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November 2019
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Kirkham Motorsports

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  • 1 Post By Bobcat
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  #1 (permalink)  
Old 07-12-2019, 01:03 PM
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Default Duraspark in place of MSD mechanical

Since I`m not tracking the car much now , trying to make it more streetable. Changed the shock valving and all coil springs .

Decided to go to a VA recurved Duraspark in place of the MSD mechanical advance unit . Can`t complain about the MSD unit .... 10 years and only replaced one cap ( almost 10,000 miles ) .

The MSD doesn`t require a resistor ..... does anyone know if the Duraspark unit does ? I`ve got one , but don`t want to put it in the circuit if it`s not needed.

thanks
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Old 07-12-2019, 08:38 PM
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Are you going to use an MSD box or Ford unit with the Duraspark distributor?

I don't think you will need a resistor with the Duraspark. I have a MSD 6A with a Duraspark in my '66 Fairlane, no resistor.

I'm building a '68 Fastback for a guy. It has a 428 with Duraspark and MSD 6AL. He had the motor build by a Ford FE specialist. No resistor.

I've looked at several wiring diagrams on both car and have not seen a resistor in the circuits.

Maybe someone who really know will post.

This post caught my attention because I took three Duraspark distributors apart today.
I'm trying to recurve the one on my Fairlane. And adjust the vacuum advance.
I had a question about the bushing on the pin to limit the total advance. I removed parts on the 68 Fastback distributor so I could see the pin. I bend one of the springs so I will have to replace it. Called a buddy and he said he has one. Lucky me.

I've learned a lot about Duraspark today. I do like them.

good article on tuning Duraspark

The Ultimate Duraspark Distributor Timing Guide.
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Old 07-12-2019, 08:42 PM
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Quote:
Originally Posted by Bobcat View Post
Since I`m not tracking the car much now , trying to make it more streetable. Changed the shock valving and all coil springs .

Decided to go to a VA recurved Duraspark in place of the MSD mechanical advance unit . Can`t complain about the MSD unit .... 10 years and only replaced one cap ( almost 10,000 miles ) .

The MSD doesn`t require a resistor ..... does anyone know if the Duraspark unit does ? I`ve got one , but don`t want to put it in the circuit if it`s not needed.

thanks
It depends...

IF the coil has .08 primary ohms or less, then it will need a ballast resistor for continuous running; for drag racing, short term usage, usually not.
Now if the coil has .14 primary ohms or more then it would not need a ballast resistor at any time.

Does this Duraspark wiring need the ballast resistor?

If the original Duraspark II coil is to be used, it needs to be supplied with about 9 VDC, not full battery current. That means a ballast resistor or resistor wire needs to be used. Optionally, a different coil that can use 12 VDC can be substituted for the DS II coil. Many aftermarket performance oriented coils work fine with a Duraspark setup. The Duraspark II module (blue strain relief) needs full battery voltage.
https://www.crankshaftcoalition.com/...spark_ignition

Break out the VOM.
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Old 07-13-2019, 10:42 AM
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Thanks for the info .... the distributor has the blue module and was recurved by Faron Rhoads in PA who does a lot of these .

Specs are : 8 degrees in the distributor , all in by 2750 . VA adds another 10 degrees starting at 11" up to 17 " . Initial will be around 20 degrees which should give a total at WOT ( no vacuum ) of 36 to 37 degrees. I normally set the max advance ( allowing for the MSD retard of a few degrees at 3000 rpm .... I go to 3500 rpm ) and then modify the initial if not high enough .

I should have been more clear ... MSD box is a 6 AL and the coil is a Ford HEI , E core . I`ll measure it today and if too low , I`ve got the MSD and accel coils in the garage also .

Hoping this will make it a little more streetable at low throttle openings /higher vacuum in traffic .
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Old 07-13-2019, 01:09 PM
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Just did a re read of the link on ballast resistors and Durasparks . It said the standard Ford E coil has a resistance of 0.5 ohms and .14 ohms is needed . Also said further down to just add a .85 ohm resistor . My math says 0.5 and .85 = 1.35 ohms , not .14ohms .... slipped decimal place maybe ?

Unfortunately my meter`s lowest scale is 200 ohms , so measuring 1.4 or .5 is really suspect to me .

Anyway , I have the blue module and the guy who did the distributor said no resistor is needed , Guess I`ll find out .
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Old 07-15-2019, 06:58 PM
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I use the MSD 6A and the MSD Blaster coil and the Duraspark distributor. I have had the car on the road for 26 years. No resistor.
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