1931 Series 80, broken fuel pump

[drovak]

Hi all, I just became the proud new caretaker of a 1931 8-86. It would not start reliably, which turned out to be a bad electric fuel pump that the previous owner added. I wondered why the mechanical fuel pump was bypassed: well, it turns out the arm is broken, and I also noticed someone brazed onto the end of the pushrod for some unknown reason. 

 

The pushrod measures 8 11/32 in; does anyone have a measurement for what the proper length should be?

 

Here's some pushrod images. The brazed end was sticking out of the block, actuating the arm.

 

I assume the brazed end was an attempt to repair a worn end? Could the potentially extra length from the brazed portion have resulted in a broken arm?

 

The end that rides against the cam seems okay.

 

When I got the car, it came with both a fuel pump and carburetor rebuild kit. Within the fuel pump rebuild kit, I noticed that the main fuel pump gasket supplied don't fit. This was the closest fitting one, but you can see a large area of the mating surface is left uncovered. Any idea? I have since cut a new gasket, but was surprised to find that this one did not fit. When I removed the fuel pump for the first time, I found someone used a blue gasket maker compound prior.

 

 

The fuel pump is stamped Model B, 5751, so I believe this is the correct one for my car, from what I've read.

 

The bottom cover was highly warped, and even with a thick cork gasket, would not seal all of the way. I carefully lapped it, removing just enough material to get the cork gasket to seal.

 

Now for the real reason for the post: the broken arm. This part is stamped with 543, and I think I can make out a 1 on the other piece. Does 5431 match up with the AC part number? I can't seem to find it when searching around...

 

 

 

The rest of the broken arm:

 

The broken bits put back together.

 

How do I properly remove the pin going through the fuel pump body holding the rest of the arm in place? The last thing I want to do is damage the fragile pot metal, obviously.

 

Also, is there a chance the original arm can be repaired, presumably through welding or brazing? Or should I find a replacement or have a machinist make one?

 

Should I watch out for something in particular if I get someone to make one? Any problem machining one out of solid stock versus laminating it?

 

Any advice would be greatly appreciated. It will be nice to get the electric fuel pump out from the engine compartment!

[Robert Engle]

series 40. If I read my parts manual correctly, you can use any 31 60,80,90 fuel pump.  The rocker arm from 1930 40,50,60 will fit your 31 fuel pump.  The pump operating rod is unique to to 31 80 and 90 series.

 

Bob Engle

 

 

[edinmass]

Parker’s Packards in Massachusetts owns the largest fuel pump rebuild company in the country. Look them up on google and give him a call. Not sure what name he runs his fuel pump business, but he has several full time guys only doing fuel pumps.........he is a great guy........give him a ring. Tell him “Pierce Arrow Ed” sent you.

Edited November 3, 2020 by edinmass (see edit history)

[Dave39MD]

855751 (5751) is the correct pump for 31 60, 80, and 90 series so you have the right pump. The rocker arm for that pump is 1521745 and also fits 35-36 Auburn, Cadillac 32-37, Federal Truck 40,  IHC 32-34, 39-40 and the 30 Buicks Bob mentions above. My catalog did not give specific models on the arm fitment.

 

Good luck and please post if you get the measurement for the push rod-I am also dealing with that issue.

 

Dave

[raydurr]

I do not recommend attempting to rebuild your own fuel pump.The first reason is the scarcity of the pump and parts. There is a fair amount of expertise in rebuilding these correctly without causing damage. Most of the larger rebuilders have some spare parts that may work to replace your broken or worn parts. Pushrod length is critical to the life of your fuel pump. Excessive slack can produce a hammer effect which can damage the fuel pump parts and the engines camshaft. Surely someone reading has a engine with the correct pushrod length that could be measured.

[Mark Shaw]

• I just bought a new fuel pump for my Model 31-67 Buick here: https://www.then-now-auto.com/
• It came without the push rod.  So now I am trying to find the right length for my car. 
• I believe the end of the rods were braised to eliminate wear on the cam.  
• Braised end can also be renewed to compensate for wear over time.

[DonMicheletti]

It has been a long time, but I remember the pushrod on my -'31 8-67 ends being plain. I also expect they were hardened.  The brass on the ends would wear quickly I expect.

[Mark Shaw]

11 minutes ago, DonMicheletti said:

It has been a long time, but I remember the pushrod on my -'31 8-67 ends being plain. I also expect they were hardened.  The brass on the ends would wear quickly I expect.

Don,  I got this info from the gent from Then & Now who mentioned that several cars had push rods with ends like this....

[DonMicheletti]

This was in 1960 and my car was an unmolested original. But it WAS a long time ago when I restored the car