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Let's chat about oil pump drives for Big Blocks

Kern Dog

Life is full of turns. Build your car to handle.
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I'm getting ready to start reassembly of the 440/495 for the Charger. The machinist should be done soon so with this free time, I'm gathering parts.
Oil pump drives......

251 R.JPG


The one on the far left was the one I pulled from the engine. Where it rides on the bronze bushing, it was scored a bit. Look close, you might see them.
252 R.JPG


I took some crocus cloth and took some of the ridges out but I can still feel some there. With the bronze bushing up under the gear, there is some slop, indicating excessive wear.

253 R.JPG




The second one is a low mile used one that I replaced when I changed cams some time ago. It has virtually no slop when I slide the bronze bushing over it.

The last two look to be original OEM shafts.

The first two have the tapered edge where it turns to the 6 point hex.

254 R.JPG


I'm going back to a standard volume oil pump this time. I have used high volume pumps on every big block but was told that the stock oiling system is more than adequate and that high volume wasn't necessary for the type of driving that I'll be doing....No extended high rpm operation, no dedicated drag racing, moderate spring pressure-flat tappet cam etc.

Buying new isn't a problem....

dcc-3571071_ml.jpg

Mopar Performance Oil Pump Driveshaft and Distributor Gear Sets P3571071

Oil Pump Driveshaft, Distributor Gear, Flat Tappet Cam, Chrysler, Dodge, Plymouth, Big Block/Hemi, Each
Part Number: DCC-P3571071
5.0 out of 5 stars ( 4 )
In Stock (more than 10 available)

Estimated Ship Date: Today

  • Free Shipping
$100.99

BUT if I don't have to spend the money, I'd rather not.
I've read that the drive with the PIN in the gear is the most desirable but how crucial is that? I've never had one of these fail.
 
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i have run bb for a lot of years. back when drives were cheap, we bought the pinned one. then they went up. use stock one and pin it yourself. we have done that also. never had a problem with home pinned unit.
 
use the original that is what I would do
 
I would run the second from left, with a high volume pump. With a standard pump, I would run any of them. (I'd mic all four at the bushing area).
I might pay $100 for a bronze gear for a billet roller cam, sure wouldn't pay that for a stocker.
 
Run the 2nd one. Pinning it is not a bad idea.


Too bad on that scored shaft. Looks like it may be a MP hardened part. Possibly the intermediate bushing wasn't installed correctly and closed up when pressed in, making it too tight on the shaft.

An install example on a SB.....
 
From what I've read, the tapered units are supposed to be stronger at that area, less likely to shear off. I'm sure you already know to pick the gear portion depending on what you end up with for a cam. The Melonized[ no, not treated in melon juice. ha!] is supposed to be really good and the composite ones too. The drive bushing needs to be knocked in of course but after its in, there is a special tool to use to get it set and ready for use. I believe it expands in the hole after its driven in. Consult your FSM for that procedure.
 
This is a pin guage - available at most machine tool suppliers. It will do what the fancy factory tool does. Just tap it through the bushing after installing it and it will seat the bushing to the proper diameter and clearance.

Dist bushing burnisher.JPG
 
As long as there are no burrs on it I wouldn't hesitate to reuse the first shaft but if you already have it, use the second one.
 
I took the first shaft to my machinist. He thought there was too much clearance between the shaft and the bushing.
 
The MP shafts are NOT hardened & I presume the Isky/Mancini/Hughes are also not.
You have to go back to the history of these shafts. The tapered end at the hex is a good idea because it eliminates the sharp edge, a stress point, in the original. The shaft as I recall was made of 4340 steel which is hard.....but not hardened. The std shaft was made of hardened steel, almost tool steel, which had good wear characteristics, but brittle & broke easily if twisted.
The 4340 was more forgiving with twisting from the pump load.
I was using the MP drives when they first appeared & noticed the shaft wore quite quickly with the bronze bush. That is because bronze is a hard metal. I only use the MP shafts now [ used one last year in a 440 ] with an alum bush, which are hard to find. I have a couple I have collected over the decades, but note sure which engines used them. The MP shaft will not wear with the alum bush, nor will the bush. You do not want wear in this area because it can affect ign timing. Ch should have sold an alum bush WITH the shaft.
 
Though I've seen the shafts wear some it's never been an issue. The tapered ends seldom break off. That being said if the end breaks it's usually cause there was debris in the pump.
Doug
 
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