The Ford Barn

31Abone · 06-09-2014, 11:47 PM

Distributor acts like a uneven cam as I rotate shaft .that is one lobe is 30 thou next lobe 20 thou and so-on...tried two cams both similar checked shaft play seems real tight ? whats going on here ???

Mike V. Florida · 06-09-2014, 11:50 PM

Bushings not reamed in the center.

Received this PM

Hi Mike,
The bushing is fixed so if it were off center, it would not impact the varying gap as the center of the shaft stays at center of reamed bushing.

I have seen the cam machining on new distributor shafts be off (concentric)as much as .004" which translates into .008" when spun 360 degrees. Given some old cams were also off, it is possible the two are adding...but the amount he is observing seems over the top of possibility.

Good Day Mike!

Dave Gerold

MikeK · 06-10-2014, 12:05 AM

Center hole in upper plate may be a sloppy fit to the casting. Peen around plate hole to tighten it if there is any sideways play. The three tabs that ride in the slot are NOT what holds it centered.

juke joint johnny · 06-10-2014, 02:44 AM

When this happened to me the shaft was worn out .!! Crap repro part that had only been in there for 500 miles.

Have you removed the distributor ? to check that the shaft is tight in the distributor bushings no sideways play !!

John Cochran

quickchange · 06-10-2014, 04:26 AM

Couple of years ago we had the same problem with NEW top shaft , seems when they were machined out of round & one point reading was 5-7thou less than the other 3 ,contacted the supplier, they airfreighted another batch from a differant supplier , same thing , their 3rd supplier was able to send yet another batch of which checked out correct ,Mac,s often send me parts to check , So i beleive you have an out of round shaft where the rotor fits , We set them up with a dial guage kit i purchased at a National meet , Hope this helps , Derek from still wet NZ

Brian T · 06-10-2014, 03:17 PM

Sponsored Links (Register now to hide all advertisements)

I was reusing what I thought was a good used shaft and had the same problem, after going thru all other possible causes I tried a different shaft which fixed the problem, must have been from that bad batch.
Derek, most of the wet here on my manor is coming out of a can, we sure could use some of your rain.
Regards Brian.

quickchange · 06-10-2014, 05:40 PM

Brian Ill deliver some in Feb, ?? My devise is a clamp that fits on the dissy, with various hole in the side of which your dial gauge fits in, can measure point gap, cam run out , etc, that's how we picked up out of round shafts only where the cam fits on, this area has been machined down to take the cam ,

d.j. moordigian · 06-10-2014, 05:45 PM

Quote:

Originally Posted by forever4

Here's how I check distributor shafts. Original Ford NOS are always right on.
Distributor shaft measurement on FordBarn

Ahhhhh.........so that's what those slots are for in the V blocks.....

Big John · 06-13-2014, 10:59 AM

Also check the distributor cam with a micrometer... Most repro cams are not made accurare on the lobes. Try to stay to an original parts.....hope it helps

Terry,NJ · 06-13-2014, 12:21 PM

Hmmmmm ! Good Post! I am having some ignition issues that seem like they may be caused by this too. But I said" nahhhh, that couldn't be!" But I see now how it could be. Just bore the hole in the cam a couple of thousandths off true center and she will not ever run right! Sloppy machine work will do it every time!
Terry

d.j. moordigian · 06-13-2014, 12:44 PM

Find someone with a Distributor machine,..it solves a ton of problems.
I've used mine for the past 40+ years....

chl · 06-13-2014, 01:41 PM

this thread makes me wonder how they ever kept these cars running 85 years ago. must have been wizards with that tool kit.

Bob C · 06-13-2014, 01:46 PM

Quote:

Originally Posted by chl

this thread makes me wonder how they ever kept these cars running 85 years ago. must have been wizards with that tool kit.

85 years ago they were new and they also had genuine Ford parts
to repair them not Chinese junk.

Bob

Purdy Swoft · 06-13-2014, 01:54 PM

The model A was built for the common man . The common man could understand and do things that most of the people that now have model A's can't understand or do.

06-09-2014, 11:47 PM	#1
31Abone Senior Member Join Date: Apr 2013 Location: Big pine Ca 93513 Posts: 797	uneven point gap as dist is rotated Distributor acts like a uneven cam as I rotate shaft .that is one lobe is 30 thou next lobe 20 thou and so-on...tried two cams both similar checked shaft play seems real tight ? whats going on here ???

06-09-2014, 11:50 PM	#2
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: uneven point gap as dist is rotated Bushings not reamed in the center. Received this PM Hi Mike, The bushing is fixed so if it were off center, it would not impact the varying gap as the center of the shaft stays at center of reamed bushing. I have seen the cam machining on new distributor shafts be off (concentric)as much as .004" which translates into .008" when spun 360 degrees. Given some old cams were also off, it is possible the two are adding...but the amount he is observing seems over the top of possibility. Good Day Mike! Dave Gerold __________________ What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II Last edited by Mike V. Florida; 06-11-2014 at 04:00 AM.

06-10-2014, 12:05 AM	#3
MikeK Senior Member Join Date: May 2010 Location: Windy City Posts: 2,919	Re: uneven point gap as dist is rotated Center hole in upper plate may be a sloppy fit to the casting. Peen around plate hole to tighten it if there is any sideways play. The three tabs that ride in the slot are NOT what holds it centered.

06-10-2014, 02:44 AM	#4
juke joint johnny Senior Member Join Date: Feb 2012 Location: London England Posts: 908	Re: uneven point gap as dist is rotated When this happened to me the shaft was worn out .!! Crap repro part that had only been in there for 500 miles. Have you removed the distributor ? to check that the shaft is tight in the distributor bushings no sideways play !! John Cochran

06-10-2014, 04:26 AM	#5
quickchange Senior Member Join Date: May 2010 Location: Nelson. New Zealand Posts: 2,009	Re: uneven point gap as dist is rotated Couple of years ago we had the same problem with NEW top shaft , seems when they were machined out of round & one point reading was 5-7thou less than the other 3 ,contacted the supplier, they airfreighted another batch from a differant supplier , same thing , their 3rd supplier was able to send yet another batch of which checked out correct ,Mac,s often send me parts to check , So i beleive you have an out of round shaft where the rotor fits , We set them up with a dial guage kit i purchased at a National meet , Hope this helps , Derek from still wet NZ

06-10-2014, 03:17 PM	#6
Brian T Senior Member Join Date: May 2010 Location: San Diego,Ca Posts: 1,377	Re: uneven point gap as dist is rotated Sponsored Links (Register now to hide all advertisements) I was reusing what I thought was a good used shaft and had the same problem, after going thru all other possible causes I tried a different shaft which fixed the problem, must have been from that bad batch. Derek, most of the wet here on my manor is coming out of a can, we sure could use some of your rain. Regards Brian. __________________ Nothing can be made foolproof, ---- fools are ingenious bastards.

06-10-2014, 05:40 PM	#7
quickchange Senior Member Join Date: May 2010 Location: Nelson. New Zealand Posts: 2,009	Re: uneven point gap as dist is rotated Brian Ill deliver some in Feb, ?? My devise is a clamp that fits on the dissy, with various hole in the side of which your dial gauge fits in, can measure point gap, cam run out , etc, that's how we picked up out of round shafts only where the cam fits on, this area has been machined down to take the cam ,

06-13-2014, 10:59 AM	#9
Big John Senior Member Join Date: May 2010 Posts: 416	Re: uneven point gap as dist is rotated Also check the distributor cam with a micrometer... Most repro cams are not made accurare on the lobes. Try to stay to an original parts.....hope it helps

06-13-2014, 12:21 PM	#10
Terry,NJ Senior Member Join Date: Nov 2013 Location: Northern Bucks Co. Pa Posts: 632	Re: uneven point gap as dist is rotated Hmmmmm ! Good Post! I am having some ignition issues that seem like they may be caused by this too. But I said" nahhhh, that couldn't be!" But I see now how it could be. Just bore the hole in the cam a couple of thousandths off true center and she will not ever run right! Sloppy machine work will do it every time! Terry

06-13-2014, 12:44 PM	#11
d.j. moordigian Senior Member Join Date: May 2010 Location: Fresno, Ca. Posts: 3,636	Re: uneven point gap as dist is rotated Find someone with a Distributor machine,..it solves a ton of problems. I've used mine for the past 40+ years....

06-13-2014, 01:41 PM	#12
chl Member Join Date: Aug 2013 Location: Nicholson, Pa. Posts: 84	Re: uneven point gap as dist is rotated this thread makes me wonder how they ever kept these cars running 85 years ago. must have been wizards with that tool kit.

06-13-2014, 01:54 PM	#14
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: uneven point gap as dist is rotated The model A was built for the common man . The common man could understand and do things that most of the people that now have model A's can't understand or do.