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?
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. regards, Joe.
On 13 Dec 2006 13:42:29 -0800, "Craig C."
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 used.
Are you kidding? I'm just happy we're not talking about God for a change.
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.
On 14 Dec 2006 08:15:30 -0800, "Craig C."
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 foot.
You didn't ... not mine anyway.
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 luck.
No matter now ... that car and engine have been recycled and pieces of it are spread out in newer cars. :-)
On 14 Dec 2006 13:57:17 -0800, "Craig C."
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.