The Ford Barn

retep · 08-18-2015, 12:04 PM

What affect on timing does having gap to large or small have on advance setting?
I am trying to set 40B (1936) distributor without much success. By this I mean I have back firing through the exhaust when going downhill.

The point setting is .013
Will setting wider impact this?

When I set up advance on distributor it was at middle mark. Rough running and vacuum reading 15. Moved to full advance reading now at 17.

Will changing gap make any change for the better?

flatjack9 · 08-18-2015, 12:22 PM

A wider gap will advance the timing.

BUBBAS IGNITION · 08-18-2015, 12:48 PM

Each degree of dwell setting ( on the drivers side set ) will change timing two degrees.
Ex: A distributor that should run a 27 degree dwell setting using 22 degrees would change timing 10 engine degrees....advanced ....
Only the drivers side effects the timing the pass side effects coil build up.

As the distributor is case timed to the engine cover its important to be correct for sure....

Bob C · 08-18-2015, 02:00 PM

An exhaust leak can sometimes cause back firing when going against compression.

Bob

MGG · 08-18-2015, 02:18 PM

Should the gap on both points be set the same or are they different?

BUBBAS IGNITION · 08-18-2015, 03:17 PM

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Quote:

Originally Posted by MGG

Should the gap on both points be set the same or are they different?

Most manuals show them as being the same . On a machine the dwell setting is different per side .....The drivers side is set at 22 1/2 degrees for small points ( with pass side blocked off) and 27 degrees for strap points. Then the pass side is set running both sets at 35-36 degrees..........

Willit Stop · 08-18-2015, 04:02 PM

I posted this a few years back and it seemed to work pretty well.
https://www.fordbarn.com/forum/showth...ighlight=dwell

trainguy · 08-18-2015, 04:04 PM

Quote:

Originally Posted by flatjack9

A wider gap will advance the timing.

Are you certain of that? I think the opposite.Phil

Bob C · 08-18-2015, 05:04 PM

Quote:

Originally Posted by trainguy

Are you certain of that? I think the opposite.Phil

The sooner they open the wider the gap will be.

Bob

flatjack9 · 08-18-2015, 11:34 PM

As you increase the gap, the dwell angle will decrease because the points will open earlier. The spark occurs when the points open, hence increased spark timing.

trainguy · 08-19-2015, 04:03 AM

Your right ,fuzzy thinking on my end!My mistake,Phil

retep · 08-19-2015, 08:51 AM

I am pretty lazy guys so I am going to take off distributor (3 time) and reset points to .015 and see what happens.

As a matter of interest the last time I set advance using Henry Fords method as described in his patent application for his distributor from 1933.

retep · 08-28-2015, 02:00 PM

I'm back.
Here is my update.
I tried the lazy way (setting points at .015) and no improvement.
I used Willit Stop procedure and no change.

Before I go the route of buying a rebuild and possible electronic upgrade I would appreciate any other suggestion for my problem ie. Carburetor, vacuum leaks etc.

Symptoms once again:
Backfire in exhaust, running rough, low vacuum readings 17-18 and I believe overheating.
I did pull out choke and it did not improve road test.

Thank you for what ever you have to offer.

Mike51Merc · 08-28-2015, 02:59 PM

Back snapping/rapping/cackle on deceleration indicates a lean condition at idle. Check for vacuum leaks and possibly enrich the idle mixtures.

retep · 09-04-2015, 07:58 AM

Still playing around with solving this problem.
I once again tightened down manifold and carb (vac leak)
Cleaned and gaped plugs. Would appear to be running rich (black carbon)
Checked to make sure coil polarity correct using voltmeter
Replaced fuel pump

Could condenser be an issue? I have Dennis Carpenter coil adapter with condenser supplied.

Carb is my next consideration.
Again thanks for any input.

trainguy · 09-04-2015, 10:11 AM

A compression test may be in your future.Phil

rotorwrench · 09-04-2015, 12:14 PM

Condensers are definitely on the list of possibilities. If they don't charge up completely or leak the charge out as fast as it is drawn then the breaker points and the ignition function will suffer greatly.

Black coated plugs indicate either poor ignition function, excessive oil in the combustion area, or a rich fuel mix from something like an internal carb leak. Those old carbs can leak from bad gaskets or power valves depending on the make of carburetor. A compression check will tell you if the rings or valves are suspect.

retep · 09-04-2015, 01:24 PM

[B]
[/B ]I will replace condenser. Do you have NAPA number for 1936 (40B) condenser?
I will have to borrow a compression gauge so it might be a few days before I report back.

Mark's 37 · 09-04-2015, 05:01 PM

Just a thought. Have you cleaned or replaced the fouled plugs? If you have made adjustments/changes and the plugs are still fouled it will continue to run badly.

retep · 09-04-2015, 05:45 PM

I pulled plugs. They were as described then cleaned and gapped.
I haven't run car other then test. No improvement.

08-18-2015, 12:04 PM	#1
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Point gap affect on timing What affect on timing does having gap to large or small have on advance setting? I am trying to set 40B (1936) distributor without much success. By this I mean I have back firing through the exhaust when going downhill. The point setting is .013 Will setting wider impact this? When I set up advance on distributor it was at middle mark. Rough running and vacuum reading 15. Moved to full advance reading now at 17. Will changing gap make any change for the better?

08-18-2015, 12:22 PM	#2
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Point gap affect on timing A wider gap will advance the timing.

08-18-2015, 12:48 PM	#3
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: Point gap affect on timing Each degree of dwell setting ( on the drivers side set ) will change timing two degrees. Ex: A distributor that should run a 27 degree dwell setting using 22 degrees would change timing 10 engine degrees....advanced .... Only the drivers side effects the timing the pass side effects coil build up. As the distributor is case timed to the engine cover its important to be correct for sure.... __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

08-18-2015, 02:00 PM	#4
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 8,751	Re: Point gap affect on timing An exhaust leak can sometimes cause back firing when going against compression. Bob

08-18-2015, 02:18 PM	#5
MGG Senior Member Join Date: Apr 2015 Location: Oregon City, OR Posts: 285	Re: Point gap affect on timing Should the gap on both points be set the same or are they different?

08-18-2015, 04:02 PM	#7
Willit Stop Senior Member Join Date: Feb 2013 Location: Eureka Calif. Posts: 969	Re: Point gap affect on timing I posted this a few years back and it seemed to work pretty well. https://www.fordbarn.com/forum/showth...ighlight=dwell

08-18-2015, 11:34 PM	#10
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Point gap affect on timing As you increase the gap, the dwell angle will decrease because the points will open earlier. The spark occurs when the points open, hence increased spark timing.

08-19-2015, 04:03 AM	#11
trainguy Senior Member Join Date: May 2010 Location: Lehighton Pa Posts: 1,085	Re: Point gap affect on timing Your right ,fuzzy thinking on my end!My mistake,Phil

08-19-2015, 08:51 AM	#12
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Re: Point gap affect on timing I am pretty lazy guys so I am going to take off distributor (3 time) and reset points to .015 and see what happens. As a matter of interest the last time I set advance using Henry Fords method as described in his patent application for his distributor from 1933.

08-28-2015, 02:00 PM	#13
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Re: Point gap affect on timing I'm back. Here is my update. I tried the lazy way (setting points at .015) and no improvement. I used Willit Stop procedure and no change. Before I go the route of buying a rebuild and possible electronic upgrade I would appreciate any other suggestion for my problem ie. Carburetor, vacuum leaks etc. Symptoms once again: Backfire in exhaust, running rough, low vacuum readings 17-18 and I believe overheating. I did pull out choke and it did not improve road test. Thank you for what ever you have to offer.

08-28-2015, 02:59 PM	#14
Mike51Merc Senior Member Join Date: May 2010 Location: Northeast Pennsylvania Posts: 1,582	Re: Point gap affect on timing Back snapping/rapping/cackle on deceleration indicates a lean condition at idle. Check for vacuum leaks and possibly enrich the idle mixtures.

09-04-2015, 07:58 AM	#15
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Re: Point gap affect on timing Still playing around with solving this problem. I once again tightened down manifold and carb (vac leak) Cleaned and gaped plugs. Would appear to be running rich (black carbon) Checked to make sure coil polarity correct using voltmeter Replaced fuel pump Could condenser be an issue? I have Dennis Carpenter coil adapter with condenser supplied. Carb is my next consideration. Again thanks for any input.

09-04-2015, 10:11 AM	#16
trainguy Senior Member Join Date: May 2010 Location: Lehighton Pa Posts: 1,085	Re: Point gap affect on timing A compression test may be in your future.Phil

09-04-2015, 12:14 PM	#17
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,431	Re: Point gap affect on timing Condensers are definitely on the list of possibilities. If they don't charge up completely or leak the charge out as fast as it is drawn then the breaker points and the ignition function will suffer greatly. Black coated plugs indicate either poor ignition function, excessive oil in the combustion area, or a rich fuel mix from something like an internal carb leak. Those old carbs can leak from bad gaskets or power valves depending on the make of carburetor. A compression check will tell you if the rings or valves are suspect.

09-04-2015, 01:24 PM	#18
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Re: Point gap affect on timing [B] [/B ]I will replace condenser. Do you have NAPA number for 1936 (40B) condenser? I will have to borrow a compression gauge so it might be a few days before I report back. Last edited by retep; 09-04-2015 at 06:59 PM. Reason: Correction

09-04-2015, 05:01 PM	#19
Mark's 37 Senior Member Join Date: Jul 2015 Location: Aptos, Ca Posts: 355	Re: Point gap affect on timing Just a thought. Have you cleaned or replaced the fouled plugs? If you have made adjustments/changes and the plugs are still fouled it will continue to run badly.

09-04-2015, 05:45 PM	#20
retep Member Join Date: Aug 2013 Location: Owen Sound, Ontario, CANADA Posts: 48	Re: Point gap affect on timing I pulled plugs. They were as described then cleaned and gapped. I haven't run car other then test. No improvement.