Steven and piners,
I have done the pressure relief valve on several engines.
Its not too tough, you do need a lathe though.
Unless you have something physically wrong with your valve,
the releif valve mod wont cure low oil pressures at idle.
It will however raise your startup and cruising pressure.
Ive rebuilt sunbeam engines, and came up with less than ideal
oil pressure.
There are a lot of places though that should be looked at
to assure higher oil pressure.
Measure your bearings with an inside micrometer, then measure the journals.
Just becuase you paid a lot of money to have this all machined doesnt
mean it got doen right.
The oil tube that sprays oil on the chain tensioner, can/should be crimped
off at the end of the tube. Dont ask me why its open in the first place.
Worn oil pump?
The oil pump CAN be blue printed. This procedure involves setting the
rotor to end plate clearances on the tight side of good. Lapping the
end plate is also a good idea.
I just finished with my 1725 race engine, and although the engine seems
to have some unexplained noises, the oil pressure is 50+ PSI at hot idle.
The engine makes 70+ PSI at anything over 1500 RPM.
The magic here is that I modified a 1725 oil pump to use an MGB rotor set,
and extended the pump housing to accomdate the longer rotor set.
It was a GREAT DEAL OF TROUBLE, but considering the amount of oil pressure
I have on this engine, its probably the best spent money to date.
BTW, this mod yields 22% more oil pump volume as compared to the stock
1725 pump.
Jarrid
Steve wrote...
>Has anybody modified the Presure relief valve and how well did it work?
>Any problems or cautions?
>I have a Series V with the 1725 which is showing weakness in oil presure
>which seems to be caused by the relief valve (~15-45 pounds hot). The
>engine is fresh so I don't believe that it is caused by another mechanical
>ailment.
>It has a new oil pump, bearings, new rod bushings, so I would expect better
>presure. It does run great.
>Thanks,
>Steve
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