Oil pump drive gear backlash

Hello,

I noticed upon disassembly the oil pump drive gear had more backlash than I expected.

Going together now with a new cam and drive gear and it is the same.

Moving the cam fore/aft in the block (upper timing gear loose) does not tighten it up.

I ground the step off the base of the old gear to see if dropping it down would tighten it up. Same, no difference.

Bushing in block does not seem worn, no excessive play against shaft.

Here's a video with current parts and pic of wear patterns of old parts. Not sure how I could even improve this but something to chase or is this how they all are?

Thank you.

https://www.youtube.com/watch?v=fbRHukeqEUY&feature=youtu.be

Make sure the intermediate shaft isn't bottoming out in the oilpump.

OTH, the oilpump is always causing a constant drag on the intermediate shaft, so the backlash is always taken up by this in a running engine.

You most likely need to stop the upper movement in the dist.. that will reduce the dist turning.. I use a
collar on the dist shaft.. that will stabilize the turning and lift in the dist

Looks like that intermediate shaft gear needs to be replaced. In a lot of cases, the tang in the distributor is typically too short to hold the intermediate shaft at the correct distance off the block bushing. This can allow the gear to lift up and down excessively while the motor is accelerated and decelerated, which can cause excessive wear to the gears. My bronze gears would barely make it to 1500 miles until I discovered the excessive play.

One easy fix is to install a collar on the bottom of the distributor shaft that rides on the upper sleeve of the intermediate shaft, just above the drive tang. You will need to adjust it's position on the distributor shaft to allow clearance for the oil to fit between the bottom of the intermediate shaft gear and the block bushing. You can even use a feeler gauge if your intake and/or valley pan are off depending if big block or small block..

Make sure you have the right length oil shaft. There are 3 different sizes based on which oil pump you're using.

There's no oil pump on the engine right now. The shaft in the video is new, photos are of the old one.

Thanks guys.

I thought I remembered a oil groove in the block bushing??

Joe

I actually was just looking at mine this weekend. My milodon intermediate gear was run without a stop collar for a bit and is pretty worn. I had a good OEM one that I put in and my backlash is similar to yours. It was much worse with the worn gear.

Even with the stop collar my timing seems to jump around about 2 degrees, and I wonder if that backlash has to do with it. As mentioned I would think the drag from the oil pump would keep this loaded in one direction.

Hmm, interesting. You gave me the idea to check the original engine from my car.

There was less play, probably half.

Pulled that original shaft out and tried it in the current engine, same play as the new aftermarket shaft.

So, either newer cams have the gear cut differently (as it's the same with both I have) or the hole in the block for the intermediate shaft is too far away from the cam.

Could probably have an offset bushing made but now how does the shaft align with the oil pump.

I hope the folks here are able to track down and fix their problem.

But this whole thread shows why I want to use an external belt-driven oil pump.

dist tang to intergear fit can make the timing jump around. with everything (dist/intergear/pump) buttoned up, lightly move the rotor back & forth & see how much slop you have and always have the pump installed before the intergear install to insure a dead on hex alignment. A person might add some material (weld?) to the dist lower tang for a tighter fit. a sloppy tchain will also make the timing jump around.