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Horsepower and Hops
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Discussion Starter #1
I have an older Melling pump that has uses a hex shaft instead of the standard slotted. It has a pickup on it that is sort of specific to my pan as well. I was sending a set of pistons to Line2Line to be coated and decided to get the pump gears coated as well and put it back in service. Well I got it back together,went to spin it with the shaft and noticed a lot of play. Looked inside the shaft and noticed there was a good amount of wear, didn't inspect it upon teardown. Apparently they only used them for a while and then went back to the standard, Melling said they haven't had any on the shelf for years. I was hoping one of you guys had one in good shape lying around that I could purchase before going to a whole new pump and pickup. Thank you
 

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never seen one like that on a chevy?? Sounds easy enough to make, if you can't find one, I'm in NC, if all else fails, mail it to me and I'll duplicate it, machine you one up. Mark- RPM Machine Co.
 

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Horsepower and Hops
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4,574 Posts
Discussion Starter #3
never seen one like that on a chevy?? Sounds easy enough to make, if you can't find one, I'm in NC, if all else fails, mail it to me and I'll duplicate it, machine you one up. Mark- RPM Machine Co.
Thanks for that offer Mark. If I cant locate one I will definitely get in touch with you. I'm in the Piedmont Triad area. Here's what the pump looks like.
 

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ok, easy enough, looks like 3/8 hex on the pump, I'll make sure I have that size internal broach tomorrow when I get to the shop, just in case!
 

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Horsepower and Hops
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Discussion Starter #5
ok, easy enough, looks like 3/8 hex on the pump, I'll make sure I have that size internal broach tomorrow when I get to the shop, just in case!
I believe it's 5/16", but I will take a measurement to make sure
 

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Horsepower and Hops
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4,574 Posts
Discussion Starter #6
It measures .340
 

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I kill parts
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I have one of those pumps as well in great shape, but don't have the shaft. - Had thought of finding a socket to fit it and modifying a stock shift to suit with a press fit and TIG the socket.
 

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Horsepower and Hops
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4,574 Posts
Discussion Starter #8
I have one of those pumps as well in great shape, but don't have the shaft. - Had thought of finding a socket to fit it and modifying a stock shift to suit with a press fit and TIG the socket.
I thought about that as well Jp, bug I think it would always be in the back of my mind. Had a Taurus in the shop the other day with a bad cam sync and it had a hex shaft. The length looked close and considered matching a slot in the end, but the hex was too small.
 

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I kill parts
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My thinking was that if I turned the drive side of the socket round and turned the shaft down to press fit them together, then tig'd it, it would surely be stronger than the distributor roll-pin that's driving it.
 

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Horsepower and Hops
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4,574 Posts
Discussion Starter #10
My thinking was that if I turned the drive side of the socket round and turned the shaft down to press fit them together, then tig'd it, it would surely be stronger than the distributor roll-pin that's driving it.
Yeah that would probably work good
 

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The hex type of drive for small block oil pumps was first introduced by Hoof Manufacturing Co, in the '80's and was later marketed by Melling as well. OP, your best bet it to have a complete one piece drive manufactured by someone like Mark.
 

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Horsepower and Hops
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Discussion Starter #12
The hex type of drive for small block oil pumps was first introduced by Hoof Manufacturing Co, in the '80's and was later marketed by Melling as well. OP, your best bet it to have a complete one piece drive manufactured by someone like Mark.
Interesting. Thanks Bill
 

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EFI/N2O JUNKIE
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Pretty sure my Titan pump came with that hex shaft setup. If I can find the pump I will let you know, or call them and ask.
 

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EFI/N2O JUNKIE
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Titan is the inverse of this; the pump is the socket side, the shaft is the male hex.
Ok, but at least my old brain kinda got something right! :)

I am sure a good machine shop can make what the OP needs.

I think you are right, my shaft looked like hex stock, when he needs the opposite, thus the mention of a broach up above.

I have watched this kind of stuff done, always amazed at what skilled people can do.
 

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Horsepower and Hops
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Discussion Starter #16
One more bump to the top just in case someone happens to have an original before I have one made.
 

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I seen this thread the other day and did not remember that I used the same pump years ago. I will look in my stash and see if I still have it.
 

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Horsepower and Hops
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4,574 Posts
Discussion Starter #18
I seen this thread the other day and did not remember that I used the same pump years ago. I will look in my stash and see if I still have it.
Thanks man
 

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Horsepower and Hops
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Discussion Starter #19
One last bump before ordering a pump
 
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