Oil Pump

[roadking]

I have a question for the group. I have a '73 Mach 1 351c 2v and I pulled the oil pan to swap it out (big dent at the front) and since I did I was wondering if I should exchange the oil pump? As far as I know it's the original oil pump and I always had good oil pressure. There was a lot of sludge when I pulled the pan (I ran a engine cleaner thru it to get more sludge out), so should I just clean and reinstall the old pump or I buy a new one? And if it's buy a new one any suggestions?

Thanks in advance

Jim

 

[Hemikiller]

No harm in swapping it for a new pump. A Melling M-84A from Summit is around $45~$50 or so. Original pumps had a D0AE casting number on the body.

 

[Spike Morelli]

Most engine builders and mechanics will replace the pump as long as it's already accessable. The pump may be fine inside, but, labor costs to take it apart, inspect for any gear wear, check by-pass for free movement, and surface pump cover plate, far exceeds the price of just replacing the pump with a new unit. However......if YOU have the time, as a hobbyist, to check out your pump, you may find it's still very serviceable. That's the thing, you can't tell unless you take it apart. The pick-up screen should be closely inspected and cleaned as well. As I said, most shops will replace as a "CYA" ( cover your ass ) thing usually, you can't blame them , and the part is not very expensive.

 

[delawarebill]

yes replace it. it's looking right at u. i'd go factory if your pressure if fine now as u say..

 

[roadking]

Thanks, I appreciate the input and knowledge, with that being said I think I'll swap it out for a new one!

 

[Stanglover]

What ever you do, do NOT be temped to put in a High Volume pump. it'll f'up your stock motor.. Ask me how I know.

When I had my motor rebuilt (the first time) the builder put in a HV pump. Why I'm not sure unless he happen to have it on the shelf like the flat top KB pistons he had. A couple of summers later, the motor had to be rebuilt again under warranty thankfully because the HV pump caused the first lobes and lifters to ware out, oil pissing past them. The metal particles then took out the mains and so on. A stock Melling M84A pump will be good.

Geoff.

 

[Spike Morelli]

What ever you do, do NOT be temped to put in a High Volume pump. it'll f'up your stock motor.. Ask me how I know.

When I had my motor rebuilt (the first time) the builder put in a HV pump. Why I'm not sure unless he happen to have it on the shelf like the flat top KB pistons he had. A couple of summers later, the motor had to be rebuilt again under warranty thankfully because the HV pump caused the first lobes and lifters to ware out, oil pissing past them. The metal particles then took out the mains and so on. A stock Melling M84A pump will be good.

Geoff.

 Interesting......You know, I have either read, or, heard someone saying don't use a high volume pump. For whatever reason, although I think this is the first time anyone has outright said a high volume oil pump caused a cam and lifters to fail.

    When I overhauled my engine last, ( in 2002 ), I installed a high volume oil pump AND shimmed the by-pass spring for improved oil pressure. Cold, the Stewart Warner mechanical guage will read 70 psi at idle, ( where the by-pass opens now ), dropping as the engine oil gets hotter, to about 40 psi hot, idling. Hot running pressure is 70 psi . I have driven the car every day, my only car, without any adverse side effects to the engine.

   I do keep the crankcase over full by one quart always, and the oil pump drive shaft is an ARP unit to better handle the pump load.

   There was one glitch. At one point the roll pin holding the distributor drive gear sheared from the distributor shaft, I repaired it, and it happened again . I can only summize that this was likely caused by increased drive strain on the distributor gear to overcome oil pump resistance . The fix was to drill out the roll pin hole in the gear and shaft, and go to a larger oversize roll pin.....and, just for good measure, I added a second roll pin at 90 degrees below the original pin. That solved it. I had the distributor out this last year ( for non-related maintenance reasons ), and inspected the gear, with no obvious wear indications beyond normal. Opinions vary, but I have been driving for 18 years with the HV / HP set-up and still ( knock on wood ), running well.

Should I overhaul the engine again, I will bush all the lifter bores and restrict the oil holes going from the mains up to the cam bearings. At that point, with oil pressure loss issues dealt with, I will certainly just go to a stock pressure/volume oil pump, not that I race the car or really need modifications, I feel more comfortable knowing what's going on in the engine.

 

[Stanglover]

What ever you do, do NOT be temped to put in a High Volume pump. it'll f'up your stock motor.. Ask me how I know.

When I had my motor rebuilt (the first time) the builder put in a HV pump. Why I'm not sure unless he happen to have it on the shelf like the flat top KB pistons he had. A couple of summers later, the motor had to be rebuilt again under warranty thankfully because the HV pump caused the first lobes and lifters to ware out, oil pissing past them. The metal particles then took out the mains and so on. A stock Melling M84A pump will be good.

Geoff.

 Interesting......You know, I have either read, or, heard someone saying don't use a high volume pump. For whatever reason, although I think this is the first time anyone has outright said a high volume oil pump caused a cam and lifters to fail.

    When I overhauled my engine last, ( in 2002 ), I installed a high volume oil pump AND shimmed the by-pass spring for improved oil pressure. Cold, the Stewart Warner mechanical guage will read 70 psi at idle, ( where the by-pass opens now ), dropping as the engine oil gets hotter, to about  40 psi hot, idling. Hot running pressure is 70 psi . I have driven the car every day, my only car, without any adverse side effects to the engine.

   I do keep the crankcase over full by one quart always, and the oil pump drive shaft is an ARP unit to better handle the pump load.

   There was one glitch. At one point the roll pin holding the distributor drive gear sheared from the distributor shaft, I repaired it, and it happened again . I can only summize that this was likely caused by increased drive strain on the distributor gear to overcome oil pump resistance . The fix was to drill out the roll pin hole in the gear and shaft, and go to a larger oversize roll pin.....and, just for good measure, I added a second roll pin at 90 degrees below the original pin. That solved it. I had the distributor out this last year ( for non-related maintenance reasons ), and inspected the gear, with no obvious wear indications beyond normal. Opinions vary, but I have been driving for 18 years with the HV / HP set-up and still ( knock on wood ), running well.

  Should I overhaul the engine again, I will bush all the lifter bores and restrict the oil holes going from the mains up to the cam bearings. At that point, with oil pressure loss issues dealt with, I will certainly just go to a stock pressure/volume oil pump, not that I race the car or really need modifications, I feel more comfortable knowing what's going on in the engine.

 Spike, your experience and knowledge with rebuilding 351C's is well known here and appreciated. My knowledge is limited to the basics and my general experience. In this instance, when the motor failed, I contacted the engine builder and when they stripped it down, I was told that the cam and lifter damage along with the mains was directly due to the use of a high volume oil pump and repairs would be covered even though it was more than 2 years since being done the first time. I'm sure the pump was 'out of the box', not shimmed or anything else done to it. The shop I used was a general engine machine shop and not a Cleveland specialist, but they did have a lot of experience machining 351C's for other builders. Kind of wish I'd used one of them I know and who has built many Cleveland and other Ford racing motors, but he wanted to stroke the motor and do other upgrades including oil passages. The problem was he wanted nearly double and that was above my budget at the time. The irony was, by the time the motor was rebuilt the second time and I had paid for a set of lower comp pistons, gaskets etc. that were not covered under warranty, I had about the same money invested. I had pictures of the failed parts, but I can't find them now.

With the standard Melling pump, oil pressure is similar to yours, 70psi hot and I've had no oil issues since. 

Thanks for your response,

Geoff.