The Ford Barn

Barry in St.Paul · 06-24-2010, 08:37 PM

I have had a Bratton's "B" distributor cam on my 'A, and just purchased a new Snyder's cam to rebuild a spare distributor, so I measured the run-out on them with my dial indicator while it was convenient with the lower-body in the vise. Just for fun, I measured an old original cam I had in the junk bag (probably the one I removed to put the "B" cam on a few years ago).
I was surprised by the results. Both the Bratton's and Snyder's cams are advertised as "precision machined", etc. etc. and improved performance. Here are the measurements for each of the four lobes on the three cams: (zeroed on first lobe, then recorded both low and high point for each lobe without re-zeroing. So, some variation also on the low-point, if that matters any)
Bratton's B: 0 to 0.0255" / 0 to 0.026 / 0.001 to 0.27 / 0 to 0.026
Snyder's : 0 to 0.265" / 0.001 to 0.028 / 0.0015 to 0.027 / 0 to 0.0255
original Ford: 0 to 0.025" / 0 to 0.025 / 0 to 0.025 / 0 to 0.025

I was surprised by the almost perfect Ford cam! Maybe the "B" cams are not quite as precise because more difficult to grind? (more complex profile??). I would think something like that WOULD be 'better' today with CNC grinding machines and such.
Anyway, debating about running the old Ford cam in my freshly rebuilt distributor, restored to original system with wire and original style point. Only question is that the old Ford cam has some minor pitting and wondering if that will significantly wear the points fiber-arm faster, and whether the thousandth or two difference between lobes in the "new" cams is really going to be noticable?
I also noticed the Snyder's cam has a matte surface, and comes with an explantory note saying it was bead-blasted to better-retain the cam lube, but seems pretty rough for a cam! The Brattons and Ford cams are highly-polished.
What do you think?
And, do you notice any difference between the 'B' cam profile and the original 'A'? They advertise it as hotter spark to keep the plugs from fouling, but with my 5.9 Brumfield head, not sure that is any benefit to me.
By the way, when I disassembled my current 'modern' distributor, I saw the same thing as Tom Endy noted earlier, with my 'wireless' lower-plate. It has burn marks on it, and I have less than 500 miles on the car! Back to the wire for me.

Tom Wesenberg · 06-24-2010, 08:43 PM

More important than the lobe lift is the timing of each lobe. Do the points break open exactly every 90*?

Barry in St.Paul · 06-24-2010, 08:50 PM

Tom, how would I precisely determine that? (whether points break at EXACTLY 90deg)
Welcome back! Again, very sorry to hear about your mom!! :-(

ursus · 06-24-2010, 09:06 PM

Among some NORS and NOS Ford parts that I bought from an old restorer were several Varco brand "B" distributor cams in the original packaging. I compared them to the original Ford product and found them to be almost spot-on with Ford for the dimensions you have cited. I also checked with a degree wheel and found them to have 90 degree uniformity as well. I think the general quality of some of the NORS parts made in the later "30's and "40's was much better than some of the best repop stuff available nowadays.

I have never actually tried to compare the "A" and "B" cams for performance purposes and don't recall ever seeing a valid test.

Bob C · 06-24-2010, 10:13 PM

Vince, all I Could find in the 32 service bulletins was "The A-12210
distributor cam should never be used in the new distributor." This was
in July '32 bulletin.

Bob

van Dyck · 06-24-2010, 10:40 PM

Sponsored Links (Register now to hide all advertisements)

Installing your distributor into a distributor machine and spinning it @ approximately 500RPM, the synchrograph should "flash" at the 90* marks.

Bruce Lancaster · 06-25-2010, 09:16 AM

"how would I precisely determine that?"

Get a degree wheel/protractor and mount it up top...the mounting will take a little improv, maybe a bolt that will slip into the center screw hole of the cam.
My favorite for little projects is a dirt-cheap plastic one from Home Depot found with rulers and angle finders...True Angle brand name, it is an accessory for the basic True-angle device and is only a couple of bucks. A set of step drills allows opening the center hole to any size with very close preservation of the accurate center, so you can work it into many auto applications. Buy several...you will be intrigued by the angle checking and will be adapting the things to other projects!
I have a set of 3 step-drills which I use, turning by hand, to increase the hole size...this style of drill has a ramp from size to size which serves to maintain center as you move up one size at a time.

06-24-2010, 08:37 PM	#1
Barry in St.Paul Senior Member Join Date: May 2010 Posts: 118	Distributor Cams; original vs two new ones I have had a Bratton's "B" distributor cam on my 'A, and just purchased a new Snyder's cam to rebuild a spare distributor, so I measured the run-out on them with my dial indicator while it was convenient with the lower-body in the vise. Just for fun, I measured an old original cam I had in the junk bag (probably the one I removed to put the "B" cam on a few years ago). I was surprised by the results. Both the Bratton's and Snyder's cams are advertised as "precision machined", etc. etc. and improved performance. Here are the measurements for each of the four lobes on the three cams: (zeroed on first lobe, then recorded both low and high point for each lobe without re-zeroing. So, some variation also on the low-point, if that matters any) Bratton's B: 0 to 0.0255" / 0 to 0.026 / 0.001 to 0.27 / 0 to 0.026 Snyder's : 0 to 0.265" / 0.001 to 0.028 / 0.0015 to 0.027 / 0 to 0.0255 original Ford: 0 to 0.025" / 0 to 0.025 / 0 to 0.025 / 0 to 0.025 I was surprised by the almost perfect Ford cam! Maybe the "B" cams are not quite as precise because more difficult to grind? (more complex profile??). I would think something like that WOULD be 'better' today with CNC grinding machines and such. Anyway, debating about running the old Ford cam in my freshly rebuilt distributor, restored to original system with wire and original style point. Only question is that the old Ford cam has some minor pitting and wondering if that will significantly wear the points fiber-arm faster, and whether the thousandth or two difference between lobes in the "new" cams is really going to be noticable? I also noticed the Snyder's cam has a matte surface, and comes with an explantory note saying it was bead-blasted to better-retain the cam lube, but seems pretty rough for a cam! The Brattons and Ford cams are highly-polished. What do you think? And, do you notice any difference between the 'B' cam profile and the original 'A'? They advertise it as hotter spark to keep the plugs from fouling, but with my 5.9 Brumfield head, not sure that is any benefit to me. By the way, when I disassembled my current 'modern' distributor, I saw the same thing as Tom Endy noted earlier, with my 'wireless' lower-plate. It has burn marks on it, and I have less than 500 miles on the car! Back to the wire for me. Last edited by Barry in St.Paul; 06-24-2010 at 08:43 PM.

06-24-2010, 08:43 PM	#2
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Distributor Cams; original vs two new ones More important than the lobe lift is the timing of each lobe. Do the points break open exactly every 90*?

06-24-2010, 08:50 PM	#3
Barry in St.Paul Senior Member Join Date: May 2010 Posts: 118	Re: Distributor Cams; original vs two new ones Tom, how would I precisely determine that? (whether points break at EXACTLY 90deg) Welcome back! Again, very sorry to hear about your mom!! :-(

06-24-2010, 09:06 PM	#4
ursus Senior Member Join Date: May 2010 Location: Oregon Posts: 1,375	Re: Distributor Cams; original vs two new ones Among some NORS and NOS Ford parts that I bought from an old restorer were several Varco brand "B" distributor cams in the original packaging. I compared them to the original Ford product and found them to be almost spot-on with Ford for the dimensions you have cited. I also checked with a degree wheel and found them to have 90 degree uniformity as well. I think the general quality of some of the NORS parts made in the later "30's and "40's was much better than some of the best repop stuff available nowadays. I have never actually tried to compare the "A" and "B" cams for performance purposes and don't recall ever seeing a valid test.

06-24-2010, 10:13 PM	#5
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 8,751	Re: Distributor Cams; original vs two new ones Vince, all I Could find in the 32 service bulletins was "The A-12210 distributor cam should never be used in the new distributor." This was in July '32 bulletin. Bob

06-24-2010, 10:40 PM	#6
van Dyck Senior Member Join Date: May 2010 Location: Saskatchewan, Canada Posts: 190	Re: Distributor Cams; original vs two new ones Sponsored Links (Register now to hide all advertisements) Installing your distributor into a distributor machine and spinning it @ approximately 500RPM, the synchrograph should "flash" at the 90* marks.

06-25-2010, 09:16 AM	#7
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Distributor Cams; original vs two new ones "how would I precisely determine that?" Get a degree wheel/protractor and mount it up top...the mounting will take a little improv, maybe a bolt that will slip into the center screw hole of the cam. My favorite for little projects is a dirt-cheap plastic one from Home Depot found with rulers and angle finders...True Angle brand name, it is an accessory for the basic True-angle device and is only a couple of bucks. A set of step drills allows opening the center hole to any size with very close preservation of the accurate center, so you can work it into many auto applications. Buy several...you will be intrigued by the angle checking and will be adapting the things to other projects! I have a set of 3 step-drills which I use, turning by hand, to increase the hole size...this style of drill has a ramp from size to size which serves to maintain center as you move up one size at a time.