The Ford Barn

Bruce Lancaster · 09-26-2014, 10:13 AM

On the brake disc...as RPM goes up (actually starting right off idle) the advance starts to move and loads the brake disc in one direction...in retarded position the slots are not being pushed forward, so piston drag holding disc back stabilizes it. While driving car is almost entirely above RPM where advance starts, and action at that disc will always be some combination of centrifugal push and restraint on same push by brake, with the brake action probably being very slight most of the time with screw way out.
It was much more important in prewar low octane days, and also with lazy pre-automatic trans drivers lugging the car to avoid the effort of shifting.

39topless · 09-26-2014, 10:42 AM

Quote:

Originally Posted by scooder

Flatjack, I see your point re the brake piston, I makes sence, I think that the piston doesn't completely lift of the plate except on the over run. I've seen with the piston removed, the timing flicking about when using a timing light. With the piston in, at idle the timing stabilised.
Wether they all do this, I don't know, but the one I seen did just this.
Mr topless, you got some things to look at an try, do report back your findings.
Martin.

Martin, Will do, Thanks

39topless · 09-26-2014, 03:14 PM

An update. I removed the distributor brake adjusting cylinder and the inner components were there. The piston did have a grove worn into it but still looked serviceable. The spring seemed to still be ok. I had to build a vacuum line using the fitting on the dissy that had been plugged and a copper line that I jimmied up to the vacuum outlet of the carb plate.
I turned the adjusting screw way out and fired her up.

YES!!!! It ran much much better. Just to experiment, I turned the screw in a couple turns and it ran like crap. Still has some stuttering at higher RPM's but at least now I can drive the damn thing again.
Thank you all for your help. My ignorance is feasting on all of your knowledge.
Phil

Bruce Lancaster · 09-26-2014, 03:49 PM

On the piston...just turn it 90 degrees and you have about 95% new surface. Check on initial timing, this can be checked with rulers, look up ruler method here. If adjustment is around center of slot it is probably ok.
Advance should start just a little above idle and come on rapidly. Brake slows down that process as a way of coping with ping from bad gas and/or bad driving.

scooder · 09-26-2014, 06:23 PM

Sounding good so far.
Keep up the fun,
Martin.

09-26-2014, 10:13 AM	#21
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: vacuum advance disabled On the brake disc...as RPM goes up (actually starting right off idle) the advance starts to move and loads the brake disc in one direction...in retarded position the slots are not being pushed forward, so piston drag holding disc back stabilizes it. While driving car is almost entirely above RPM where advance starts, and action at that disc will always be some combination of centrifugal push and restraint on same push by brake, with the brake action probably being very slight most of the time with screw way out. It was much more important in prewar low octane days, and also with lazy pre-automatic trans drivers lugging the car to avoid the effort of shifting.

09-26-2014, 03:14 PM	#23
39topless Senior Member Join Date: Sep 2013 Posts: 1,027	Re: vacuum advance disabled An update. I removed the distributor brake adjusting cylinder and the inner components were there. The piston did have a grove worn into it but still looked serviceable. The spring seemed to still be ok. I had to build a vacuum line using the fitting on the dissy that had been plugged and a copper line that I jimmied up to the vacuum outlet of the carb plate. I turned the adjusting screw way out and fired her up. YES!!!! It ran much much better. Just to experiment, I turned the screw in a couple turns and it ran like crap. Still has some stuttering at higher RPM's but at least now I can drive the damn thing again. Thank you all for your help. My ignorance is feasting on all of your knowledge. Phil Last edited by 39topless; 09-26-2014 at 11:31 PM.

09-26-2014, 03:49 PM	#24
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: vacuum advance disabled On the piston...just turn it 90 degrees and you have about 95% new surface. Check on initial timing, this can be checked with rulers, look up ruler method here. If adjustment is around center of slot it is probably ok. Advance should start just a little above idle and come on rapidly. Brake slows down that process as a way of coping with ping from bad gas and/or bad driving.

09-26-2014, 06:23 PM	#25
scooder Senior Member Join Date: Jul 2010 Posts: 2,597	Re: vacuum advance disabled Sounding good so far. Keep up the fun, Martin.