Melling M-54D or M-54F oil pump?
 

Folks,

I built a 68 400 engine to HO specs several years ago and broke it in on my engine test stand, but never installed it. It ran very well. At the time, I had a Melling M-54D and M-54F oil pump (both new) sitting around. I installed the M-54D because I didn't want to have issues in the future with blowing seals. Now as I look back, I question that. I'm pretty sure the M-54D has a max pressure of 60PSI while the M-54F maxes out at 80PSI. The engine is for my 68 bird convert and it will never be run very hard. Which pump would you use? At the moment, the engine is sitting on a standard rotary engine stand and it would be easy to swap out the oil pump for the M-54F if is the better choice.

BTW, do any of you have a recommendation for a cheap oil priming tool? I loaned mine out and never got it back. I see lots of cheapo ones online with lots of complaints.

Thanks
Old Joe :rolleyes:

60 psi is more then enough for 3” main jurnal 400 motor.

Anyway you can’t use a 80 psi pump without a special distributor gear.

I have run the 60 psi pump in many a race 455 with there 3.210” mains without issues.

Be sure you have a heavy duty oil pump drive shaft even with only a 60 psi pump.

I would only go to an 80psi pump if I had large(3.21) main journals and SD spec. bearing clearances on mains and rods.

I picked up a Morrso BBC distributor to oil pump shaft for $17 a couple of years ago and put it in a cordless drill to spin the oil pump.

Thanks everyone. I installed the stronger dist gear and heavy duty pump shaft when I built the engine, so I should be good to go. Happy to know the 60PSI pump should be enough.

WHICH "seals" in an engine are under oil-pump pressure?

Rear main. I suppose it doesn't really get blown, but heard of them leaking with higher pressure pumps. Guess I need to not be so stu stu dumb with my wording.

What special gear do you need for an 80 pound pump? I’m running one and running the gear that came on the distributor.

When the factory used a 80lb pump they used a larger Dizzy gear and a cam with a smaller gear on it.Those cams are pretty much not avail now.MANY people run the 80lb pump with factory gears on the dizzy and the cams.They are hard on dizzy gears.Tom

This topic is like Coke vs Pepsi. JBP recommends 80 psi pumps for long stroke engines, large bearing clearances, large main journals, and HR cams - and they have debunked many of the adverse effects myths related to the 80 psi pump use. The question of whether or not one is needed is a legitimate one, but the harm in using one is another matter. Plenty on here use the 80 psi pump without any adverse effects - myself included.

Rear main gets splash, and whatever squirts rearwards out of the #5 main bearing. It's not under oil-pump pressure.

If you have a standard gear on your dizzy and your running a 80 lb pump your ok if you have rear oil galley plug drilled to feed oil to it thru a .030” hole in that plug.

Pontiacs that had 60 psi pumps also had a cadmium plated gear for wear resistance

True story. My first ever episode of having to tear my engine apart was because previous owner put in an 80psi pump and my distributor gear and the drive gear on the cam ate each other. One of the chunks lodged in the oil pressure check ball and I lost all oil pressure. I have the low pressure pump which I built using two bottom plates (the one off the old pump stacked on the one off the new pump). Poor man's stiff plate. I can't weld so I pinned the feed tube with a set screw. I see really good oil pressure at all times. And have for over a decade. And no distributor gear wear either.

Sam

The only oil seal that might blow is the oil filter seal when cold.
Been there done that, makes one h3ll of a mess trust me.

GT

Minimum burst pressure for any decent oil filter is 300+ PSI. We ran the Boss Bird nitro Pontiac with typical oil pressure of 220-240 PSI on start up with 70 wt. oil and regular WIX spin on race oil filters. (2). Never a leak or issue with them. Typical down track oil pressure 145-165 PSI. So IMO, blowing out oil filters is a myth unless the filter is defective. M54D and M54F is the SAME pump. The only difference is the relief spring and cup that houses it. I run the 80 lb. relief pump on all my serious builds for street or track use. I suppose in theory, the 80 lb. pump would wear the dist gear a little more than a 60 Lb. pump. I have just never seen it with the extra oil hole in the rear plug. I have pulled numerous distributors out for inspection after 40-50+K miles and no unusual wear. The Pontiac engineers felt there was enough potential for gear wear to modify for the 80 lb. pump. So that might be a consideration for someone expecting 100K mile life from their dist. gear. The 60 lb. pump is plenty for a street build with factory bearing clearances. JMO.