It has been a while since I had to set dwell on an actual set of points and not in a software tune. I probably threw out my old analog dwell meter 20 years ago figuring what kind of an idiot would run a car with points when we have these awesome computers. LOL, well here I am with a 70 vert. I finally got around to doing a real tune up, and figured I would start looking at where I was from a baseline. Ordered a meter to measure dwell from Amazingzon and was careful to verify it could in fact check dwell. the instructions clearly detailed how to use the meter, select cylinder count, and read your dwell down to the 10th, awesome.. Well, did not exactly work out as expected, go figure. Set the dwell with the meter set as needed carefully fine tuning the old set screw on the points after being sure I was at the exact right RPM, good engine temp, bla bla. the dwell was only maybe 6 or 8 degrees off. Next up was timing, pulled out my handy dandy induction timing light and began to go to town on a base timing dance. Again, all is well, set my 4 degrees (350/3300HP) then double checked dwell, all is good in the world. then as I flipped through the menu on the timing light, I saw it is capable of measuring dwell as well, sweet, built in QA! Well, it was far from that. the timing light was telling me my dwell was 8 or 10 degrees higher...WTF? Who to trust was my issue. Car seemed to run okay, so I decided to order a new set of GM points, condenser, and rotor simply because I am weird like that, and re run the process once the point come in. This time, I will reach back into my dark past and pull out the same matchbook I used to gap my points at the senior prom, worked then, should work now... Flash back to reality, when I installed the new points, I set the gap to .019 knowing this should be close. got her all closed up, turned the key and started checking my work. The timing light dwell measured exactly 30 degrees, the funky green meter I ordered from AMZ was saying 40 or 42. Moral of the story is you can trust the Innova 5568a timing light, but stay away from the Performance Tool W2972. hope this helps others from dealing with issues from an incorrect dwell setting. The car feels great now, so wanted to share the experience.

Crap

Good

 

I have the same timing light with dwell and also have an old late 70's early 80's analogue points test / rpm / dwell meter.

sometimes i connect both to verify the results to be sure of the accuracy.
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My Snap On MT926 has never let me down, just keeps on working.

 

Feeler guages are the way to go with fresh points or a set that has been trued up flat.

I have an old Dixco dwell meter that might still work but none of my cars have points anymore.

 

how about ordering another dwell meter (analog or digital) from amazon and take the 2/3 for accuracy.. the best part is all returnable if amazon..
that 10 degrees would bother me LOL

 

I bought a couple of real nice ones at a swap meet a few months ago. Both were in complete "tune up" kits. One was an old Dixco and the other was a Rotunda. Paid $5 for the pair and they both work great.

Look around for a good old Snap On one or similar.

JIM