8ba distributor questions

GB SISSON

GB SISSON

Well-known member
My recently completed 276 8BA engine is running great and because of that we are planning some road trips. I am putting together a kit of spares which would be at least another distributor and carb. I have a few extra of each. This morning I cleaned up a nice 7RA distributor and started looking at points and condensors in my box of ignition parts. I am running a nippon-denso condensor from a toyota in my 276 now and found another in my landcruiser stash. So now I have the distributor in the vice and a good battery alongside with a napa 12 v coil with internal resistor and wired for negative ground. Tt easily throws a hot blue spark 1/2". Pretty loud snap too. But I noticed it arcs across the points as I rotate the gear. With a clean spark plug instead of the 1/2" gap it still arcs at the points, but way less. I tried other condensors, still the same. Then different points with no change. Lastly I tested a never installed NOS 7RA distributor with the same results. Having not worked on distributors out of the car much, I'm going to assume that this is normal and the condensor will do it's job keeping the points from pitting. Unless I'm missing something. I have a few more questions.
1) How do I remove the breaker plate for further cleaning and inspection?
2) On my installed 8BA the old vac unit advances the timing visibly (shown with my timing light) and with the hose in my mouth I can easily see the breaker plate moving with the cap off. It advances while steady suction but the suction has to be ongoing as it will not hold. The NOS vac unit and the napa unit both hold suction indefinately. I would ask the panel of experts, Which one of these two would you trust the most on my primary distributor? One is made overseas and one is unused but 70 years old. Thanks, GB
 
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cadillac512 said:
The sparking at the points is normal. I'd run the NOS vac can. It'll be calibrated correctly and I'd just take the chance if it were me.
As for disassembly...I don't have the answer. I've not taken a Loadamatic distributor apart. I do have one around here someplace though. Below is a link to an exploded viewof the distributor thanks to Mac VanPelt.


http://www.vanpeltsales.com/FH_web/FH_images/FH_engine-pics/Flathead_Distributor_1949to50.jpg
Click to expand...

Thank you Terry, That helps a lot! I'll look at the link. Edit: I think I'll go on the assumption that one has to drive out the pin and pull the gear and pull the shaft out.
 
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I have never encountered an 8BA distributor with worn bushings that I thought needed to be taken apart. I soak / spray them clean, oil them up, and go again. I am sure there is a worn out 8BA distributor out there but I haven't run across it. I would not trust old rubber in an NOS diaphragm. There is no calibration to the 8BA vacuum diaphragms, the calibration is done by the springs on the point plate. The diaphragm that will not hold vacuum is bad and needs to be replaced.
Be careful of new diaphragms, I have seen several where the hole for the vacuum line was not deep enough and tightening the Ford Nut would pull the vacuum line through the nut.
 
While trying to isolate another problem, I disconnected the vacuum to the advance on an 8BA distributor and set the static timing to 10 or 12 degrees BTDC. The car ran great and I couldn't tell any difference by seat of the pants feel. I tried it a little higher and get some kick-back on the starter. I'm sure there would be some efficiency loss, but an easy adjustment to get you to a place for a proper repair.
 
While tuning this non-stock engine I'd put together, I gave serious thought to a Model A style timing lever in the cab. It would be fun to experiment with but if for some reason somebody else ever drove it there could be trouble.
 
A lot of the modern replacement condensers are crap right out of the box. It takes a relatively sophisticated test unit to check a condenser for capacity, leakage, and resistance so I generally purchase two or three at a time. I've used the Echlin brand for a long time and had good results but they were bought out by Standard Motor Parts some years back so I don't know anymore about how they will hold up.

The condenser has to be able to absorb the back flow from the coil during an induction event. It can be up to around 200 volts. This is why the condenser is there. If it doesn't do a good job then the breaker points will suffer. It's not unusual to observe a little bit of arcing at the points during a test but it should be minimal. The system will still function with a degraded condenser but damage to the points will eventually ruin them.
 
I have at least ten condensors here, primarily from these 7ra distributors. Using my non-scientific visible arc test, I have found both of the japanese made toyota landcruiser (.022 mfd) show the least arcing at the points. All of them allow a hot blue spark that easily jumps my 1/2" test gap. I only do a very brief test with this gap as I don't want to overstress any component. Then I switch to a new spark plug with a .030 gap and dim the lights. Five of these condensors show a bright arc at the points. Quite visible with all the lights on. The rest were as follows Two unbranded with a separate mounting band and a red wire, stamped made in USA showed arcing at the points only visible with lights dimmed, the NOS distributor with it's Ford oval on the condensor about the same. The nippondenso condensors both got the highest rating. I needed to cup my hand around the distributor and spin the gear while peering through my thumb and forefinger like a microscope, and yes then I could see a steady and predictable light arcing as the points opened.
I bought my first toyota pickup at age 20 in 1973 during the 'energy crisis', considering it a throw away truck. My previous transportation had been a '28 AA flatbed. 20 years later the toyota was still my DD, but my love for old Ford trucks never died.
 
I installed the new napa vac advance can on my 'backup distributor' and when I hooked up the timing light and blipped the throttle I could see the action was considerably better than what I'd been seeing. Now the backup is my keeper and the other one goes in my emergency spares kit. Without a vehicle to drag outa the woods this winter, or an engine, transmission or transfer case to overhaul, I just might finally get bored. I can envision an arm off the distributor with a ball end, this arm fastened by the same screws that secure the vac advance can, then and a choke rod off the arm coming through the dash. I can also imagine a vacuum gauge in the cab which might help me see the results of timing adjustments on the fly. I currently have a vintage Allstate vacuum gauge mounted on the firewall for under the hood tests. Then there's the new intake manifold I want to build with enlarged ports for the 2110 carb I'm running....
 
This is a bit of a stretch but many years ago there was a feature called Gus's Model Garage in Popular Science or Mechanics IIRC. One article was about an old hearse that was hard to start. "Gus" modified the distributor so that it could be retarded from the front seat using a rod attached to the body of the distributor. To start the car the rod was pulled to allow the car to start and then pushed forward to advance the distributor and lock it into position with a notch in the rod. The exact details are more than fuzzy since I read the article well over 50 years ago. Looking forward to reports of your modifications.
 
There are two different ways to approach this. Keeping the distributor stationary and having the rod (or cable) attached to an arm on the breaker plate (model A style), or rotating the whole distributor. The latter would have the advantage of being able to keep the vac advance hooked up. If I was REALLY bored I'd install a valve in the vacuum line to disable the vac advance when I desired to go full manual. This valve would of course have it's own control rod within the cab.
 
GB SISSON said:
There are two different ways to approach this. Keeping the distributor stationary and having the rod (or cable) attached to an arm on the breaker plate (model A style), or rotating the whole distributor. The latter would have the advantage of being able to keep the vac advance hooked up. If I was REALLY bored I'd install a valve in the vacuum line to disable the vac advance when I desired to go full manual. This valve would of course have it's own control rod within the cab.
Click to expand...


For a guy who originally wasn't concerned with more power you sure seem to be embracing it. :D If you go to 'sperimenting with altered states of timing don't forget a ground wire to the fancy moveable distributor. ;)
 
HaHa Terry, the hotrod guys haven't converted me yet. I just have an inquizative nature. Starting with my 200.00 1960 bug in 1969 I would set the timing by ear at idle and be done with it. That method was used for almost 50 years, never a thought to advance working or not, how many degrees this or that and what is 'dwell' anyhow. Installed many carb kits in all manner of single and two barrel carbs, yet never swapped out a jet or even looked for a number on one. I never owned or used a timing light unti about 2019 when I bought a 1960's looking craftsman at a yard sale for 3 bucks. Now with these flathead fords most of mine have been the early front mount distributor and I never messed with them, they were too mysterious with their vacuum brake and dual points, not to mention their rather boring fixed position and horrible access. Because of this I just sent them out to the experts and kept a spare. I have also noted with our V8s that when at temp, some start up with the quickest tap of the start button (I love that) and some crank a little bit. What made the good ones so good?
Some of you may recall my quest for answers over the years and all the home built testing devices I have come up with to satisfy this need. My block pressure test apparatus with the open cylinder plate made from some kitchen countertop material, the purpose built horseshoe electromagnet for magnafluxing, the oil pump tester driven by a 12 pt socket in a drill, valve spring tester made from a wheel cylinder, 60 inch/lb adjustable lifter tester to name a few. Hotrod or not, I just want my V8 that I invested a whole winter in to be the best work that I can do, and to know that when I have 5 short body oil pumps to choose from, I can know I'm getting the best one. Besides, I live in the middle of nowhere and if I didn't tinker with this s#!+ I may spiral into boredom! :)
 
After reading GB's last rant, and knowing GB, from years of posting his adventures, to picture the movable distributor one would normally say we are thinking outside the box.

In this case, Gb probably made the box, out of wood of coarse, and is thinking inside his own box. So, in this case, I suggest a cable wrapped around the dizzy, on to a shaft, like a kids go cart steering, , thru the fire wall, under the dash (less damage) and a wood workers knob with a back board with indicators on it made of wood of coarse. White oak, scarce on the island, but I can snd you some if you wish. perhaps a piece of mahogany off the scraps at the boat yard next door. just some thoughts here...carry on
 
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