Moroso billet oil pump and moroso 21047 oil pan. has good oil pressure 55-65lbs , depending on oil temp. during deceleration, the pressure dives way down, 10-20, but comes right back normal once idling back to pits?! Any thoughts on way. same oil pan on our other motor and no issues.

if other motor works,not sure why but try adding a little oil

was running 7qts as I always have in my bbc's, tried added one qt. no luck. ????

What's the clearance to the bottom of the pan from the bottom of the pick up, are there baffles with flaps to keep oil from rushing to the front. Doesn't matter what the other motor did its this one that's having an issue add another quart again, it may be keeping more up in the top end, do you have a windage tray to keep from aerating the oil

Best way to avoid low oil pressures after run...kill the motor when you lift...you can never starve the motor for oil if it is not running.

Just an observation over the years

My last motor had AFR heads and I always had almost no oil pressure in the shutdown. I noticed when pouring the oil in with the valve cover off after doing an oil change that it took forever for the oil to flow out of the head so when the motor was apart I had them open up the oil return holes in the ends of the heads and that helped a lot.

I've pretty much always seen this in my dragsters on the 1/4 mile. I guess I'm not sure on the short track.

that's what I started doing once I noticed it falling off . the pan was brand new from moroso and supposed to be designed for their billet body pumps. the clearance checked out ok when we checked it. this block has no restrictors to keep oil down? any of yall run those on a dart big m?

What a lot of racers don't understand is when you hit brakes after finish line your converter is pretty much locked up and you drive engine RPM down to nothing so oil pressure drops drastically. Watch and if your RPM is still up while your shutting down then oil pan is not doing its job!!If RPM is going down to nothing then oil pressure will follow .

Couple of things here.

First the newer oil pans are using windage trays vs screens. The trays do slow down oil return to the pan sump! I converted on pan a number of years ago since the tray was better or so I was told. After adding the tray and removing the screen, I had to add one quart more to the pan (7 to 8) or I would see a pressure drop just before the finish line.

Unless your not running a roller cam, you should run oil restrictors to keep more oil downstairs!

Low oil pressure on the shutdown is what it is, unless you run a slow combo, oil will run away from the pickup and cause this. I have not seen this to be a problem since the motor is not under load so you don't need high OP in this case,, just no one want to see zero on the gauge! So you can leave things as is, add a accumsump or dry sump setup! Pick your poison. Although I never tried, I don't think you could add enough oil in the pan to stop this and not create another problem!

quote:

Originally posted by No Fear:
What a lot of racers don't understand is when you hit brakes after finish line your converter is pretty much locked up and you drive engine RPM down to nothing so oil pressure drops drastically. Watch and if your RPM is still up while your shutting down then oil pan is not doing its job!!If RPM is going down to nothing then oil pressure will follow .

No matter what converter you have or engine rpm, if you have a fast car or dragster and have to use the brakes to slow down for a decent amount of time during the shut down, oil will run away from the pickup no matter who's pan your using. Rear sump pans are better than flat bottom ones.

Another thing to consider for those using a vac pump, this also effects the OP readings on the gauge (lower than without) but that dos not mean you have less/no oil being supplied to the bearings than without a vac pump...

quote:

Originally posted by TORQIN:
Best way to avoid low oil pressures after run...kill the motor when you lift...you can never starve the motor for oil if it is not running.

Just an observation over the years

Chris don't make the transmission builders get on ya. LOL


Michael, I have a brand new in the box Moroso heavy duty oil accumulator I will sell cheap if you are interested. Long story short I ended up with 2 of them and only need one.

https://proshop.summitracing.com///parts/MOR-23902

10-20 psi is no sweat. I went through a season with 0 for 2-3 seconds. I was kinda concerned, but my engine guy told me no problem. I neutral after the stripe to let the motor truly idle. so far this engine has lived through a completely shattered valve spring(valve hitting the piston) and a broken oil pump with 0 oil pressure after I got my slip(not sure when it broke in two). Motor still sees 7500 every pass after replacing the oil pump.

The Moroso pan I have now is worse doing this than the Milidon pan.
One thing I never understood is how having an extra quart or 2 slows you down. I would think at RPM you would not have much oil in pan and a lot up top and in circulation.
Know it does as I have heard stories of folks draining a quart to pick up some E.T. , just can't understand how it does...

Do yourself a favor and get an accumulator. If your motor hits zero it will take out a bearing eventually. Killing the motor has many downsides. Only masks the real issue.

quote:

Originally posted by Lenny5160:
I've pretty much always seen this in my dragsters on the 1/4 mile. I guess I'm not sure on the short track.

normal. Every engine I've had does this. Never hurts anything.

I use the same pan with a Moroso pump and never lose oil pressure....

But that’s because I have a 3qt Moroso accumulator.

A small very bright low oil pressure light on my dash. Never comes on.

Broke an oil pump on a burnout once years ago and never noticed the oil pressure was zero. Made a partial run before I shut it off. Crank was junk. Block needed align hone. A Low oil light would have prevented that failure and that’s why I have one. The accumulator is a real good thing to have. You can argue all you want about whether it’s needed or not. I have one....

just find it odd both motors use the same pump/pan combo, and one motor holds great pressure , even during hard braking, and one cant when on a long enough track you have to give it gas to make the turn off.

Micheal, in my opion, something is different about the oil drain back of the two motors. This one sounds like the oil is not returning to the pan as is should. That said, I agree that roller motors should use oil restrictions to keep more oil to the bearings. 30 years of building and rebuilding these things I have yet to see a down side to restrictions in a trailers to the track drag race only motor. An accumulator is a good idea.

I would agree it’s a drainback issue.

Oil accumulating in the top of the engine.

Add external drain back lines directly from the heads to the pan.

The accumulator is another way around the problem.

This message has been edited. Last edited by: SCDIV1,