Anyone here ever strobe your distributor? Have read about it in the manuals for these trucks, but have never had my dist. done. Rather curious, since at some point, I need to overhaul the dist. on Gertie. Worked for a time in the 80's for a very old Ford dealership in Bloomington, IN, and they had an old Sun stroboscope. We never used it anymore, as the newer electronic distributors did not need it. Was still working for the company when it was bought out. Old test equipment, like the Sun Stroboscope, and Sun Analyzer, were auctioned off for a song.

Speaking of distributor rebuilding, I have found that many of the parts necessary for a complete overhaul are still available, but have not seen any of the springs for the advance plate. Are these springs still available?

By the way, my dist. is the 7RA-12127.

 

Distributor Weight Spring (2) 7RA 13192

Dennis Carpenter (800) 476-9653 has 2

NOS LTD Waxahachie, TX (972) 937-2201 has 8

NOS Parts Warehouse Farmers Branch TX (888) 727-0418 has 4

Miller Obsolete Binghanton, NY (607) 722-5371 has 45

Bob Allen Ford Overland Park, KS (913) 381-2999 has 4

McDonald Obsolete Rockport, IN (812) 359-4965 has 1

There are also some on eBay.

 

Not sure you'd need the springs replaced, because they are adjustable. I've taken a couple dizzies apart, and what they really needed was a good cleaning. Crankcase oil climbs up to the bottom of the points plate, and not the clean crank oil. It turns to sludge and can make the points plate hard to rotate (for advance). Other than that, replacing the ground and hot wires under the plate is all they needed.

Taking the pin out of the drive gear is the hardest part of the job, and doing it without ruining the gear.

 

Thanks for the information Ross, and Harley.

I have had numerous distrib. apart over the years, so working on them doesn't faze me in the least. The thing that has always intrigued me, was the practice of setting a rebuilt distributor up on the stroboscope. I understand that the purpose was to properly set the advance curve, but over the years, I have never seen one actually strobed.

Do they really need it?

Back in the 80's I worked at four different dealers, two Chrysler, and two Ford. My area of expertise was body mechanical, driveability, heavy engine, and heavy manual transmission (the engine and tranny was referred to as "heavy" because I did complete removals, rebuilds, and installation). Not once did I ever use the strobe, and only rarely did I employ the Sun machine.

My gut feeling is that a good clean up of my distributor, along with new bushings, is all it really needs, and that it will work just fine. Still, I wonder if the curve will be off somewhat, and if the springs are properly set.

 

You can check the Load-a-Matic distributor on the truck pretty easily, and adjust it. You need to mark the crank pulley with adhesive tape to show degrees, which is easy enough. Then disconnect and plug the vacuum line at the distributor, and connect a hand vacuum pump (MityVac). The manual has the amount of advance you should get at various vacuum levels, and tells you how to adjust the spring tension if incorrect. Note the specs are in distributor degrees = 1/2 the crank degrees

Note also the carb needs to produce certain levels of vacuum for the distributor to function properly. Much harder to change.

A couple of local guys have distributor machines and use them to check their distributors. It's a much bigger deal on the front-mounted distributors on Fords.

 

What publication is that chart from Ross? There is a similar chart in the red service manual, but the data is divided by engine, not dist. model.

 

It's the Specs section at the back of the red workshop manual. I cut out the H and E series distributors.

 

Christ!
I found it. I was looking in the 1951 Supplement section.

Thanks for posting Ross, as always, it is much appreciated.

 

I have a Sun dist. machine as well as a couple of the big Sun tuneup machines.
The dist. machine is great for the front mount dist. on the older fords. I used it on my 46 mercury. I do not think it would help you, on a normally driven car or truck, to spend the time and money to have someone set up your later dist. on a machine. If you were doing high performance and wanted a specific advance at a certain RPM then yes it would help.
Larry

 

I've done both the early and late flathead distributors on a machine. One of the main benefits is checking the cam lobe accuracy, dwell variation, etc. It's also a whole lot easier to get the points aligned properly, both the rubbing block and the contacts. I agree that the machine is not a lot of help on the Load-A-Matic distributors. On the machines I used, you didn't have a fine enough adjustment in the vacuum source or enough resolution in the gauge for such small amounts of vacuum. In the chart Ross provided, I question the usefulness of the specs for the "distributor vacuum at the carburetor." That's not only dependent on the RPM, but also the throttle opening. For example, at 2200 RPM and full throttle (heavy load) there would be a lot less vacuum signal than at part throttle at the same RPM. - Bob

 

I could never figure that part either, Bob. If the carb was producing less vacuum than spec'd at RPM, what could you do about it anyway?!

 

Right, not much.

 

I've never tried to measure the vacuum signal at the carburetor - just always checked to make sure the vacuum advance diaphragm on the distributor had no leaks, that the fittings on the tubing were tight, and that the timing light showed the advance "working" when revved up a bit. Those specs for the vacuum at the carburetor at various RPM's would almost have to be running with "no load" - probably not many shops had chassis dynos or other means of applying a measurable load at that time. One thing I did find in the "red manual" are specs for the distributor vacuum ports in the carburetor and did some measuring while I had my carb apart this summer. - Bob