Technical SBC bent fuel pump rod WTF

Yuppers, That is exactly how it happens. I've fixed a couple and may be guilty of bending one. The ones I fixed had the original pushrods in them and got bent when a pump was being replaced, In one case the lever on the pump was all bent to hell on the new pump. Then it was towed to me to be fixed.

 

At least they're cheap

 

That’s kinda what I figured, something wrong on the fuel pump end. Ran a bore scope up there and the cam looks good.
Took the fuel pump under the scope, took it apart and there does seem to be something screwy in there but I can’t determine what or why. The arm isn’t actuating the internal diaphragm. It’s a pro cam pump.
Top half works when apart but not when bolted together.

 

This is a common problem, check that bolt. It is used to hold the rod up during fuel pump installation then taken out and a short one put in so oil does not leak out of the hole.

Pat

 

It can’t bend between the cam and block…..not enough room.

 

I was given a SBC fuel pump pushrod a few years back that was longer than stock. It was made for an aftermarket block and I didn’t realize it. My motor fired up and ran great for about an hour. After break in i revved the motor more aggressively and the longer pushrod broke the lever out of the fuel pump.

 

I absolutely agree with the above statement. I will also add that if the problem was between the cam and the block, the bend between the fuel pump and the block wouldn't have happened.

 

I found a bent one a few years ago, didn't want to go in the block. Pulled it out and put it against a straightedge, long way from straight. Not sure where it came from or how it got that way.

Devin

 

I've actually seen this a couple of times. Each time, the fuel pump arm was involved. The first on the arm on the pump itself was bent, and it allowed the rod to walk off the arm and both bent. That motor ran about a 1/2 hour before it quit.

The second one involved an incorrect installation of the pump. The rod apparently did not "stay" up during the install, and the pump was installed with the arm against the side of the rod. As the bolts were tightened, the bolt tightening forced the pump arm against the rod and bent the rod. With that one, the motor didn't start at all. A new straight push rod solved that problem.

I suppose it was possible the first one was caused by the same thing as the second one, but beside bending the original push rod, it also bent the pump arm. That guy realized the bent arm as well and had returned it to the parts store and someone there put it back on the shelf and sold it at a later date.

 

I believe that a SBC rod is 5 3/4" long......hmmmm

 

If the rod dropped during installation and got bent, it wouldn't be against the cam so it wouldn't give you any 'feel' or resistance.

 

Did you hit that pushrod with a file to see if it's hardened? No way it can be. If it was hard and something was afoul, in my opinion it would destroy the pump before the pushrod.

 

If the rod was bent on the end next to the pump a bolt in the front of the engine was not the issue. If it was bent on the other end how did you get it out?

 

never seen a bent rod like that

 

There are several different SBC fuel pumps and applicable push rods, got to get the rod that goes with your fuel pump.

 

I believe all SBC and even the BBC pushrods are 1/2” x 5 3/4”, if you found a longer one it’s for use in an aftermarket tall deck small or big block with a raised cam tunnel.
And the OEM rods are hardened, and tough as nails.

 

Didn’t I start this off with “it wasn’t the bolt”
Let’s check,,,, yep I did.

The rod needed one hell of few smacks with BFH to get it to move, the hammer blows made some dents, So it’s harder than frozen ****er but I did not put a file to it. It was the correct length.
Got a new rod and a new pump & everything seems fine now.
The forensics in an earlier post leads to something wrong with the fuel pump, I can’t tell exactly what yet ( no time) besides the internal mechanism isn’t moving, thus locking up the arm at 1/4 stroke. The arm moves against the external return spring but not enough.
I could see the rod breaking the itty bitty roll pin holding the pump arm, I could see the pump arm breaking or bending, I still can’t come up with how the rod bent but it don’t really matter I guess.

 

That’s what I thought (hardened) the one I have the broke, was like a snap. I could put it back together and by eye couldn’t detect any bend.

 

Fast cure , install a Ford engine .

All joking aside , that rod is case hardened , I suppose . I have never seen one bend , if it was running against a cast camshaft I would almost suspect damage to the lobe also . Just my 2 cents .

If you changed to a new push rod and pump , all is well , seems as if you cured what was bending the first one .

 

They never bend on the cam end. Why they got bent on the pump end is as several of us described. Improper installation, damaged pump arm (could have been improper installation. third is someone ran a long bolt into the front motor mount hole and tightened it down until the rod bent but the bolt didn't bottom out. When you screw a longer bolt in to hold the shaft you usually only have to screw it in with your fingers.

One that I know was bent with a bolt, the guy ran a too long of bolt that was threaded up to the nut in with a half inch impact. That was done by a guy who claimed to be a mechanic who was on about his second and last day working for a buddy of mine. My buddy showed me the rod and the bolt.
The other one was towed into the high school autoshop that I was then a student in. It was one of those "we put on a new fuel pump, we put on a different carb, we did this and we did that but it won't stay running" rigs. in the mid 60's if someone in town couldn't figure out why their car didn't work or if the independent shops didn't want to work on it we ended up with it at the high school auto shop. Palmer said to pour some gas in the float bowl vent and see if it will start and run. Yuppers, it fired up and ran for about 30 or so seconds but quit. Not trusting the gas gauge we put some gas in it and tried again, nothing, Mr Palmer says to pull the fuel pump and check it. Sure enough they had managed to bend the pushrod enough for it to hang up in the block and bend the pump arm. The pushrod doesn't have to bend much to hang up. That one didn't have a dramatic bend, it just wasn't straight. The arm had the hell bent out of it though. We figured that the guys who put the pump on just forced things rather than figure out how to do it right.

 

I think it's the way it was installed, unevenly. Maybe the cam lobe wasn't rolled to the low, the bolts used to draw it in place were tightend one side then the other, and that uneven force leveraged the pump lever off to the side.