I’ve checked it with another oil pump rod does not seem to be stripped but will check again today. I start getting mad and it’s time for me to stop messing with stuff I have a tendency to break stuff.Iv ran the engine with the currant set up for that last six months no problem and I used the efi one to prime it prior to running it the last six months. Only thing changed was oil pump.

 

After putting a manual pressure gauge on it while using drill it will go up to 20 psi. Then it will fluctuate and bleed off then after a few seconds go back up. May be the power pro oil pump is bad was given a brand new in box clevite oil pump guess going to try it. Thanks for all the help and trouble shooting

 

Forgive this question, but I don't know your engine. Does it have hydraulic lifters? If no, ignore this post.

If yes...
You say it "knocks" after starting it quiets down quickly. Do you mean there is valve noise? Does it knock if restarted after only a few minutes or does the knock only reappear the next day or week? I ask because if it only happens when the truck sits, I would consider a leaky lifter.

 

All engines available in these year trucks had hydraulic lifters.

 

It is my understanding that the only difference between the two, long "EFI" and the short "carb" distributors is that the long one was designed so you could easily engage the pump shaft (rod) before the drive gear engages the cam gear. Before these came out, you had to engage both gear and shaft at the same time. That often meant a extra stab or two as would have to slightly rotate the pump shaft until all was lined up.

 

Wow, Thanks for the walk down memory lane. That took me back to 1974 or so helping a buddy work on his 68 Fairlane at the Auto Hobby Shop at Pease, AFB NH I remember having a small issue do that.

 

That was one reason, another reason was more engagement to help reduce the likelihood of the oil pump drive shaft twisting. The shafts were the weak point on the stock engines and why many strongly recommend upgrading to ARP`s harden drive shaft. This is where the problem arises cause many people run the harden drive shaft which is thicker in the middle and a long snout EFI distributor wont be able to slide down far enough and it will not fully seat. This requires the cutting of the distributor to shorten the length or to find a harden shaft that is not a thick round dowel in the middle.

I dont think his problem is lack of engagement with the shaft I think he has an oil pump issue and thinks the shaft is not engaging cause there is no way the shaft wouldnt engage if it is engaging with the camshaft itself. If he attempted to use a 302 distributor I think it wouldnt even engage the camshaft and fully seat.

 

He said one was a half inch longer I thought?
Thatis whyI said to put the 2 dist. side by side and line up the bases.
I bet the short one is the one he is having an issues with.
Then measure each dist. from base to end of shaft then measure the motor from where the dist. base sits to the shaft and what do you come up with?
Dave ----

 

A 1/4" diameter dowel would work well for this. Remove the drive shaft and slide the dowel down into the socket on the oil pump. Mark the dowel even with the top of the block, where the distributor flange gets clamped down. Call this dimension A.

With the distributor on your workbench, measure from the flange to the end of the shaft. Then subtract the depth of the hollow recess in the end of the shaft. Call this dimension B.

Subtract B from A. Subtract another 1/8" or so to allow a little end play. That's how long the shaft should be, regardless of what pump/distributor combo you have.

If the shaft you've been using is close, that tells us the oil pump is being properly driven. I support the theory in post #12 that you're seeing oil pressure when driven by a drill because it's spinning faster. What's the rated RPM on your drill? With the engine running at idle, the pump is only spinning around 375 RPM.

 

I dont know about your motors but all mine if is in good shape show oil PSI at idle.
Heck you do an oil change first start is at idle to see if the oil PSI comes up then look for leaks.
Karl, you may not be wrong but you are not right with no oil PSI showing at idle

It is strange that if it is spinning the pump it is not show oil PSI (here we go) are you using the factory gauge or aftermarket?
Dave ----

 

Sorry took so long to answer been raining so could not work on it. Iv got both the gauges but got it figured out the spot on the oil pump for the shaft is deeper. I guess a factory defect or somthing got another pump to put on it just got to wait till rain clears out again

 

Nobody said a engine in good shape would not have oil pressure at idle. The op said he replaced a oil pump because He had no oil pressure at idle, after replacing pump he still had no oil pressure unless He spins the pump with a drill. My point was maybe he was spinning it much faster with the drill than the motor was. He said He thinks He found the problem, lets hope it is that and not worn out bearings.

 

Blasphemy!

I should have elaborated on my convoluted hunch. First, I suggested calculating the required shaft length to make sure the pump is actually being properly driven. Rather than trying to figure out if pump X and distributor Y are compatible, just calculate how long the driveshaft should be for that particular combination. If too short and not properly engaging the pump, that's a problem in dire need of correction. You'd have zero oil pressure at all times, no matter the engine RPM. But due to my amazing psychic powers, I don't think the driveshaft is really the issue. I think there's something wrong in the oil pressurization system (more in a minute), but it's only apparent when the pump is turning slowly. The fact that the low/nonexistant pressure is only present with the driveshaft installed? The seemingly mismatched driveshaft is a red herring, not the root cause at all.

Let's say at idle, the oil pump is spinning at approximately 375 RPM, at half crankshaft speed (750 RPM). But when driven by a drill, the oil pump is spinning at 1000 RPM or something in that range. (That's the same as revving the engine up to 2000 RPM.) That's almost three times as fast, with a corresponding increase in volume. Maybe the pump itself is within specs, but rod and main bearing clearances are excessive. Any pressurized oil is spilling out and normal pressure can't be reached when volume is low. Or maybe the pump is bad, or the pressure relief valve is opening too soon. Whatever fault is present, increasing the pump RPM overcomes it to some extent and you get some pressure. But slow the pump back down to 375 RPM and pressure falls off a cliff.

Confusion has set in, in my over-inflated opinion. It's like comparing apples and oranges to judge pump performance at such different RPMs. For a valid comparison, you'd have to slow the drill down to 375 RPM, to simulate the speed at which it's driven at idle.

How did you want to work out the logistics of apologizing for even insinuating I was not right? A public announcement? An engraved plaque, preferably chiseled in marble? A full-page ad in every major newspaper? A TV ad during the Superbowl? Skywriting? I'm flexible...

 

I thought he said after replacing the oil pump the motor did not have pressure I dont think he said it did not have pressure before the pump change or why he even wanted to change it ....... but I could be wrong and not going to re-read from the start.

As for spinning the pump faster with the drill than the motor maybe but if that was the case the motor was junk.
If any motor did not have oil psi at idle it would kill the bearings, what was left of them, in no time and the motor was junk.

It sounds like he found the issue being the pump where the shaft fits into was cut too deep making the shaft to short if I under stand it.
I still dont get why 1 dist. (priming) worked and the other did not?
Dave ----
Dave ----