It seemed like a simple goal: Let's try and fine tune the timing. All I need is a screw driver and a timing light, how hard could it be?
Then, I looked online. The internet is an interesting thingy. You can find all sorts of information, both right and wrong and chances are, you won't be able to tell exactly what is right or wrong until you give it a try.
However, before trying much online, I just did the usual thing. I hooked up a tach, connected the timing light and fired it up. And of course, no timing BB shows up in the window. By the time I was done playing with it, I of course had no idea where I began or how to return it to where it was to begin with. To make things a bit more interesting, the timing light worked intermittently and then when it was working, it would flash normally and then throw in a burst of flashes just to confuse me.
Now, I had read online that it was easy to figure out which way to turn the distributor to advance or retard ignition timing. If revs go up, you are advancing the timing and if it goes down, you are retarding it. Problem is, if you go too far either way, it will slow down and obviously, from there, the opposite of each will both INCREASE revs! Thus making that piece of information somewhat useless. So, back to the interwebs I went. I needed to know exactly which direction to turn the distributor to advance or retard the ignition. In one thread where someone had asked that very question, nearly every other post contradicted the others! One would say CCW to advance, the next would say CW to advance. Amazing.
"Time it using the vacuum method" they said. A lot. Usually without ever telling what exactly the "vacuum method" is!
After hours of divining and separating out information, I decided to give the "vacuum method" a try. The questions that had to be resolved to get to this point were things like "Which way do you turn the distributor?", "Do you connect the vacuum gauge to the vacuum advance source or the windshield wiper source?" And another favorite:"Do you leave the vacuum advance hooked up or not?" And then there was, "Do you do it at idle or at 2000 rpm?".
In the end, I stuck the vacuum gauge to the manifold vacuum nipple, left the vacuum advance hooked up (discovered through trial and error that there was no vacuum there at idle) set my idle at about 500 rpm and watched the gauge. As far as I could tell, I was supposed to advance the dizzy until max vacuum was found and then back off 1".
That seemed like it should be easy enough. So, there I was with right at 20" on the gauge. Pretty good so far. Turned the distributor to advance the timing and the gauge changed exactly 0". Turned it the other way, same result. Only difference was that turning it too far either direction made the needle bounce around the 20 mark. Now, I had actually stayed home from church to deal with this as we had a truck club BBQ to attend and bringing the truck was kinda a necessity. So, with it becoming somewhat urgent to get this done, I set the dizzy where the needle was the least bouncy and tightened it down.
So, the wife and child got home from church and off we went to the BBQ and of course, there was pinging. I came prepared with a screw driver and made multiple stops to adjust the timing by retarding the timing, otherwise known as turning the distributor clockwise. The pinging seemed to slowly go away with each adjustment, except one, where it seemed to get worse. I kept turning the thing clockwise, mostly in small increments but it was kinda getting disturbing just how much I had moved it and yet still had pinging.
Today I drove the truck to work and once again, at work I retarded the timing and I have now MOSTLY gotten rid of the dreaded pinging but it is still there in high gear when applying throttle at higher road speeds.
At this point I feel as though the timing on this truck is darn near severely retarded.
