The Ford Barn

Habusailor · 05-13-2019, 09:19 PM

How do you set the point dwell on a 1949 stock engine?

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WABOOM · 05-13-2019, 09:41 PM

Set the points gap at .014-.016" with a feeler gauge by loosening the screws on the points assembly and gently pivoting the breaker points open and closed. You also need to have the distributor lobe at the highest spot on the lobe. Turn the crank pulley with socket wrench (7/8?) Until the points tang is right at the peak of the lobe.
Adjusting the dwell angle and gap independently is not a possibility as I know.

BUBBAS IGNITION · 05-13-2019, 09:51 PM

Using a dwell meter hooked up to point contacts , adjust while cranking engine to spec . I believe its 28 degrees.
Understand dwell is a "average" of all eight cam lobes etc and represents the time between lobes the contacts are closed allowing the coil magnetic field to build up for proper firing......

WABOOM · 05-13-2019, 09:58 PM

If the gap is correct, what does it mean if the dwell is not in spec.? The lobes are worn?

flathead4rd · 05-14-2019, 08:34 AM

If I remember this right. Dwell does not affect timing but timing does affect dwell. I'm sure someone here will correct me if I'm wrong.

JSeery · 05-14-2019, 08:37 AM

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Quote:

Originally Posted by flathead4rd

If I remember this right. Dwell does not affect timing but timing does affect dwell. I'm sure someone here will correct me if I'm wrong.

Other way around isn't it?

V8 Bob · 05-14-2019, 08:41 AM

Quote:

Originally Posted by WABOOM

If the gap is correct, what does it mean if the dwell is not in spec.? The lobes are worn?

If the contact surfaces are not flat (new) or are out of alignment, true gap cannot be measured accurately and the actual dwell will be incorrect.

V8 Bob · 05-14-2019, 09:40 AM

Quote:

Originally Posted by flathead4rd

If I remember this right. Dwell does not affect timing but timing does affect dwell. I'm sure someone here will correct me if I'm wrong.

Dwell directly affects timing, and is the reason you always want to set dwell before checking or adjusting timing.

BUBBAS IGNITION · 05-14-2019, 10:29 AM

For every degree of dwell, timing is changed two degrees.........

tubman · 05-14-2019, 11:01 AM

Ideally, wouldn't you want to set the gap first and the check the dwell/ After that, you could adjust the gap (close it a little to increase dwell and vice versa) to get the dwell to spec. THEN, set the timing. I know it sounds a little finicky, but I'm retired and have a lot of time. Plus, I like to do things like this.

34fordy · 05-14-2019, 11:45 AM

Quote:

Originally Posted by tubman

Ideally, wouldn't you want to set the gap first and the check the dwell/ After that, you could adjust the gap (close it a little to increase dwell and vice versa) to get the dwell to spec. THEN, set the timing. I know it sounds a little finicky, but I'm retired and have a lot of time. Plus, I like to do things like this.

If memory serves me, and sometimes not----When GM came out with the points that were adjusted from the outside of the distributor, all we did was install the points, hook up a dwell meter, and set to 28-32 degree dwell. Usually right down the middle at 30 degrees. Did not even think about the .016 point gap.

WABOOM · 05-14-2019, 11:59 AM

I'm not the OP, but my distributor won't rotate. Is there 2 bolt clamping it down?

51 MERC-CT · 05-14-2019, 01:34 PM

Quote:

Originally Posted by WABOOM

I'm not the OP, but my distributor won't rotate. Is there 2 bolt clamping it down?

Should be just one bolt and pinch clamp at about the 9-10 o'clock position.
Might need a little persuasion.

WABOOM · 05-14-2019, 01:42 PM

Ok. I'll persuade it.

rotorwrench · 05-14-2019, 01:50 PM

The vacuum line would be the only other factor on a load-o-matic for making the timing adjustment difficult to rotate. If the distributor body is gummed up where it fits into the timing cover then that might also make it difficult. 8BA family engines all just have the same single clamp to hold them down to the head.

If a person sets the point gap on one lobe of the distributor cam, it may not be the same at 90 degrees from the point due to cam lobe wear or distributor bushing or shaft wear. If points don't open enough then the dwell time will be less than spec. If they open too much then dwell time will be more than spec. It's just an average of point opening amounts for all the different lobes. GM distributors with the window and adjustable points could be adjusted while running but most of the older ones, it's just adjust and check by trial and error until it's as close as it will get.

Generally, all it takes is to properly set the point gap to specs. If all is in good condition and order, it should have the correct dwell time.

05-13-2019, 09:19 PM	#1
Habusailor Senior Member Join Date: Dec 2016 Location: Fargo North Dakota Posts: 264	Dwell How do you set the point dwell on a 1949 stock engine? Sent from my iPhone using Tapatalk

05-13-2019, 09:41 PM	#2
WABOOM Senior Member Join Date: Jun 2018 Location: Minnesota Posts: 347	Re: Dwell Set the points gap at .014-.016" with a feeler gauge by loosening the screws on the points assembly and gently pivoting the breaker points open and closed. You also need to have the distributor lobe at the highest spot on the lobe. Turn the crank pulley with socket wrench (7/8?) Until the points tang is right at the peak of the lobe. Adjusting the dwell angle and gap independently is not a possibility as I know. Last edited by WABOOM; 05-13-2019 at 09:51 PM.

05-13-2019, 09:51 PM	#3
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: Dwell Using a dwell meter hooked up to point contacts , adjust while cranking engine to spec . I believe its 28 degrees. Understand dwell is a "average" of all eight cam lobes etc and represents the time between lobes the contacts are closed allowing the coil magnetic field to build up for proper firing...... __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

05-13-2019, 09:58 PM	#4
WABOOM Senior Member Join Date: Jun 2018 Location: Minnesota Posts: 347	Re: Dwell If the gap is correct, what does it mean if the dwell is not in spec.? The lobes are worn?

05-14-2019, 08:34 AM	#5
flathead4rd Senior Member Join Date: May 2010 Location: Michigan Posts: 505	Re: Dwell If I remember this right. Dwell does not affect timing but timing does affect dwell. I'm sure someone here will correct me if I'm wrong.

05-14-2019, 10:29 AM	#9
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: Dwell For every degree of dwell, timing is changed two degrees......... __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

05-14-2019, 11:01 AM	#10
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,303	Re: Dwell Ideally, wouldn't you want to set the gap first and the check the dwell/ After that, you could adjust the gap (close it a little to increase dwell and vice versa) to get the dwell to spec. THEN, set the timing. I know it sounds a little finicky, but I'm retired and have a lot of time. Plus, I like to do things like this.

05-14-2019, 11:59 AM	#12
WABOOM Senior Member Join Date: Jun 2018 Location: Minnesota Posts: 347	Re: Dwell I'm not the OP, but my distributor won't rotate. Is there 2 bolt clamping it down?

05-14-2019, 01:42 PM	#14
WABOOM Senior Member Join Date: Jun 2018 Location: Minnesota Posts: 347	Re: Dwell Ok. I'll persuade it.

05-14-2019, 01:50 PM	#15
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,425	Re: Dwell The vacuum line would be the only other factor on a load-o-matic for making the timing adjustment difficult to rotate. If the distributor body is gummed up where it fits into the timing cover then that might also make it difficult. 8BA family engines all just have the same single clamp to hold them down to the head. If a person sets the point gap on one lobe of the distributor cam, it may not be the same at 90 degrees from the point due to cam lobe wear or distributor bushing or shaft wear. If points don't open enough then the dwell time will be less than spec. If they open too much then dwell time will be more than spec. It's just an average of point opening amounts for all the different lobes. GM distributors with the window and adjustable points could be adjusted while running but most of the older ones, it's just adjust and check by trial and error until it's as close as it will get. Generally, all it takes is to properly set the point gap to specs. If all is in good condition and order, it should have the correct dwell time.