Cadillac 346 Flat Head fuel pump question. . Spooky

[GoManGo1946]

Hey guys, I have a 46 60 special with a 346. I put the motor in a few months ago and was able to let the car run with no problems. I had run it for combined times of two hours of a few months just so I could work out the bugs. Was not drivable. One day it was at idle and just quit. I was not near it when it quit running. Fuel pump was dry. Rebuilt the fuel pump and put a hose on the pump and into a cup of gas. One pump and I was filling the bowl. Put it in the car and.....no fuel. On and off many times checking and rechecking and still no fuel. Look in the timing chain cover and the lobe looks ok and is not free spinning. Start looking at the arm  and it looks bent. Look in the timing chain cover again and there is no way the arm is touching the lobe. Here it was bent about 3/4" higher than where it should be and 5/8 inch back towards the engine. You can see rub marks where the lobe was rubbing the side of the fuel pump arm and marks on the timing chain cam gear. the arm was between the lobe and the cam timing gear.  Why did this happen ? I did bend it back and its fine now. Can it happen again?


Thanks

[Doug Houston]

Since bthe pump did work for a short time, it appears that the arm was bent slightly before it was installed on the engine. When it was running, the arm probably slipped down on the neck of the eccentric, and on the neck of the eccentric. If the pump had been mounted with the arm not riding on the eccentric, which has probably happened hundreds of times, there would never have been any pump action at all, and the engine would never have run at all.

There may be another theory to this, but this one seems to be the most likely scenario.

[Robert Schuman]

It is very easy to bend the fuel pump arm during installation of the pump, and that appears to be what happened to yours. The pump arm must be kept perpendicular to the camshaft while installing it, most easily done by getting two bolts at least an inch longer than stock. Use them to install the pump, tightening each on a little at a time to avoid cocking the pump. After fully seating the bolts, remove each one (ONE AT A TIME)and replace with the stock bolts.
If the pump is cocked during installation, the arm gets caught against one side of the cam and bent when the bolts are tightened. If it rides up on the cam, as yours probably did, it will work for a while. Eventually it dropped off of the cam, and stopped pumping. Straightening the arm, as you did, is the correct repair, as long as you don't crack it.

[GoManGo1946]

Thanks for the info guys.

[cadillac60]

Adam,

I read your topic on the problems you had with the bent arm on your fuel pump.  I have the same problem & would like to knopw the proceedeure you used tobend the arm back to its correct position?

Bruce Watson

[Bob Schuman]

Bruce,
I'm sorry, but it's been so many years ago that I don't remember how I bent the arm to get it straight. I don't recall that it was very hard to bend, though.
Bob Schuman, CLC#254

[cadillac60]

Bob,

Thanks for your quick reply

Bruce