Dart big M regular or HV oil pump
 

I am assembling a dart big m based 540. Dart U says a regular oil pump is fine and a HV pump will lead to excess oil retention in the top end. Does anyone one have any reason to use a HV pump?

Would depend on Clearances, I run HV HP shimmed for 80psi, I also have loose clearances throughout... I did not have good luck running standard pumps years ago, cost me 3 spun bearings of people telling me it was not my oil pumps.... last time I went to HV HP, never another issue again.

I know that a HV oil pump was mandatory with mark 4 GM blocks because of the oil galleries, the difference is the Dart block oils the crank first then the valve train. All my experience building BBCs is 30+ years old so I am looking for someone with experience with the Dart blocks. I am aware that Dart U say not too, but they are also building car engines not marine engines....

i have used the melling,s 10778 h/v pump in many dart builds and have had great results.

I personally see no reason NOT to use one, especially in a marine build with looser clesrancing across the board.

HV it is!!

99% of Engines in cars don't run external oil coolers and remote oil filters. :)

I had the hv hp pump out of 540 bulldogs in my 572 darts last year. Oil pressure was PEGGED. I have one engine is out. Took pump apart. They use a high pressure spring with 2. 1/16 thick washers behind it. So 1/8 behind a 70 lbs spring. It's TO MUCH. I'm going to quality standard volume pump, maybe with 70 lbs spring with no shims. I'm putting port engine back in soon and running the starboard as is until end of season when I can pull it to change the pump. Even with a cordless drill and 0-20 oil cold I got 60 psi with mechanical gage at top of block behind lifter Valley. God I wish these things had external oil pumps. Dart does not recommend hv. Maybe it would be ok with 60 lbs spring. That would give good idle pressure and stop at 60. Rule of thumb 10 psi for every 1000 rpm. I like to see 65 or so. I am going to run bulldog pump with 60 spring with my drill. Before I seal up pan. Just going to keep pan up with a few bolts and a few qts of 0-20 oil. If I see more say 40-50 psi with cordless drill I'm using standard pump which I already have waiting on the bench.
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Better call dart

Also high oil pressure will start ripping up cam and distributor gears. I can show pics of mine. Just installed new roller cam. Do you really want to take that chance. Keep it under 70