how to set dwell

[tie_one_on]

On a Prestolite, bolt on cap distibutor, how do you set dwell? If the manaul call for 29-33 degrees dwell and the points gap is 18 thousandths, and you set the points at that but the dwell is 25 degrees, what adjustments are made to correct this offset. The distributor plate has a triangler cut out for adjustments and the points a have an notch for adjustment how (besides trial and error do you adjust dwell)? I'm used to the pre 70's GM points distributors with the little windows for dwell adjustments. Before you flame me for mentioning automotive distributors on this site, I know the difference.

 

[jeff13601]

Re: how to set dwell

Don has put in many good post on the two. It is more imp to have the dwell correct then the gap. I asked this same question as I was also confused. Basically what I was told is that if the dist and everything were perfect when you set the gap the dwell would also be right. Set the gap to get it running and then get a dwell meter and set the dwell

 

[Don S]

Re: how to set dwell

29-33 sounds like the dwell for a Ford 460, not a 70's GM product.<br />Dwell is the number of degrees that the points are closed on the distributor lobes.<br />Less dwell means you have the points too close together, too high a dwell means the points gap is too wide.<br />The reason for using a dwell meter is because not everybody can feel the difference of the .001 or .002 difference that makes the difference between a good running engine and a "Yea, it runs" engine. I still can't get it right with a feeler gauge and I have tried for, uh... lets see,..... several (over 20) years now.

 

[tie_one_on]

Re: how to set dwell

Don thanks for the come back. But how to you set the dwell (BTW it's a Ford 302)? I was referring to the old style GM cars becuse they had the little door you could adjust the dwell with the engine running. Obviously on the prestolite distributor there is no door. Is there a way you can set the dwell with your meter by having the key on, cap off? Or do you have to try to set the points, put cap back on, start engine and check dwell, if off start over? Thanks

 

[xltier]

Re: how to set dwell

hook your dwell meter up and have someone crank the engine over while you adjust the dwell with the cap off.pull the rotor out of the way also.

 

[Don S]

Re: how to set dwell

Stick a screwdrive in the triangular hole and the notch in the points and move the points till you get the proper dwell. You will have to loosen the screw a little before you can move the points.<br />With some dwell meters you can hook up the dwell meter and crank the engine and set the dwell as xltier mentioned. Some it doesn't work, and yes, if it's not right you take the cap off and do it again.

 

[jeff13601]

Re: how to set dwell

I think he is confused on how to use the dwell meter.The engine does not need to be running. Pull the cap, rotor and disconnect coil wire and ground it. I borrowed a friends book and meter but I will try and remember. With this meter the black wire went to the neg battery term and the green went to the neg side of the coil. Then have someone crank the motor while you do what don says and adjust the points until you reach the desired dwell. If I have made a mistake someone will straighten me out

 

[Reel Poor]

Re: how to set dwell

Always hook dwell or tach meter lead to the negitive side of the coil.

 

[jeff13601]

Re: how to set dwell

WOOPS, Its Sunday morning guys. Thank gosh for editing, lol

 

[rjohson]

Re: how to set dwell

high dwell means the gap is small and the points stay closed longer, wide gap means the dwell is low and the points open up quickerwhen you cranking the engine set the dwellset your dwell at 40 once you put cap and every thing on it will drop down within your spec at least 35 i know your specs are 29 33 but the extra time the points stay closed will give you a better spark.

 

[jeff13601]

Re: how to set dwell

I have never heard of the cap being on dropping the dwell five degrees. Could you explain this to me so I understand

 

[Don S]

Re: how to set dwell

Putting the cap on has nothing to do with the dwell, but when setting dwell while cranking, the dwell will just normally comes out less once you start it compared to cranking. <br />My dwell meter must be set 2° higher than what I want when running. One of the other guys in the shop with a different one only sets his 1° higher than needed. Obviously _al_ needs to set his 5° higher. I would also set the dwell within specs, and not higher so the points stay closed longer.

 

[tie_one_on]

Re: how to set dwell

Thanks Don S and XLTIER, That's what I wanted to know that with the engine turning over and the cap & rotor off you could set the dwell. Jeff13601 - I'm not confused how to use a dwell meter, just wanted to know if there was a better way the setting the points, starting the engine and checking dwell.

 

[jeff13601]

Re: how to set dwell

Confused was probably the wrong term to use about the meter. I thought you were unsure if it could be done with motor not running. Hope I didnt offend you