Fresh 401, Quest for Oil pressure

Hahaha! Maybe they had a bad sender? If this was a 304/360, I'd run it til it puked, then swap with another. But with the cost of replacing a 401 crank, rod(s), and block(s) these days, I am pretty scared of damaging any of those. 

69 ambassador 390 wrote: Thicker oil is not a band aid.  10 w 30 is a bit too light for these old engines.  10 w 40 was the standard back in the day.  On the clearance for the oil pump, I stated side clearance not end clearance.  What is your gear to housing clearance ?   I have always run 20 w 50 in mine since I got it in 1992.  240,000 hard miles later, I rebuilt it because I was re-doing the car.  I replaced the original pistons and bored it for the first time.  The engine was Std. till then.   I had done a re-ring once and a couple of valve jobs in that time.  I put hundreds of passes on the original lower end and got a best of 12.91 at 108 Mph.  It had several cams over the years.  I added dog leg ported heads and Headman headers.  I flogged it with 3.91 gears for a couple of years and got it up to 157 MPH on the New York State throughway one time when the throttle jammed while passing a line of trucks.  This was on 3.15 gears.  It was over 6000 RPM for at least ten seconds that time.  All this with 20 w 50 synthetic from 60,000 miles when I bought the car.  You should not run synthetic yet,. till it's well broken in, but don't be afraid of the heavier oil.  Synthetic was good for about 8 PSI at idle over the same conventional oil.   The reason I mentioned gear side clearances, is that I had an issue with a brand new famous brand cover when I rebuilt my engine.  I bought the fancy cover kit and the fancy pump gears.  I checked only end clearance because the rest was supposed to be proofed by the seller.  After warm up, I had very low oil pressure at idle and only 30 or so on the Hwy.   I found this unacceptable and started measuring.  I found the side clearances way too high and the pump drive shaft sloppy in the housing bore.  I pulled out my old, 300,000 mile cover and set the end clearance to .002.  The side clearance was still under .002 with a few scratches.  I fired it back up.  Same gears, same pump cover and regulator parts, stock bypass in place.  I replaced nothing but the front cover, removing the brand new and installing the original.  All other parts are the same as before.  85 PSI cold start, 20+  hot idle and 50+ hot going down the highway at 2400 RPM.  After several miles keeping up with traffic at 3200 RPM and then stopping at the bottom of the off ramp, I still have a bit over 20.  With the brand new cover, the pressure would drop to 5 or so.

Poor choice of words on my part. Sorry about that, Steve. I didn't mean to make it sound like you were saying to half @$$ it. I also spaced the "side" clearance. I get asked about the end clearance so often, I glazed right over the "side" clearance part. Missing details like these is obviously why I am not good at building engines! HAHAHAHA!!!

OK, copy that. I would love to be able to run 10W40 with >15 pounds of pressure in gear, at operating temp. I don't think I have measured gear to housing side clearance since the first rebuild and even then, it was on a different timing cover. I will add this to my list of "Next checks". I pretty much always run dinosaur blood in this rig. I planned to change the oil around an hour of run time or 100 miles, hopefully after the rings have re-seated. Your car sounds awesome. Although 6kRPM probably was nerve wracking, I bet it sounded wicked to everyone else around you! 

I did not. When I re-assembled, I rotated the crank and spun the pump at various positions and it "seemed" like it wasn't that bad but now I am second guessing myself. Especially since I did not video it and (from my other thread):

69 ambassador 390 wrote: You probably have a lifter that was put together with the metering disc. upside down.  The peaks should go down with the flat side toward the base of the pushrod seat.  I have to take all our lifters apart and check, because about 20% are not correct.  The lifter will still function, but it will pass excessive oil if the disc is wrong.  Gott'a love the quality of new parts!

Not sure of my 2000RPM hot pressure. I have not brought it back up to Operating temp. I only really focused on cold and hot idle pressure. 

***************************

I had a few mins to tinker the other day so I decided verify my timing again. I hooked everything up to verify my dizzy is at 0 (computer controls my timing). It was. As I was putting the timing light away, I noticed the delay knob on my timing light was not at 0 (it was at about 15).  I never use that knob because I tune my timing on my laptop so I rarely pay attention to it. 

I'ma stupid@$$! I set it to 0, rechecked my timing, and, sure enough, I was 15 degrees advanced. That means when my computer was commanding 20 degrees, it was getting 35! When it was commanding 32, it was getting 47! 

Took it for another really short spin and it ran much better. No coughing, spitting, tons more power, etc. Imagine that! I did not bring it up to operating temp this time. 

I also noticed the wet spot that used to reside under the freeze plug is not there. Checked my water level and it is still full. Hm. Maybe it plugged itself?

I hope to open the bypass channel either later today or tomorrow. 

Reason I asked about the lifters is that was one of the first things you mentioned in this thread, #4's gushing oil. I saw you mentioned it again in another thread, or maybe it was in the tail end of this one. I would have replaced those lifters, just for peace of mind, for what they cost. Maybe that's enough to cause your low pressure, maybe not.

I am more worried about low oil pressure at say 2000 rpm hot, than I am 10 psi at hot idle. But that's just me, it could be low all across the board & that isn't ideal.

You would have noticed real bad lifter clearance on one lifter when installing the lifter. One lifter with excess clearance, unless it bleeds full flow i.e. the groove is out of the block, will not drop pressure more then 1 or 2 PSI.

Go with the 10-40 if you want, but definitely look at your pressure regulator.

On the pressure regulator, pull the plunger and put it in backwards to ensure it has free, full travel to the bottom. There have been some newer replacements that are larger OD then factory original that will hang open.