Greetings All,
I'm planning on pulling my engine soon to seal up some oil leaks on the bottom end and figured I may as well replace the oil pump while I'm in there. I'm looking at the Melling M-57 and am wondering, since the MEL isn't a priority main oiling system, is it a better choice to run a high pressure or high volume oil pump instead of a stocker? I'm aware that bearing clearances dictate oil pressure and I plan to refresh the bearings if necessary, but the engine is installed in a '66 F100 and is basically stock except for some carburation/ignition updates.

The only advice I really found on this forum was someone stating a high volume was well worth the extra cost but didn't elaborate on why or what their setup was. Do anyone have any experiences they'd be willing to share? Thanks!

According to a local builder who has done a few of the MEL engines the FE oil galley modifications can be done to the MEL. I've seen a couple he did. As for an FE I have done a few blocks with 7/16" galleys and all screw in plugs. At times an FE could loose an oil galley plug. One reason for the latter blocks to have screw in plugs on the rear. I would do screw in plugs if installing a HV pump. There is a shop called Precision Pumps around Michigan that rebuilds oil pumps and has other parts.

Haven't ran my MEL yet so I can't give an experienced comment. I do know the crankshaft journals are wider than an FE to take the lugging that the big Lincoln's did with tall gears.

This is actually very helpful and spurred me to read up on FE oil system improvements. I've been looking at Precision Oil Pumps too and while they're spendy compared to a stocker, they're probably cheap insurance in the long run and hopefully eliminate oil pressure variables because of pump tolerances. For me, stock versus HV will depend on how much work I end up putting into the oil galleys. If I open things up significantly, I'll go HV. Otherwise, if things look decent, I'll stick with a stock pump since I don't plan on running larger bearing clearances.

On another note, I put a bar on the crank last night and discovered there's a ton of slack in the timing chain. I assumed the engine had been rebuilt sometime in the past, the plugs look great and show no signs of oil consumption, so either an old timing chain was reused or things are worse than I thought. There does seem to be a little blow-by coming out the breather cap at higher rpm, but vacuum is steady and strong. I'm going to pick up a compression tester very soon and get a proper diagnosis on it. Hopefully resealing the bottom end won't turn into a full-on rebuild.