Holley/Duraspark Distr conversion-Carb/EFI (SAVE $500)

[Bill USN-1]

This conversion is very simple to perform. I started this when I had my first "Gold Box" go bad. I wanted a system a little more avail in the local parts store. I have made several changes over the years to the original conversion and for the non-FI crowd, there is even an easier system to use with this distr conversion.

Here's a little video to show how the system works. This is one for a carb and I used the electronic ignition round coil with .7 ohms resistance.
This conversion can save you over $500 when compared to the large cap HEI distributors being sold for the IH. This just happens to be the DIY/poor mans version but it works the same and uses the same ignition module.


Duraspark conversion video


Before you run to the junkyard, read this post to decide on ignition parts!!!
The preferred ignition is the GM 4 pin module for carbs and the GM 8 pin module for EFI
CLICK

The first thing you need for this conversion is the right IH distr.
I have only done this on the Holley distributors. They can be points or GB, and can be 4 or 8 cyl.

For FI conversion only
For non-FI conversion
For both- normal

Then you will need a couple parts from a donor Ford Duraspark dist.
There are 3 things you need.
1. The base plate. Used from a junkyard. Normally $5.

2. The reluctor. (I buy new)
Part Number: EL205
For Your Vehicle
Vehicle: 1979 FORD F-150 PICKUP
Engine: V8 5.8 Liter 2BBL
351M Eng.; 351W Eng.
Our Price: $3.97

3. The magnetic pick up. (I buy new)
Part Number: EL307
For Your Vehicle
Vehicle: 1979 FORD F-150 PICKUP
Engine: V8 5.8 Liter 2BBL
Pick-up: 351M/W
Our Price: $19.48

Or Part Number...Wells parts were a little cheaper and are supposed to be pretty good quality.

Since I have not found a part number for the Base plate, I go to the local junk yard. While I am there I try to pick up a couple just in case some other binder nut wants to do the conversion also.

This is what the Ford Duraspark distr looks like.

To get to this, you just pop the clips off the cap and set it aside,

then pull the rotor off the center.

Now to get to the base plate you have to remove the reluctor. and vacuum advance. Just remove the 2 screws on the advance and the small clip that holds the arm on the base plate(if it has one).

Just use a couple of large screwdrivers and carefully pry up on the center from the bottom. Do not pry on the the fins!!!

Now just remove the 2 phillips screws and lift the plate out.

This is what it looks like.

Now to replace the pick up module.
Just remove the small snapring in the center and lift it off.

(Up to this point is what I do while at the junk yard. That way I only pay for the part I need.!!!)

Back at home..........


Grab either your points distr or your Gold box distr and remove the 2 screws holding the vacuum advance on and the clip on the arm. Once off, then remove the 2 screws holding the plate in the distr.

Here's what the bare holley plates look like.

Note the mounting holes are slots.
Now set the old plate on top of the Duraspark(DS) plate and line up one of the slots with a mounting hole in the DS plate.
The other one won't line up.

What I do is just grab my cut off wheel and make a new slot in the DS plate to match the Holley mounting slots.
You can also just mark it and use a drill.

NOTE the difference in the size of the center holes in the plate!!!

Here's how it looks in the distr. (you won't be able to do this yet) But note how close the shaft runs inside the new DS plate!!

 

[Bill USN-1]

Re: Holley/Duraspark Distr conversion-Carb/EFI

Next you need to remove the advance shaft off the main shaft.
Look in the top of the shaft and remove the piece of felt.

Now you will find a little 3 prong clip down inside. Sometimes these come out very easy, sometimes you put money in the cuss word jar!!!
I try to use a couple of dental tools or scribes or jewelers screw drivers to carfully remove them. Don't force it and try not to break it.

Once it is out, the shaft will slide right off the top. See those little green bushings....pull those off and set them somewhere safe.

For the Gold box (GB) shaft, you need to remove the original reluctor wheel.
I just set the shaft in a vice loose so the fins of the reluctor are setting on the top of the vice. Then I use a small block of wood and knock the shaft down through the reluctor.

Now comes the fun part!!!!!
You need to make the shaft small enough to fit thru the smaller hole in the DS plate. And it has to rotate with out hitting.

For the GB shaft this is real quick and easy! Just smooth out the rough casting that was below the reluctor. There should already be a machined lip where the old reluctor was.

For the points shaft this will take a few minutes.

A couple very important things to know.
1. Grind the lobes of the shaft down to about .050" or less diameter larger than the rest of the shaft.
2. You need a small lip for the new reluctor to set on.
3. Keep a small cup or coffee can of water next to the grinder to keep the shaft cool! (you will need it)
4. Do not grind the shaft where the reluctor will set or it will not run true.

OK...anybody have any fingers left?

For Computer controlled timing

You will need to disable the mechanical advance.
This is simple by just removing the springs and weights that are on the main shaft.
Then I slip the adv shaft back on and place each leg between the spring retainers and and the weight mounts. I use a pair of pliars to bend the spring retainers tight against the shaft. Since there is no wear on parts, these will hold the shaft in place. But if you want extra security there are two other options.
1. Place a small spot weld on each leg of the shaft.
2. Place a small spot weld right in the very top of the shaft where the clip goes. Either will make the shaft mount permanent.

For Carb- install the advance shaft back into the distr just like it came out. Don't forget the green bushings.
NOTE: I did NOT remove the springs or fly weights. If you do then they must go back in exactly like they came out or you will change the mechanical adv curve of the distr. There should be slight tension on the light spring and the heavy spring will move free for about 1/2 it's loop on the end.

Now place the DS base plate into the distr and install the mounting screws.

Now slip the new pick up on and put the snap ring back on.

Install the vacuum advance and connect the arm to the magnetic pick up.

For EFI I still put the vacuum adv back on to position the adv plate and hold it in place. That's all it does.
You do not hook the vacuum line back up!!!

You could put the advance arm on then drill a hole and stick a screw thru to hold the plate in position. Then remove the advance and seal up the hole!!!

Now you need to make a slot for the wire harness. You may be able to just extend the slot from the GB wires.
After I measure where the slot needs to be so it will let the wires lay flat around the inside of the distr without rubbing anything, I cut a vertical slot just big enough for the grommet to fit in. The ground tab should almost be flat on the plate and the top of the grommet flush with the top of the distr.
You could use a hack saw for this also.
For the points distr, I just use a small dab of silicone to fill in the original hole the wire went thru.

Once in place, you need to drill a small hole for the grounding tab inside the distr. You can put the screw in either hole in the tab.

Now the last thing you need to do is set the reluctor/rotor.
I normally set the reluctor upside down so the longer part of the fins is down. It seems to cover the whole length of the pick up better. (opposite of the pics!)
I like to use an old distr cap to help set the position.
I just drill a hole between the spark plug wire terminal and the coil wire terminal. About 1/2" diameter.

For EFI set the rotor so it is pointing just CW of the center of the terminal.
(The picture is slightly exaggerated.) I set the rotor so the corner of the rotor contact is right at the trailing edge corner of the cap terminal.
Keep in mind the rotor turns CW so you want it to be just before it rotates past the cap terminal. This allows it to sweep back across as the timing is advanced.


For carbs the mechanical and vacuum advance move to advance the timing so the rotor should be centered on the cap terminal


Then pull the cap and line the reluctor up centered on the pick up.
Do not move the shaft/rotor while setting the reluctor.

Now as before , you have 2 choices on how to lock down the reluctor.

1. What I used to do, before I installed the reluctor, was drill the reluctor between the fins and tap it for a set screw. About a 4-40 screw. Make sure it is short enough to not stick out and cause a false signal to the pick up. About 3/16-1/14"

OR...What I do now!!

2. Just place a couple drops of locktite at the shaft and reluctor, then use a center punch and stake the reluctor and shaft where they meet. I only do 2 stakes on opposite sides of the shaft.
There is no wearing parts so I have never had one come loose either way.

Now your done.

OH....Did you put the clip back in the top of the shaft????????
Did you spin it to make sure it spins free and doesn't rub?

But wait...
what about the 4 cyl guys????

Here's all you need to do different!!!
Take the 8 cyl reluctor and remove every other fin!!!

 

[Bill USN-1]

Re: Holley/Duraspark Distr conversion-Carb/EFI

Here are an example how Dave mounted the GM ignition module and optional coil for the conversion. See ignition FAQ.
When mounting on a flat sheet there are alignment buttons on the bottom of the module. You need to remove these with a razor or drill coresponding holes in the plate. Always use some thermal compound between them.
Like what you use to mount fans on top of PC processors.
You have to conduct heat away form the module and provide good grounds through the mounting screws.

Dave Clifton

And here's a little video to show how the system works. This is one for a carb and I used the electronic ignition round coil with .7 ohms resistance.
This conversion can save you over $500 when compared to the large cap HEI distributors being sold for the IH. This just happens to be the DIY/poor mans version but it works the same and uses the same ignition module.


Duraspark conversion video

 

[Clunky Crawler]

THANK YOU THANK YOU! This info was SO helpful to me. This option was the best price/performance/ease to work on(once holley GB distrib converted to duraspark)