How much can dwell angle be off?

53a1 · Post by **53a1** » Tue Jan 25, 2011 4:05 pm

Hello Everyone.

I set my dwell angle some time ago using an old meter and it runs great. I recently bought a digital meter and re-checked it and it's reading 43 deg instead of 45 deg. This is a civvy distributor and it's a Prestolite (pre Autolite) and my book calls for 45 deg.

Is 43 close enough?

Thanks.
Dave

Post by **wesk** » Tue Jan 25, 2011 11:02 pm

2 or 3 degrees either way on a 60 or 72 HP engine that peaks power at 3500 RPM will not matter.

By the way Prestolite is post Auto-Lite.

53a1 · Post by **53a1** » Wed Jan 26, 2011 5:18 pm

Thanks Wes.

I did some reading and what I've found is for every two degrees of dwell your timing will be affected by 1 degree. You need to set your dwell before anything else. Also you shouldn't have to adjust timing during tune up. Just check your dwell because the point cam surface will wear and affect your timing.

Post by **wesk** » Thu Jan 27, 2011 12:17 am

You need to set your dwell before anything else.

Actually set the point gap and inspect the distributor and check timing before you check dwell. Both point gap and timing setting affect dwell.

point cam surface will wear and affect your timing.

Actually the point's rubbing block does the wearing. The cam is metal.

dod03-52 · Post by **dod03-52** » Thu Jan 27, 2011 7:16 am

Your dwell angle should remain constant as you increase the rpm. If it moves more than a few degrees your distributer shaft bushings are worn out. If the wear is bad enough you could get weak or no spark to single cylinder and the others would be fine. I had a old Chev that would idle fine but a miss on #6 with rpm. Dwell would decrease with rpm due worn bushings---replaced dist--ran great.

Cacti_Ken · Post by **Cacti_Ken** » Thu Jan 27, 2011 2:00 pm

Is it possible to check the dwell on a 24 volt water proof distributor?

53a1 · Post by **53a1** » Thu Jan 27, 2011 10:38 pm

Thanks everyone!

Post by **wesk** » Fri Jan 28, 2011 3:27 am

Yes you can use a GI dwell meter on the M series distributors.

Cacti_Ken · Post by **Cacti_Ken** » Fri Jan 28, 2011 1:11 pm

Ok thanks, I'll be studying on how to do that when I get my meter in.

Post by **wesk** » Fri Jan 28, 2011 4:46 pm

That small threaded hex plug in the top of your distributor cap is where you connect the dwell meter.

That little short pointy do dad in the lower center of the box is the crew in dwell attachment adapter for your cap.

It's in the upper right block.

Page 3 of the instructions

The GI Dwell/Tach

Cacti_Ken · Post by **Cacti_Ken** » Fri Jan 28, 2011 7:01 pm

I don't have one of those sets yet. maybe I can rig up something with an insulator thru the hole in top of distributor.

Post by **wesk** » Fri Jan 28, 2011 9:51 pm

Take the threaded plug out and go to the hardware store and pick out one of those rubber stoppers that is the same diameter. Then use a long slender nail or pin thru the center of the stopper after you squeeze it into the opening of the cap. Press the nail down against the positive terminal of the coil while lifting the stopper slightly and the stopper will maintain pressure on the nail for you.

If you place a normal $30 or $40 dollar per hour value on your time it won't take long to make the set very economically feasable at $50 to $75 a set.

I have three of those sets and a tank set. They make troubleshooting the M series a quick and dirty snap.

Cacti_Ken · Post by **Cacti_Ken** » Fri Jan 28, 2011 11:36 pm

My thoughts were on those lines. I had cork stopper on the brain. But wasn't sure of the insulating quality. I would have used an ohm meter to determine that first. But the rubber stopper is definately better.

How much can dwell angle be off?

How much can dwell angle be off?

Dwell angle to check dist wear