthy MGA 1500, chomping at the bit in
anticipation of next Sunday's autocross. With the new parts and good
pressure at lower rpms, my estimate of oil requirements for full lubrication
is now only 8 quarts per minute, and at 7000 rpm the other 48 quarts per
minute goes over the pressure relief valve.
All hail Lucas, and pass the Casterol.
Safety Faster,
Barney Gaylord -- 1958 MGA (with an attitude)
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