Dave, all...
I am by no means an expert on small block fords, however, I do have some
knowledge. The very last paragraph below caught my eye regards how to
modify an engine to get high oil pressures..
Lets look at the oil pathway first. Oil comes from the pickup in th epan
to the oil pump via a suction into a gerotor pump. The oil is then fed
to the filter and then into the oil galleries. It goes into the lifter
gallery to the cam bearing gallery and to the main bearing gallery. Oil
fed into th emains bearing gallery further goes into the crank to supply
the rod bearings. Oil that feeeds the lifters travels up the push rods
to the rocker and then onto the springs to cool them. Oil is always
seeeking atmospheric pressure and so at each of the bearings it leaks
out returning to the pan to be recycled. So where are the places to
modify the engine? Well if you have tighter bearing clearances you will
get a higher pressure...also more heat. The place that is usually
modified, by the manufacturer, is the oil pump. Th eoil pump has a
relief spring inside it which is preset to recirculate the oil when the
pressure dictated by all the stuff I mentioned above is met. So if you
have a low presure situation then most likely you have worn bearings,
particualrly the cam bearings. These see a near constant downward load
from the valve springs and that tends to wear the cam bearings on the
crank shaft side. The oil pump willput as much oil into the system as
it can handle witin the limits of the relief spring. I have a melling
blue printed high volume pump on my race car because I needed more
capacity to feed the turbo. The relief spring on the pump can be
adjusted by the user to have what ever pressure he desires. And of
course, if you go to a dry sump system you can set the pump pressure to
just about anything you want by changing the rpm of the pump. It is
interesting to note that a lot of the heat in an engine comes from the
pump because it recirculates the bypass oil. I am looking at using a
system that eliminates the relief spring in the pump and puts a regulaor
on the output side to dump bypass oil back into the pan eliminating the
continous heating of the oil. Still an dall, what pressures do I have?
Well on the race car, I use a pump that is set to 75 psig, I use 20W50
Valvoline racing oil, a large Fram HP1 racing filter. At the end of a 3
mile run pressur eat idle has dropped to around 50 psig.
Hope this helps to understand a bit more on oiling.. It can and I can
get deeper if need be.
mayf
Dave Munroe wrote:
>Thanks Tony;
>
>snip
>
>
>60 psi and up seems to be uncharacteristically high for a "normal" street
>SBF engine, and there does not appear to be a lot of info on how to modify
>an engine to produce these high pressures.
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