Technical > Matt Shaff's Engine Shop

Shut down causing oil starvation-oil restrictors?

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FEDNV:
I have a merlin II BBC and we have ran it with and without the oil restrictors in it (this one has the long and short one). I just pulled the bottom end to check it and found a few of the rod bearings are not good but all the mains were perfect as well as the cam bearings. We did not have any oil restrictors in it this last time and it really did lose pressure on shutdown around 10-20 psi total. Unfortunately we did not have the gopro on to see the gauges on most of the runs. 

Will the restrictors help keep more oil stay in the pan? This is also a new dragster full sump 8 quart milodon pan with high volume pump.  Runs 60-80 at idle

I am really debating an oil accumulator now as well, but will the oil restrictors help?

These bearings have about 14-16 passes

I use Brad Penn 40 wt.

One other things that is new are the rear brakes.  Went from basic GM metric calipers to full race 4 piston strange setup and it is night and day on the stopping.

One of the rod bearings and this is the worst one.

hemidakota:
I have also driven Scott's FED and I have seen oil pressure bounce to 0 psi during shut down a couple times since new pan and no restrictors in lifter passages...Pan does have windage tray and two trap doors in it if that helps.

wideopen231:
What about oil pan design? Normally thats biggest issue with starvation on shut down. Yes accumalator will be big help and cheap insurance.Its also kind of band aid to problem.Restrictors are more for keeping topend from being flooded with too much oil, which if that is problem they will help with more oil in pan.
 how about returns are they good size and free flowing?

msundstrom:
I have a similar combination only stock GM block and have run 2 different full sump pans and both were same issue, restrictors did nothing. My pans are 10 qt pans and 13 qts. of oil made it better but have never had bearing issues at any point. Is that shell an upper or lower?
Mark

dusterdave173:
John Callies owner of Morel lifters  ( and many other lifter makers ) say do Not use oil restrictors at all--it is bad for roller lifters for sure.
Milodon may be one of the most popular pans and easiest to get but even with double trap doors in mine it performs very poorly on shutdown--when talking with them they know this and tell you to use differnt pan they have that is deeper in rear though not well suited for a dragster .
In mine oil pressure can/will drop to near 0 on the guage but bob right back as soon as brakes are released
So far I have seen little / no harm in my engine and by this time I am turning very low RPM so I think the momentary low oil pressure is no big deal in my combo.
I feel like a really good made pan by a pro maker would be a big plus--feel like even a little extra depth at the very rear ( lower than rest of the pan) would end all these problems
Milodon has made some marginal parts forever yet still continue to sell the heck out of them
I have been asking for a 3/4 in pick up for the small block dragster pans for weeks and they Finally agreed to do them--after weeks of run around with them unwilling to take an order for a pick up--today they said they were "proto-typing " it so it would be a long time until I could really get one from them--Really?? Very poor service IMO
I would not run restrictors--it restricts oil to lifter wheels and axles--kills lifters
Callies says under no circumstances are you to run them with bushed lifters--I have seen them just Killed in a week end with restrictors myself.

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