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Oil Flow to Rocker Shaft.
Posted: Fri Jan 12, 2001 1:40 am
by Roger Muir
I read with interest a suggestion to put an oil flow restrictor in the
feed to the rocker shaft on an XPAG engine.
Has anyone any experience or advice with the oil flow to the rocker shaft
on an MPJG "TA" engine.
My engine has been fully rebuilt on the bottom end but I have not had the
rocker shaft assembly restored / overhauled yet.
Anybody suggest a UK source for this overhaul job?? ALSO?? SOMEONE TO
OVERHAUL THE OIL PUMP
It does cross my mind that if the flow to the rocker shaft is unnecessarily
high because of wear I may be reducing FLOW to the lower half of the
engine.
NOTE I AM NOT TALKING PRESSURE IT'S REASONABLY HEALTHY AT 45 - 50 WHEN
COLD. DROPPING TO 40 WHEN RUNNING HOT.
Regards Roger Muir (Bromsgrove UK)
Re: Oil Flow to Rocker Shaft.
Posted: Fri Jan 12, 2001 6:54 am
by CFritz7001@aol.com
Roger,
It seems to me that if your engine is showing an oil pressure reading of
40psi (hot), you have no cause for concern about oil FLOW being reduced to
the engine's bottom end even if the rocker assembly is getting "excessive
flow" due to wear. My logic is this:
1) The pressure measurement is taken at a point which is downstream of
the oil feed to the crank & mainbearings. In other words, the pressure is
being measured after the mains have already received their fair share of oil
2) The oil pump is capable of moving a greater volume of oil than the
engine's bearings can handle. That "over-supply" is what shows up as
"pressure", and explains why there is a "pressure-relief valve" adjacent to
the oil pump.
I'm sure that someone in TABC will correct me promptly and in detail if
my logic is faulty, but I'm hoping they'll also be gentle in doing so.
BTW, seems to me that a pump able to maintain 40+psi (hot) is not in any
great need of an overhaul.
Regards,
Carl Fritz
TC #6756
Gainesville, Florida