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Discussion Starter · #1 ·
I recently built a 331 and I used a oil pump from Precision Oil Pumps.They have a website.They use Melling HV oil pumps,where they moly coat the gears and check all the tolerances of the pump.The pump that I used,was the race pump that he suggested.Saying it was a popular pump with the 331 and 347's.It has a thicker plate on the bottom of the pump that supports the shaft,therefore making it supported on both sides rather than just one as a normal Melling pump is.It also has the casting flash removed and smoothed out for better flow and it has been drilled and tapped where the pressure relief spring is at making it adjustable.Before I installed it I was afraid of too much oil pressure and followed his instructions of using the cupped side of the udjuster and I backed it out as far as I could to be flush with the surface.I was told I would have around 90lb.After I started the motor I was suprised to see over 100lb at an idle and if it warms up real good it might drop to 80lb.But as soon as I give it gas it goes up over 100lb again.I'm using 10w40 Penzoil for the break in and plan on using synthetic after that.What kind of problems can this cause,if any,and what can I do.I appreciate the help.
Thanks,Brad
 

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Discussion Starter · #3 ·
I have the 7qt oil pan.I was told using the 5w30 would help,so that is what I'll end up trying when I change the oil.If I had it to over again I would use a lesser pump.Why would someone need this much oil pressure?I was hoping the feed line to the Vortech would eat up some oil pressure,but it doesn't.Initially I was told the hydraulic roller lifters eat up alot of pressure that is whay I chose to use this pump.I should have known better as I never had any problems before.
Thanks,Brad
 

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100 psi has been knows to balloon or burst oil filters. The higher volume pumps are used on engines (usually race) that are built with more bearing clearance than street engines. With more clearance, you need more volume to maintain pressure. The pump chosen should be picked with bearing clearance in mind. When the higer volume pumps are used with tighter clearances, the pressure soars. The should be some sort of pressure relief spring that can be altered. A good rule of thumb is 10 psi pressure for each 1000 rpm -- so really stout small blocks spinning to 8 or 9 k need 90 psi; but they're also gonna have solid lifters. I don't think you'll be able to run that way indefinitely without changing something to reduce the pressure. Since you've got a hydraulic lifter set up, you're probably not seeing anymore than 6500 rpm - 60-65 psi should be plenty for your motor.
 

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Discussion Starter · #5 ·
Is there anything short of changing the oil pump to correct this problem?That will definately suck to have to change that oil pump.With that t-style pan there is not alot of room to drop the pan.What is the negetive affects of this much oil pressure other than what was mentioned.I have only seen about 35 4000 RPM at the most so far but I have an appointment with the Dyno at Anderson Ford for tuning on the 6th.I can just imagine what the pressure will be at 6000 RPM.My guage only registers 100lb.
 

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You don't want to blow up a filter on the dyno -- I'd bite the bullet before then. I don't think you'll have to change the pump - I believe the relief spring can be altered; but the pump's got to come out to do that I think.
 

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First off... whats with the mud in the engine? 10w40 is the worst oil (every brand except trrue synthetics offurd) Your running more soap and viscosity index expanders than oil.

What are your main and rod bearing clearances? Sounds like the thing was assembled in factory tight specs. That pump is deffinatly over kill for the lower end assembly.

You are going to have to pull the pump and get less tension on the relief spring. 100+psi at that low an RPM is not good. There are filters that will survive, but your waisting HP, and your putting a sheet load of stress on distributor and cam gears.

I run my pump set for 110 psi relief, and will see around 90 psi at 8500 RPM. BUT I have race clearanced everything AND added oil spray holes to the front galley plugs that lube and cool distributor gear, timming gears, etc....

If you run a FL1AHP or something like a Mobile 1 filter, or any miriad of other RACE filters you will get a 600 psi burst rating canister. You wont rupture the filter... but you could twist off an oil pump drive shaft, and or trash distributor gears.
 

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Kim, what is the deal with 10W-40 ??? why is that bad? I have always used Mobil 1 5w30 in the winter and 10w30 in the summers, and have never had any problems at all. I dont agree with Pennzoil, but its just for his break in... please explain what your referring too.
 

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the 10W is the base grade of the oil. That is how it pours at some low temperature. Kid is driving me nutz soo my head is already pounding, cant remember the test temps.

To get the oil to act like a straight 40 weight oil at some set high test temperature (say 200 degrees- its made up I foreget the real test value) the oil company has to add a bunch of index expanders to the oil so the molecules react similar to the straight 40 weight. When they add all these index expanders, it displaces regular oil molecules. The index expanders are also the crap that breaks down first....

For break in, if its a flat tappet cam, Ill us a non detergent straight 30 weight. Keeping the moly lube everywhere I put it as long as I can.

For a roller engine, Ill do the first run with valvoline or kendal (gas or alcohol) and change that oil out after initial engine warm up.

Then replace, and typically if its a street engine, prone to cold starting and cold driving abuses, I recomend a 10w30 conventional or mobile 15w50 synthetic, (remember synthetics are designed differnt.

If its a race only engine, 20w50. Higher quality base oil, fewer viscosity expanders used.
 

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Oh...kinda makes sense.... They cram all the crap in the oil to take care of most people who don't do regular oil changes, and to take care of the cold start-up and cold driving abuse that most people do.

I run strictly Mobil 1 in my car, and have since I broke in the motor. So I really have nothing to worry about.

Sorry to have "stole" your thread man.... but I guess its usefull info for us all really....
 

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I'd try some really low weight oil such as 0w30 or 5w20. Both are available from Amsoil synthetic and maybe other synthetics too. Sure beats changing your pump.

I put in new main and rod bearings in my engine when I had it out to put into the coupe. I put in a HV pump at that time too.
(Didn't replace rings or cam bearings though).

My oil pressure was like yours 100 psi at idle and would drop to 80psi when hot. I dropped to lower weight oil and it helped.

Later, the oil pressure dropped as I drove it a little and I moved up to regular weight oils at that time. But, this was a cheap and dirty engine partial engine freshen up.

Hope this helps.
 

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Discussion Starter · #13 ·
All the input is great.The motor only has about 40 -50 mile on it at the most.I have changed the oil once already to take out any particle's that might be there from start up.If I have to I'll change that spring out,but I would like to try some other things first,like the lower weight oil.Does anyone have any suggestions as to what kind.I'm probably going to go with the synthetic.I just wish I had been given the correct info when buying this pump,I would have known better.Also I have just sprung a little leak from the drain hose from the blower.I have a connector in the hose going back to the oil pan with two hose clamps that the leak is coming from.What type of hose should I use for this drain?
 

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Discussion Starter · #14 ·
Also the clearances is per DSS.I used their stroker kit with their tolerances,which differed from the stock specs.
 

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Its still to friggen tight.

I would run some 0w-30 That should net some normal oil pressures.
 

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kim what are your opinions on lower viscosity oils with a small viscosity range like 5W20 or 10W30? Are they as good as the 20W50, or do they have more viscosity modifiers than 20W50 making them less reliable?

It's funny how they box up very low viscosity oil like 0W20 as "race oil." Is this because using that oil in a tight clearance street motor results in more power? But most dedicated race engines have loose clearances for greater buffer space and thicker oil to fill up those extra gaps right?

After breaking in the motor I rebuilt in one of my cars, I've been using Mobil 1 synthetic 5W30 for less drag and still have good oil pressure... would I have been better off to have bigger clearances and 20W50 synthetic? Or is synthetic oil a whole other story? Why are factory clearances made so tight if you're better off with thick oil in a loose engine? What makes the sky blue?
 

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manns50 said:
I recently built a 331 and I used a oil pump from Precision Oil Pumps.........They use Melling HV oil pumps,where they moly coat the gears and check all the tolerances of the pump.The pump that I used,was the race pump......
I also have a 331 with one of their pumps. Mine is a Melling standard volume race pump prepped the same way. I initially installed it the way it came, but was running what I thought was too much pressure at speed. I turned the threaded spring retainer around so the cupped side was in towards the spring. I'm getting 25psi at idle and about 65 at cruise and above now. (It has a 85lb pressure relief point.)

BTW, I'm running .0022 clearance on main and rod bearings and use Chevron 10-30W.
 

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Discussion Starter · #18 ·
I have turned the adjuster over as said and backed it out and this is what I was left with.I'm going to contact them about changing the spring or altering it or something.
 

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Discussion Starter · #19 ·
I bought some Valvoline full synthetic 5w30 today with a Mobil 1 filter that is pressure rated for 5 times the pressure.I'll see what happens with this.I spoke to Precision oil pumps today and he recommended I do this.He said if I was still not satisfied he would swap me for any pump I wanted less shipping charges.He didn't see a problem with the pressures other than it eating up 5hp or so,(he said with the moly coated gears it should balance out),and the oil filter.But this is why he suggested the better oil filter which I should be using anyway.He said there was nothing that I could do to this pump to lower it because it has a 110 relief valve,and the spring is a different type adjuster springSo the pressure can't get over 110 approximately.This is a good thing! I will update this post as to how this turns out.
Thanks,Brad
 

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Discussion Starter · #20 ·
I used the 5w30 full synthetic Valvoline and let it warm up by idling,and my pressure was still over 100lb at an idle.Like I said,I spoke with Precision Oil Pumps and he did not think that it would hurt anything,stating that it's just oil.He said the older bearings might have been affected but the newer bearings are of better grade.I just have been working on this combo (as I get the money) for a year and a half.It isn't something that is easy to do.(lifting the motor up to get to the pump) The motor only has about 45mi. on it and I'm hoping that it will drop after getting some miles on it.I think I'm going to keep the appointment with Anderson and hope for the best.
 
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