I bought a $24 HF timing strobe light a week ago, and finally had 5 minutes to play with it this weekend. At two months shy of my 65th trip around this planet, I used a timing light for the first time. Go figure.
I quickly realized the face of my well marked crankshaft pulley was not visible as I pointed the strobe at it - I could only see a single line of paint at TDC on the OD of the pulley. My engine was warm and running so I studied the mark at idle, and as I revved the engine a bit, and as I held it at about 3k rpm based on my view of the dashboard tach. I then turned the engine off, and using a marking pen and a mirror I put a mark at 12, 25 and 30 degrees which I guessed would be helpful.
Upon restart, while at idle the 12 degree mark was aligned with the case split, so that’s my advance at idle…right? (Idle is at about 1100 to 1200 rpm - I don’t have a tach/dwell meter, just my dash tach.) The mark was pretty steady - it would jitter a little bit once in a while, maybe a degree or so, but I have no reference to know what is normal. I then slowly ramped up the revs a few times, then held it at 3k a few times and back to idle. During ramp up, I did notice occasional drop outs where the mark must have moved enough for me not to see it , I guess that means it either failed to fire occasionally? Faster ramps usually produced a bit more jitter, but nothing I would describe as wild, but again I have no reference. At 3k my 25 degree mark lined up with the split and I would describe the mark as being steady, but not perfectly so. I also noticed that during slow and steady revving, the 12 degree mark would remain at the split for a bit before it started to move. I didn’t play with this enough to see at what RPM advance started to change. I also didn’t test to see at what RPM max advance (25 deg) was achieved - I just know that at 3k it seemed to be all in.
Then the engine bay was getting a bit hot for my liking and my 5 minute garage time window was up and I had to shut down and pack up. I did not look at my distributor, I didn’t loosen it or adjusted it. I didn’t even take the cap off, and I can’t say I even know exactly what distributor I have. I believe it might be a magna spark. I don’t see a vacuum gizmo on it, so it is mechanical only.
So I am wondering how stead ‘steady’ is when using a strobe. I am also wondering how I determine what ideal total advance should be for my car, and at what RPM it should occur. I also wonder if 12 deg at 1200 rpm idle is acceptable. If it matters I have a 2332cc, the standard Pat Downs build Greg now uses with Solex/Kadron carbs.
I realize I’m only looking at a small sliver of all that should be tested so my questions are somewhat out of context, but any coaching on this part of the fun is welcome.
Jon - the noob
