Flathead distributor "service"
 

Over the last three to four years we have made up and shipped well over 600 of the chevrolet conversion distributors to a happy group of flathead owners. (672 to be exact)
Over the years as we build these jewels we have made changes as we go along and its good to see one from time to time that has some serious miles on it.
These changes could be finish, paint , machine work , advance limits right down to the contact point attaching screws being switched to stainless ( i hate rust). The way we lube the parts have changed and for the most parts all the changes have been very minor in nature and most changes lately have been cosmetic just because i didnt like the look. Oh well its been a good design for the most part !!!
This unit came in today with some serious miles out of a flathead that the customer had broken something on the engine and wanted the distributor freshened up , recurved and tested for his new engine.
A couple notes based on what i seen when i opened the box...
The basic distributor looked very well, the advance weights still looked very new and the cosmetics looked good.
I noticed that the advance limit ( back then a rubber bushing---today we use a brass bushing) has swollen just from engine fumes etc and i replaced it with the new up graded brass piece. The advance curve was correct but it did change it a little on the lower end and took a couple degrees out of the top end.
The biggest no-no i seen was the primary lead going to the points was cut and a new end crimped on ( see pic) oops that one i hadnt thought about.
I realize why you would neaten up the primary lead but ya can do that !!! The lead is a factory calibrated lead to drop the final little surge of voltage going to the ignition contacts after the coil drops and consumes the final shot of voltage...
We suggest using a 1.5 ohm coil and a 1.5 ohm resistor on 12 volt systems. Using ohms law with 3 ohms resistance and a 12 volt battery would equal 4 amps current flow in the primary ignition system. ( perfect for this system)
Voltage drop is ohms times amps so each would drop 6 volts in a perfect world and the voltage would be zero or close to it at the contact points ( actually approx .100 mili volts etc).
This works well untill you start the engine. Two issues here as the voltage usually goes up to 14 volts and the resistors heat up. This allows the voltage in the calibrated primary lead to increase slightly. The calibrated (finely stranded) lead is our final resistor and consumes the final voltage drop eating up this excess protecting the points.
Its not uncommon to see a street roder replace the engtire lead with solid 14 gauge wire !!!! Bad move for sure.
Moral of the story is "DONT CUT THE FACTORY PRIMARY LEAD ", We install this factory lead for a reason...:eek:

Item two is the condition of the contacts with some metal transfer , again pretty normal but maybe a little pre-mature on the example used with cut primary lead.

It changes the capacitance in the system.......clear enough...:eek::D????

Re: Flathead distributor "service"
 

Good to hear of an "experienced" distributor coming back for some updating/freshing and appearing so good as it came back. Around here we use a vw coil with internal resistor as oppossed to a external type-Any thoughts on that? I want to have a conversion done for my engine-what do I need to do? 51 Merc with a 77b Isky cam

Re: Flathead distributor "service"
 

so i could install one of those resistive primary leads and get rid of my clunky external 1.5 ohm resistor? if so, sign me up...jack

Re: Flathead distributor "service"
 

Didn't know the lead was resistance wire or that it was calibrated. What I learned today. Thanks, Jim.

Re: Flathead distributor "service"
 

Nope the final lead is used with the resistor............

Re: Flathead distributor "service"
 

The Bosch blue could be the best coil ever made !!!!! I use them on many projects.....

I have your conversion in stock just call to order....317-487-9460 Ask for the flathead conversion with points etc.......

Re: Flathead distributor "service"
 

Good Post Bubba !!!!!!!! Good point about distributor lead.
;)

Re: Flathead distributor "service"
 

if i read the final lead with a ohmeter, what should the resistance be? thanks...jack

Re: Flathead distributor "service"
 

Jack, Not sure it would be measurable without a load on it. They are a finely stranded wire that would only offer resistance when current was flowing through and the voltage level was higher than normal...
Most auto parts stores sell these special primary leads for different applications. I stock a GM lead and a Ford ( later model ) lead ..

Re: Flathead distributor "service"
 

Bubba
It looks like a Flathead dist,
does it use same rotor and ford cap.
Do you need a core or sold as is without one.
Do you have straight axle on your F1,my 52 f1 does,nt like more then 55mph.
I,d have to do something to make 100 MPH.

Re: Flathead distributor "service"
 

I like the idea of the Chev dist. The hei style is so large and out of place looking on a stockish flathead. Would a points style and msd box be a good way of going eletronic but more hidden. I want to use a duel intake I have and the stock dist. with petronics still has only the vacume advance? Your opinion is god here:D

Re: Flathead distributor "service"
 

Our flathead conversions use a delco distributor cap and rotor and no core is needed.

We made a tube axle for the truck an actually narrowed it a bit to tuck the tires in per air testing etc. We have ran 108 with the truck but caught the wrong fuel last weekend.....

Re: Flathead distributor "service"
 

" friends dont let friends use MSD" :D

Ok just kidding , however the design and the compression ratio of the flathead doesnt really need the features a MSD box can bring. The point distributor with a MSD box would run forever and the MSD box would take the load (amps ) of the system very well. Good idea...

Replacing the stock loadamatic is a must do !!

Re: Flathead distributor "service"
 

Thanks for your reply. Just thought the smaller dist. and cap on the points set up would be less conspicuous. Now how are the points style for availability and how much do you charge for one and is a core exchange needed?

Re: Flathead distributor "service"
 

No core required, Conversion is $180 complete with cap, rotor, and resistor.
You can call the shop at 1-317-487-9460

Re: Flathead distributor "service"
 

Sounds great I will be intouch soon thanks Brad

Re: Flathead distributor "service"
 

I installed one of your conversions but due to that ugly thing called "work" haven't driven it much-took a 35 mile highway trip to see a buddy and it ran great, really big difference in top end pick-up, and smoothness. Thanks I have one question-what do you think the coil temperature should be? More of an knowledge based question than a concern. If you are an older person you might remember Manard G. Greebs on Doby Gillis and his refernce to "work"

Re: Flathead distributor "service"
 

Using a 1.5 ohm resistor and a 1.5 ohm coil it shouldnt get very hot at all. Maybe warm underhood but not boiling hot.
If the coil has less resistance then expect it to get hot.
Been having a terrible time with some of the aftermarket off shore ignition coils.... :eek:

Re: Flathead distributor "service"
 

Bubba i used a Blue Bosch on a 1 cyl. Royal Enfield i had a couple of yrs ago. Fantastic coil. Bike ran like a scalled dog.ken ct.:)

Re: Flathead distributor "service"
 

Ken , The blue bosch ( vw beetle) coil is a 3-4 ohm internally resisted ignition coil and one of the best out there . Good choice for a coil...

Re: Flathead distributor "service"
 

If you use the Bosch blue coil do I still also need to use the resistor that you provide with the chev dist conversion. Thanks Jim

Re: Flathead distributor "service"
 

No resistor is needed with the bosch blue coil....

Re: Flathead distributor "service"
 

Bubba, do you have a part number for the blue coil?
also, how much to rebuild a stock distributor on a 51 Merc? I'll be running a 12V system
Thanks!

Re: Flathead distributor "service"
 

Looks like the coil number is 0-221-119-027 we get them from a off road VW dealer here in town for $40-$50 each........

Re: Flathead distributor "service"
 

Bosch says the blue coil is for 4 and 6 cylinder engines.
Red coil for 8cyl.
Red one needs a resistor

I always use the blue one......
My 276ci sees 5K rpm not often but, the blue coil still fires the spark plug ok,
no problem there.

Maybe Bubba can explain when you need which coil, but
i think blue is all you need

A 6cly engine at 8K rpm
and a 8cyl. at 6K rpm
have the same cycles per minute

an who revs his Flathead to 6K ????

Re: Flathead distributor "service"
 

Re: Flathead distributor "service"
 

As mentioned above the Bosch Blue coil was made for 4 and 6cylinder engines based on ramp ( coil build up time) and overall rpm ranges etc. However with the flatheads rpm band the bosch blue works very well.
The key is having the correct primary ignition resistance. Coils have got pretty bad in quality over the last few years with many companys buying off shore stuff that doesnt seem to hold up well with the heat, but in their defense its usually a misapplication that causes the problems.
Most of the time when someone walks into the shop with a fryed coil its the wrong coil for the application purchased at a swap meet or a buddys garage.
The 12 volt ignition system needs approx 3-4 ohms of primary resistance to maintain a current flow of 3-4 amps to keep everything working for many happy miles . A electronic system usually is higher amps and lower resistance.
We have a coil made for us ( USA made) in Layafette Indiana thats oil filled and is a very good quality. Costs a little more but very seldom do we have a return.

Another tip is that spark plug gap goes with the engine and combustion chamber NOT the ignition system. A wide gap and hotter spark is seldom needed in a flathead application...

Re: Flathead distributor "service"
 

I would suggest the Bosch blue for a 6 volt system with no resistor needed....

Re: Flathead distributor "service"
 

Bubba, I'm running a light brown Bosch coil I got off a 72 Fiat years ago. It's marked 12volt, so I hooked it up with no resistor. I'm running a Mallory dual point converted to electronic. It works great so far. Can I do the same with one of your Chevy's converted to electronic?
Butch

Re: Flathead distributor "service"
 

I would think so..

Re: Flathead distributor "service"
 

Bubba, I received your dist. last week, it looks great ! I'm taking your advice and buying a Bosch Blue coil. My question is kinda simple for some but can I paint it black ? Don't want a blue coil, if yes could I use my favorite Krylon 1613 on it or what ? Thanks. CBN

Re: Flathead distributor "service"
 

Sure , but i would prefer "elvis gold" i think.........:eek::D

Re: Flathead distributor "service"
 

Re: Flathead distributor "service"
 

"The blue bosch ( vw beetle) coil is a 3-4 ohm internally resisted ignition coil and one of the best out there . Good choice for a coil..."

"As mentioned above the Bosch Blue coil was made for 4 and 6cylinder engines based on ramp ( coil build up time) and overall rpm ranges etc. However with the flatheads rpm band the bosch blue works very well. The key is having the correct primary ignition resistance. The 12 volt ignition system needs approx 3-4 ohms of primary resistance to maintain a current flow of 3-4 amps to keep everything working for many happy miles . A electronic system usually is higher amps and lower resistance."

I am confused as to what Bubba is saying. Please clear me up. Above he says to use a 1.5 ohm primary resistance coil then later in the post he recommends the Bosch 3.4 ohm primary resistance coil (part 0-221-119-027).

Another thing confusing me is where he is talking about the primary ignition resistance and not needing an external resister with the blue Bosch coil. Is he talking about the ballast resister? Is it a 1.5 ballast resisiter he ships with his GM conversion points distributor?

Thanks ahead of time for any clarification help provided. Bubba if you answer this yourself I am referring to you in a third party in case you don't see this post.

Re: Flathead distributor "service"
 

We typically want approx 3 ohms resistance in the primary of a 12 volt point type of ignition.

One way to get that ressitance is to use a 1.5 ohm coil and a 1.5 ohm resisitor for a total of 3.0 ohms or 4 amps in the circuit. ( We ship this resistor with our units as many have had trouble getting them )

Another way to get this is to use the Bosch blue coil at 3 ohms as well.
The actual rpm band of the flathead works very well either way....:eek::D

Re: Flathead distributor "service"
 

Just read this post, and now I'm going to get yelled at.
I'm putting all cloth wiring in my car, from RI wiring, and in the process of doing so I took out the dist primary wire and out a cloth covered 14 ga wire.
I did not know that was so critical. Now I have to see if I can find the one I took out, or I can grovel and see if I can get Bubba to send another.:o

Re: Flathead distributor "service"
 

I have never cared for the coil mount on the 8ba cylinder head, I feel it's clunky and crowded. I just finished building a new engine for my f1, (maiden voyage was sunday actually). Anyhow, I fabricated a new coil mount that attaches to the inner fender, to clean up the cylinder head area. I have one of your distributors in my engine, the lead was not long enough to reach my new coil mounting position. Since I did not know any better until I saw this, I cut and spliced the lead and covered it with asphalt wire cover. I'm happy to get a new bosch blue coil, but my question is, do I need to replace the lead with a longer one of the same type, or different gage as the length is different? Also if I use the bosch blue, do I need to remove anything from the distributor?(resistor?)

Thanks.
Matt.

Re: Flathead distributor "service"
 

Re: Flathead distributor "service"
 

Leave the lead in place as final resistor and extend if needed . Shouldnt need a resistor with the Bosch blue...

Re: Flathead distributor "service"
 

this one ............
http://www.summitracing.com/parts/bch-00012/overview/