So, I've had my '95 2 door for about 2 months and have slowly been taking care of different things. A few that obviously needed to be done, as well as others, so that I'd knew they'd been done and when. One of those was verifing that the timing was correct. A simple thing....yet not always so simple as there are a number of differences with these trucks, even among the 2nd gen. For instance, my timing bypass connector was not under the passenger side carpet on the firewall as I have read on this site, as well others. The GM factory manual shows the connector as a single wire loop coming out the computer wiring harness near the computer, and that's right where it was. On mine at least, the computer has to be dropped down to access the connector.(see pics) Anyway, I thought maybe others, with the same set up as mine, could benefit from a few photos. My '95 has CPI, and an OBD 1 (1.5) system with the computer under the passenger side dash. Also, it has the plastic timing cover and does not use a metal timing tab. It has a cast in protrusion with a single timing mark, or actually more of a v groove. There are 2 different marks on the balancer not too far apart. Remembering that the engine rotates clockwise when viewed from the front, the correct mark is the most "clockwise" one, or the first one that comes around as you crank the engine over. Seeing the marks well enough to shine a timing light on them, seemed impossible with everything in place. Removing the intake plumbing between the air filter and the throttle body gave me a straight shot at the marks.(see pic) Just don't do it in the middle of a dust storm, or parked over a sand pit. Pulling in otherwise clean, unfiltered air for the length of time it takes to check the timing won't hurt a thing. I also put a little white paint on both the balancer mark and the mark on the timing cover to make them stand out a bit better. When you start the engine with the bypass connector unplugged, it won't idle as well as it normally does because it's operating with no ignition advance. In my case, my efforts were justified. Even though it seemed to run ok, the base timing was a few degrees after TDC, rather than at TDC. Loosening the distributor hold down bolt was a bit of a challange as well. The bolt on this engine has a 9/16" head, just like V-8, but no way would my V-8 distributor wrench work. Just not enough room. A chrome 9/16" swivel socket and an extension might work, but mine is MIA and my 9/16" impact swivel was too fat in the wrong place. Went to Auto Zone and got a distributor wrench that you turn with a 3/8" rachet and it worked well. (see pic) I needed to advance the timing a little so I had to rotate the distributor counterclockwise a tad. Of course, unless you're very lucky, you'll turn it a bit, check the timing with the timing light, and readjust as needed. When everything was buttoned back up, and I drove it, throttle response seemed a little better. Then again, maybe it's just in my head. It'll be interesting to see if there's any improvement in fuel mileage, but at least now I know it's right.
Here's the computer dropped down.

This is a close-up of the bypass connector wire (circled) still taped to the computer harness.
Here's the connector unplugged.
Intake plumbing removed and laid to the side.

Distributor wrench used.

 

That is the procedure for the OBD1 and I believe even the OBD1.5 setups. I can't tell from the picture, but your distributor has vertical wire terminals, correct?

 

Yes, that is correct.

 

I know this is an old thread, but I am having problems getting my distributor installed correctly. I just wanted to say this is the 1st one that addresses my particular vehicle. All the others I have seen cover the EDI dist and this one has the HEI dist (has the small rotor button) with vertical wires and the OBD 1.5.
The question I have deals with the 2 timing marks. If I am setting it for TDC do I use the 2nd cw mark on the balancer? If so, is there a timing mark on the engine for the 1st mark to be lined up at the same time as seems to be the case on other 4.3's? I hope I didn't confuse anyone with that last question.
Also, is the distributor cap set with the 1&6 plug towers toward the center of the engine or turned to one side?