I have to replace some rod bearings and while I am in the motor, I mught as
well do it right. As far as a new oil pump goes, they show 2. One being a
high volume pump tha says it pumps 25% more oil. Would this be a better
replacement pump since the Dodge 5.2L engines have had oil supply problems?
Would you need to install restrictor plugs if a high volume pump was used. I
had to use restrictor plugs on a Chevy 350 I built about 20 years ago. What
would you all recommend, going with the standard pump or the high volume
pump. One other thing about the pump pick up tube. I have heard the pick up
has an opening about the size of a nickel and therefore is very susceptible
to sludge. Would it mess up the fluid dynamics of the pump if that opening
High volume pumps should be reserved for racing engines
with loose bearing tolerances, and/or extensive oiling systems
(like coolers, external filters, etc).
They put a lot of strain on the drive mechanisms, and
usually cause the distributor gears to wear or break.
Stick with a standard pump.
I put a high volume pump on a Ford 351C one time. Boy, did I regret
that! Everytime I started the engine, it blew 1/2 quart of oil out of
the real seal. Real pain in the ass cleaning that driveway everyday.
Stick to a standard pump.
I assume you initially may have chosen the high volume pump because of the
possibility of "oil starvation" to the back of the engine under a severe
load(?). I have read of the exposure in the ford 335 series v8's and have
studied some mods that run an additional oil supply line outside the engine to
the back of the block or something like that, I think it was discovered by dirt
track racers using the engine hard. I am currently building a 400 for a '79
f-250 that is still in parts but will be assembled in 2-3 weeks so any
additional detail of your oiling issue with the engine you could share would be
greatly appreciated. Like if all the rest of the oiling system was stock or had
mods been put on, did you have any problem with the distributor gear
stripping-prematurely wearing out due the extra pressure from the higher volume
pump, etc, etc.
Since this is OT, it would probably be appropriate to communicate via email only
from now on in this thread. Thanks in advance for any info you can add.
I generally lurk and do not post in the Dodge group but,
since you brought up the Ford 351 engine with which I have
at least a passing interest and knowledge of, I will take a
shot at getting flamed here.
Your problem was not the HV pump. It was a bad rear seal
which was probably a result of excessive wear of the rear
main which, in turn, was probably a result of the inadequate
oiling of the rear main in the 335 series Ford engines. I
have seen this a number of times during overhaul.
A high volume pump at proper stock pressure setting will do
absolutely nothing in an engine that has good clearances
other than maintain proper oil pressure at low engine speeds
where pressure typically drops. Any excess volume provided
by the pump is sent thru the return path in the pump either
to the pan or back to the suction side of the pump depending
on engine design just as it would in a standard pump. There
will be no additional oil forced to the engine above the
volume required to produce whatever pressure the system is
setup for. A high pressure pump on the other hand will
force more oil (higher volume) to the engine depending on
engine speed. If the pressure is set too high, even a
standard pump will run itself out of oil if the engine speed
is high enough. That is why engines that continuously
operate at high speeds as in racing have large or high
volume oil pans or dry sump systems. You should not confuse
pressure with volume. A high volume pump at standard
pressure setting will not force any more oil to the engine
than it would get with a stock pump at stock pressure
settings. Any pump set at higher than stock pressure may
force more oil up into the upper engine running the risk of
oil starvation if the engine speed is high enough. This is
especially true if an oil of too great a viscosity is also
Are you kidding? I'm just happy we're not talking about God for a
First, this was 20 years ago, so I will try with the best of my ability
to remember all of the facts. I put the high volume pump on when I
rebuilt the engine. I replaced all of the seals, bearings, etc. So,
I'm reasonably certain that the real seal was not bad.
I put the high volume pump in not because I had any solid logical
reason. Since I put in a slightly above factory spec cam and an Holly
4 barrel carb and edelbrock intake to replace the factory 2 barrel carb
and intake. I figured ... hey, I'm rebuilding this thing with spicier
parts, why not a high volume pump? So, that's what I did.
Result was as I originally stated, oil blowing out of the rear seal. I
talked to some mechanics that were friends of the family (Wayne
Calvert, builds racing engines in Denton, TX and his brother that has a
shop next to his that does shade tree work). It was suggested that I
use, from what I recall, some type of rope style seal to prevent it. I
never go that far ... I wrecked it and never worked on it again.
Didn't mean to step on any toes but, I have seen to many of
them built with the HV pump to help the oil system with
reasonable success. The original rope type seal was a POS
and was eventually replaced by a 2 piece metal seal with a
lip to better control the oil. This is probably what was
mentioned to you as a fix way back then. Another trick as
another poster indicated and, is frequently used to help the
rear main in them is to tee off the oil pressure sending
unit port beside the filter and install a feed hose to the
oil pressure port on the top rear of the block. The port
from here goes straight to the #5 main. That way the engine
gets oil from both ends. The HV - not HP - pump can
greatly reduce the pressurization time this way and help
prevent oil starvation of the rear main and cam bearings
which was/is a problem on the 335 series engines. And
again, it is not pressure you are looking for - it is
greater volume to more quickly fill the system. Another
part of the equation for a street engine is to use a 10W30
oil here in the SE which is plenty adequate instead of the
factory recommended 10W40 of the 70's. In cold climates, an
even lighter oil would be better. Current 10w30 oil is far
superior to any 1970's 10w40 oil for lubrication and will
flow much more quickly which is at least as important as the
pressure. We tried the increased pressure and a few other
items from the school of hard knocks text book on the dirt
track cars in the 70's and scrapped a few engine before we
started to sort out the 335 series oiling problems. If you
boost the pressure, you may be shooting yourself in the
Again ... this was a very long time ago, but the rope sel was the
recommendation to fix the problem. If I remember correctly the
original seal was rubber.
It only blew oil out the rear seal when I started the car. Once it got
o to idle, no problems.
I remember that I did run 10W30 to try and stop the blow out issue. No
No matter now ... that car and engine have been recycled and pieces of
it are spread out in newer cars. :-)
One of these days, I will have the time and finances to
complete restoring my 'Torino again. I have the powertrain
built. Now, it is the slow hard work of body and chassis.
A few hundred years from now, none of this will mean
anything to either of us.
You have a Merry Christmas
How many miles are on the engine? Over 70,000? Then it sounds like the stock
pump works fine. My son has a 318 (essentially same engine as yours) in a 79
Dodge with over 400K miles on it and it's been torn down once at 290K miles.
I checked the wear in the pump, it was 0.001" under maximum wear so I popped
in a NAPA rebuilt pump. With 10W-40 oil and a warmed up engine, he has 60+
psi at 2500 rpm and 15 psi at idle, 725 rpm. YMMV
Do you intend to race it? Then you might need a bigger pump, if not the
stock is fine.
The oil pick up isn't that restrictive, Chevy used a worse design for years.
Just make sure it's within a 1/4" of the pan bottom when it goes back
together. Also, get a priming tool and prime the engine before restart.
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