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Oil pump drive gear backlash
#2801524
07/26/20 09:38 PM
07/26/20 09:38 PM
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Joined: May 2019
Posts: 713 Lake Villa Il
INTMD8
OP
super stock
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OP
super stock
Joined: May 2019
Posts: 713
Lake Villa Il
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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
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Oil pump drive gear backlash
[Re: INTMD8]
#2801664
07/27/20 11:12 AM
07/27/20 11:12 AM
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Joined: Mar 2007
Posts: 3,285 West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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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..
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Oil pump drive gear backlash
[Re: second 70]
#2801684
07/27/20 11:42 AM
07/27/20 11:42 AM
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Joined: May 2019
Posts: 713 Lake Villa Il
INTMD8
OP
super stock
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OP
super stock
Joined: May 2019
Posts: 713
Lake Villa Il
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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.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Oil pump drive gear backlash
[Re: jlatessa]
#2801717
07/27/20 01:14 PM
07/27/20 01:14 PM
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Joined: Jun 2006
Posts: 5,163 CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,163
CT
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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.
Last edited by GTX MATT; 07/27/20 01:14 PM.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: Oil pump drive gear backlash
[Re: GTX MATT]
#2801841
07/27/20 07:08 PM
07/27/20 07:08 PM
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Joined: May 2019
Posts: 713 Lake Villa Il
INTMD8
OP
super stock
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OP
super stock
Joined: May 2019
Posts: 713
Lake Villa Il
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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.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Oil pump drive gear backlash
[Re: hemienvy]
#2802123
07/28/20 12:50 PM
07/28/20 12:50 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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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.
live every 24 hour block of time like it's your last day on earth
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