dwell problems

[lynnboy021]

I have new points and I set the gap to 18 but I am trying to set the dwell but my meter is bouncing back n forth really fast.... I was reading the adult sticky on setting dwell and it says if my meter is bouncing I have a loose ground or something like that... anyways I looked at all the grounds and can't find any problems? ???? Do I really need to set dwell if motor starts n runs fine????

 

[LAC_STS]

Re: dwell problems

I would figure it out so you can set the dwell to the correct spec. It's probably something stupid.

 

[bruceb58]

Re: dwell problems

How do you have your dwell meter hooked up?

Which meter do you have?

 

[lynnboy021]

Re: dwell problems

How do you have your dwell meter hooked up?

Which meter do you have?

I have it hooked up the way Don S has it on his sticky... I have a jumper wire from center post of coil to ground on the intake and then the red wire from meter to neg side of coil and black wire to ground on a bolt from the exhaust... sorry forgot whats the name of the meter oh and I set the meter to 8 cyl and dwell

 

[bruceb58]

Re: dwell problems

Normally, you have the red of the meter to the neg of the coil and black lead to ground and that's it. Have no idea what you are doing with the center post.

How can you have the engine run and measure dwell if you are doing that ground to the center post?

EDIT: Now I think I know what you were doing. You were just cranking the engine with the cap off to set the points. That is fine. Once you set the dwell close that way, put the cap back on and start the engine and confirm that the dwell is the correct amount. if it isn't, take the cap back off and readjust the points. Sometimes it take a couple tries to get it right where you want it.

Once you get the engine running and th dwell is correct, rev the engine and observe the dwell. If it varies much at all, this means your distributor bushing is worn.

After you are all done with the dwell, check your timing as changing the dwell changes the timing.

 

[lynnboy021]

Re: dwell problems

[QUOTE
Once you get the engine running and th dwell is correct, rev the engine and observe the dwell. If it varies much at all, this means your distributor bushing is worn./QUOTE]

I might be wrong but what u saying is that if dwell needs to be at let's say if my dwell needs to be at 28 and I start the motor and rev it and the dwell moves then my bushing is gone????

 

[bruceb58]

Re: dwell problems

I might be wrong but what u saying is that if dwell needs to be at let's say if my dwell needs to be at 28 and I start the motor and rev it and the dwell moves then my bushing is gone????

Yes. It might move a little, but it shouldn't move much

 

[Bt Doctur]

Re: dwell problems

Remember, dwell is the amount of time the points are closed. Its measured in degrees. The point gap affects dwell.
As long as points are between .018 and .022 and the motor runs fine your ok. But if you were really concerned about having the dwell number correct then adjust the point gap to obtain that reading and record it. Next time you install points, just set them to that gap and the dwell will be the same.

 

[gm280]

Re: dwell problems

Remember, dwell is the amount of time the points are closed. Its measured in degrees. The point gap affects dwell.
As long as points are between .018 and .022 and the motor runs fine your ok. But if you were really concerned about having the dwell number correct then adjust the point gap to obtain that reading and record it. Next time you install points, just set them to that gap and the dwell will be the same.

I have to agree with your assessment about dwell being the amount of time the points are closed and that reading being the time in degrees as well... However, dwell isn't going to stay at the reading when they were initially installed and set. WHY? because as the rubbing block contact area and spring tension and actual point contact areas wear, the dwell will not stay the same. It will be close. but certainly not at the initial setting. So with that known, I'd skip trying to get the precise dwell reading and just set your points to 0.020" and go fishing... There are reasons for dwell to stay close the proper amount of degrees, and that time is to let the primary side of the spark coils to build up a charge and saturate (if closed long enough). That build up of primary side voltage and current makes for a higher secondary spark with greater current as well. But like everything in this world there is a trade off and so the manufacturers provided the time in degrees for that trade of time... Just set the points to 0.020" and happy boating!

 

[bruceb58]

Re: dwell problems

You always double check with a dwell meter. Go back and look at DonS's posts and he said the exact same thing.

 

[Levinz11]

Re: dwell problems

My dwell moves a bit too when revving motor lynn. 26 year old distributor to blame I guess.

 

[lynnboy021]

Re: dwell problems

Thanks for all the info guys..... I will let you guys know how it went thanks again

 

[gm280]

Re: dwell problems

bruceb58, If I'm not mistaken, Ford, some long years ago, use to install a little metal slide window in their distributor caps so you could take a Allen tool to actual set the dwell while the engine was running. That was the easiest dwell setting I ever remembered. Others had to be shut down and a flat bladed screwdriver was used to adjust the points in a trial and error method until you got them set correctly...

 

[Maclin]

Re: dwell problems

Hey gm, just a point of order, that was GM distributors in 60's and 70's. Fords and MoPars had the trial and error approach

 

[MikDee]

Re: dwell problems

bruceb58, If I'm not mistaken, Ford, some long years ago, use to install a little metal slide window in their distributor caps so you could take a Allen tool to actual set the dwell while the engine was running. That was the easiest dwell setting I ever remembered. Others had to be shut down and a flat bladed screwdriver was used to adjust the points in a trial and error method until you got them set correctly...

As far as I know, that was all GM vehicles! I still couldn't get it right without a meter!

 

[gm280]

Re: dwell problems

Hey gm, just a point of order, that was GM distributors in 60's and 70's. Fords and MoPars had the trial and error approach

That should show you all how old my brain is getting these days....I think! :stupid:

 

[bruceb58]

Re: dwell problems

What i do is measure the dwell while the engine is running to see how far I am off. Then I remove the cap and just crank and measure. There seems to be an offset when you do it that way. Adjust the dwell while cranking until you get the correct dwell taking into consideration of the offset. Then check while running. Can get it almost perfect that way.

 

[Lou C]

Re: dwell problems

Yep I had a '72 Chevy Impala with the Delco window distributor, it was so easy to set the points it made up for having the dist way back up against the firewall. I still have the flexible allen adjusting tool for those!
A couple of other points, yes you can set the point gap to the higher end of the spec and it will stay in spec longer, but since point gap and dwell are inversely related (dwell is the # of degrees the dist shaft turns with the points closed) that might lower the spark output some.
You should put some dist cam grease on the dist cam to lube the rubbing block. Just a little you don't want it flying all over the inside of the dist....
On the Prestolite distributors with mechanical advance, you should pull off the rotor and put a few drops of motor oil on the foam in the center of the dist shaft since that lubes the advance weights and pivots so they don't get rusted in place.....

I usually replace my points every 4 seasons or so, I will crank the engine and look carefully to see if they are getting pitted or the alignment of the points is off. If they look good and the engine runs well I leave em in and check dwell, timing and idle speed. Also look at the contacts in the dist cap and replace the cap and rotor if the contacts are getting burned or corroded.