Timing and distributor installation on 99 Jimmy 4.3

BrentFields · March 12, 2007

I did and engine swap on a buddies '99 GMC Jimmy recently. When Installing the the distibutor I brought the crank around until the mark on the balancer lined up with the notch on the timing cover.

I then marked the distributor case to line up with the #1 spark plug wire. I dropped the distributor into the block with the rotor lined up to the #1 mark.

When I tried to start it, it seemed to be out of time and didn't want to fire.

I know (or at least I plugged something in that makes me believe) that there is a crank position sensor.

I would assume that since there isn't any room to turn this distibutor once it's installed that the ECM is controlling the timing.

I thought I might be 180 out, but when I pulled the distibutor and rotated it 180, my results were the same.

Is there something I'm missing? Are there any special tricks? This is a freebie job for the guy and I would like to be able to complete it without him having to take iot to a shop to get it started.

I think it's getting spark and fuel.

Tonight I'm going to rotate the engine around with my finger over the plug hole so that I know it's on the compression stroke, make sure it's TDC and then line up the rotor with number one again.

Maybe it will fire right up, but I would like to know if there's something I'm missing.

Everything is plugged back in.

Thanks

lab1508 · March 15, 2007

I am dealing with a similar situation. I am not sure what marks to line up to achieve TDC.

Any help would be appreciated!

Chris · March 15, 2007

maybe get a chiltons or haynes manual. when i changed the head on my tbird the crank had to be at 12 oclock and the cam at 5 oclock for everything to go right

BrentFields · March 16, 2007

maybe get a chiltons or haynes manual. when i changed the head on my tbird the crank had to be at 12 oclock and the cam at 5 oclock for everything to go right

We got it running after about the third try.

One of the guys had found a couple of forums that kind of contradicted each other, but we tried both ways.

The first problem was that for some reason GM decided to put two grooves on the balancer. I was alighning the first one that I saw. I went over to look at the old engine and realized that the 2nd one was actually TDC.

I then, pulled a plug and had one of the guys roll over the engine while I controted myself around to get a finger over the plug hole to make sure we were on the compression stroke.

When that was all done, here's where things get tricky and don't make sense. In normal circumstances, I would have lined up the rotor with the #1 plug. NOT ON THIS ONE!

Line it up with number 6! Why, I don't know! It fired right up and the idle smoothed right out. The worst part was getting the oil pump slot in the right orientation.

Hope this helps you other guys.

Thanks!