1/8" Timing Bump
 

Hi Guys,

I have a question for ya regarding the timing bump. I am in the process of remounting my pump back on the truck and when the keyway lines up with the timing gear, the pump is at that 1/8" or so bump point, instead of at the stock timing spot. Any ideas? I was thinking that the pump must be mounted to the gear and then you turn the pump to match the 1/8" bump spot but maybe I am wrong?

That's because you didn't lock the pump shaft before removal. You can mount it like is and then pull the pump back to stick timing mark or leave as is.

What happened is the springs were under tension because you were on the can lobe so when you pulled the pump the springs unloaded their tension and turned the shaft a little bit.

I did lock that shaft when I removed it and diassembled it. I unlocked it then for some reason and then locked it after reassembly. It was locked to the point where the keyway in the shaft lined up directly with the timing mark on the front of the pump.

You need to set the pump to spec at TDC as found by the timing pin, using a dial indicator in the hole in the center of the output distributor on the back of the pump. Then you mark the pump. The 1/8 inch move is then made from there.

Normally, when a pump is set up, it is dialed in on the bench and locked down. The timing mark is buffed off at that time. You put it in with the timing pin engaged, and put a new mark in it with a cold chisel.

When you're messing with em, or moving them from truck to truck, you have to dial it in on the truck.

Im also in the process. That mark at the front desnt seem to correspond to tdc. When the ip is mounted, that mark is at the 6o'clock position. At tdc the keyway is suppossed to be at 5:30, according to the video.

I'm no expert by any means, but I'd use the dial indicator procedure to define TDC lock down for the pump.