New Hampshire CMP Barn 2011- 2012 HUP Overhaul

[hrpearce]

Originally Posted by Bob Carriere

So if I am spinning the oil pump with a 3000 rpm drill...... allow for some 30% reduction for oil drag....... the oil pump is turning the equivalent of 4000+ engine speed.... am I correct...? that could explain my 42 pounds of oil pressure.

???????? Bob

Correct Bob you were probably between 4 and 5,000 engine revs depending on the torque of your drill.

[Phil Waterman]

Hi All

Well I took the process of checking the Oil Pressure and Flow to the next level. First I confirmed that the distributor shaft and hence the oil pump drive makes one revolution for each revolution of the crankshaft. Then I brought the engine up to operating temperature which is 170 F with ambient air temperature of 75-80F this is with a 180F thermostat.

I shot video of the engine oil flow in the valve gallery at various RPM levels. In the photos below you can see the differences. Then I changed the oil and did a new set of videos. Which is when I noticed what I think is the problem excessive oil flow from the rocker arms. The shafts are new but the individual rockers are the originals.

It was looking at the video and stopping it and going back and forth that really clued me into what it the problem of. Take a look at the Video http://canadianmilitarypattern.com/R...stem%20DSL.wmv

Still looking for input but I think it is worth putting the engine in the truck, road test it.

Cheers Phil

[Bob Carriere]

Granted there seems to be a large amount of oil flow on the rockers....


..... but let's go back to the beginning of the oiling system.....

The rockers are the lasts step in the oiling process...... first the crank, camshaft and then to the top of the engine where it eventually get dumped in the return channels/holes in the head back to the crank case.

If all the other bearing clearances are tight or at least according to specs. the oil pressure doesn't really start to fall until it reaches the loose rockers...

.... the oil pressure sensor is located early in the oil galleries... then why would it be so drastically affected by a leak further down into the system....

Is there anyway that you can reduce the flow to the rockers to confirm that the looseness of the rockers are in fact affecting the overall oil pressure??? some kind of temporary restriction inside the line...?

If you can confirm that the rockers are at fault it would be relatively easy at this stage to correct before installing into the truck.....

Now some rockers can be bored out and brass sleeves installed... not sure if that is feasible on the 216..... so rocker tubes are new and rockers as is.... it would not be too complicated to measure for clearance.....

When you got your NOS head did it have the full valve train or was it bare....?

If you need rockers I may be able to help you out...... how similar are they between 216 vs 235 vs 261...... 235 and 261 are usually interchangeable but not sure if low pressure 235 would interchange with high pressure 235 rockers

Keep us posted...

Bob

[Phil Waterman]

Hi Bob

Good idea about isolating the rocker arm assembly to see what it does to the oil pressure. Think it can be done fairly easy, if that makes the pressure jump up then that is fairly easy to rectify.

Couple of choices, as you suggested, I've got the bushings to bore and bushing the rocker individual arms, but a complete new replacement is $250. Plus I've got another used assembly that I think is good condition.

I'll try isolating the supply today, if that identifies the problem then great, if not then I think the next step will be to drop the oil pump, or brink the 216 that came out when I swapped over to the 261. I kept it complete so it would be a half days work to get it all set up again.

Don't think there is a suction leak because there doesn't seem to be any air bubbles showing in the oil. Just the normal air bubbles as the last of the air is pushed out of the oil filter even with filling the filter body with 2 quarts of oil before putting the cover on.

By the way I recovered all the oil from the oil change into clear bottles and there doesn't to be any large chunks of stuff.

Cheers Phil

[Phil Waterman]

I'm now to the point in the reassembly of the HUP that the wiring harness, fuel lines, break lines have been all installed. One small weeper leak in the brake system of course it is the big fitting on the master cylinder which should seal OK just needs to be tightened but of course will mean bleeding the entire brake system again.

In painting small parts to reinstall I came across one brass marker light I'd heard that these existed but this is the first one that I actually seen.
HUP May 2012- 007.jpgHUP May 2012- 008.jpg

Cheers Phil

[Bob Carriere]

...... you should save that brass marker light a wall mounted plaque/trophy....

Reminds me of the lower rear axle shock absorber bracket, the one that bolts on the diff. cover....... Rob found one made of cast brass....even had proper GM part numbers on it....... go figure !!!

Curious to hear what you find about the oil flow when a restriction is applied to the oil flow of the rockers.

Bob

[Phil Waterman]

Hi Bob

Well it's not the rocker arm assembly spent an hour this morning testing the theory that it was excessive flow from the individual rocker arms that was causing the low oil flow from the rocker arm bypass or over flow.

After bring the engine up to temperature and basically stabilize at 1500 RPM here are the results the end result was with the oil line to the rocker assembly disconnected and blocked there was no difference in oil pressure. Also posted a really dull video http://canadianmilitarypattern.com/R...%20Flow%20.wmv

So spent the rest of the day working on reassembly of the HUP pretty much decided that I'm going to concentrate on getting the HUP completely reassembled. Tomorrow I plan to bring the other 216 engine down from the loft and set it up to run. That way I'll should be able to get the HUP on the road for the 25 Anniversary Weare Rally end of July.

Should take me about 3 hours to set the other engine up and test it. I'll come back to this engine once everything else is done.

Cheers Phil