oil pump?

[64 200 ranchero]

which is better the aluminum or the cast iron, mine has a bad valve on it, i get different readings from day to day, one day it shot up to 100 psi but it usualy stays at 20 or 30 which is out of my comfort zone since my engine it constantly at 3500 - 4000 rpm on the freeway

 

[bubba22349]

I like to use the Melling pumps they are cast iron

 

[64 200 ranchero]

thats what i thought would be the better choice, i hope im not hurting the engine by driving it, but i have no choice

 

[bubba22349]

Have you tired to take it apart and clean the valve and check the rotor and end plate for wear? We used resurface the end plate back flat to get clearances to spec and also shim the spring or replace with a stronger one to boost pressure a little that was in the low buck / no buck old days.

 

[64 200 ranchero]

i was thinking of doing that too, but wasnt sure if it would work

 

[64 200 ranchero]

i poured some tranny fluid in the oil, it helped a little, im sure its a dirty valve

 

[bubba22349]

one day it shot up to 100 psi but it usualy stays at 20 or 30

I would say you are right has to be a reason it went to up 100

 

[64 200 ranchero]

yeah, i think ill open it up this weekend and see whats up

 

[64 200 ranchero]

well i opened it up yesterday and found out that the inside of my engine is very clean, no sludge or metal, i opened the oil pump and it looks like it might be the original, it had a c5 stamp on it which is the same year as the block, the pump looked very beat up inside, it had alot of scoring on the walls, the rotor was all scratched up, the bypass valve was beat up, so i took the valve out, polished it, and shimmed the spring, now i get from 40-50 psi while driving, when i get off the freeway it still gos down to 20 which is kinda low but should be ok at idle, i dont know how long this quick fix will last

 

[bubba22349]

The old Hot Rodders rule of thumb was 10 psi per 1,000 rpm. I would say the 20 is safe at idle and you would be doing well with the 40 to 50 range on freeway. At least you have time. Is it a high mile engine with loose clearances? If so you can use a HV type pump to take care of that.

 

[64 200 ranchero]

i was told by a member it was rebuilt and had low miles on it, it looks like whoever rebuilt it used some of the old parts insted of geting new ones, when i took the water pump off, the pump was very old but the block looked very clean on the inside like it was hot tanked, when i took the head off, the pistions looked new under the carbon, when i took the oil pan off it looked too clean to have much miles on it, but then i do change the oil about every 2-3 months, my chain didnt look too good either, it is kinda loose

 

[bubba22349]

I am not opposed to using parts over if they are still good like external items that are easy to change. How was the pumps end cover plate (true) and the rotor to case clearance?

 

[64 200 ranchero]

the end plate wasnt that bad, a little scratched, the rotor and case were badly scratched and there was a bit of clearence compared to a new pump, the pump was aluminum

 

[bubba22349]

If you have access to a surface plate or thick piece of glass and some wet & dry sandpaper you could clean up the plate and also reduce the pump case to rotor clearance.

 

[69.5Mav]

While you have the pan off you might consider plasti gaging the rod bearings. If they are loose it could bleed off some of youre oil pressure.

 

[64 200 ranchero]

i thought about checking the berings but, i only have a day to do all of this, i have to drive the car to work, by looking at the pump im sure thats the problem, it was badly worn, im always taking my engine apart so im sure ill get arround to it one of these days

 

[64 200 ranchero]

i put the new pump on today, i used a melling, now i get from 45 at idle to 60 driving, thats just about where i wanted to be for my high rpm driving

 

[bubba22349]

Thats just right

 

[wsa111]

Several years ago we disscused melling oil pumps.
You don't need 60# off idle or even 45# at idle.
Upon inspection of over a dozen melling pumps we found scoring due to too tight a clearance between all measuring areas, too little gear to cover, gear to housing & tip clearance gear to gear.
You only need 45# above idle with 10W-30 oil & 25-30# at idle.
High pressure places double the load on the distributor driven gear & the camshaft drive gear. No wonder there are too many gear failures.
I clearance all my pumps & shorten the relief spring.
Melling must think all their pumps are installed on engines which are already worn out.
When it comes to distributor gears the best is crow cams gear from austrailia, next is an AC delco gear which has been hardened by nitriding then parkerized & last is an AC delco gear which has been parkerized.
Classic inlines has some gears which will last & i have some nitrided & parkerized gears which are close to 45-50 rockwell C scale in surface hardness. All cams come with over 50 rockwell C in hardness.
If you buy a foreign gear from autozone-advance it might be 25 rockwell in hardness. Wipe out time. When the distributor gear is scored it in turns scores the camshaft drive gear. Bill

 

[MPGmustang]

what kind of oil pressure guage are you useing to watch it? is it electic wire or do u run a tube of oil into the cab?