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DUI dist won't fit

3K views 10 replies 6 participants last post by  spectralen 
#1 ·
I recently pulled the recurred Duraspark to replace it with a DUI and it won't fit. I've had two MSD 6al boxes go bad in the last two years, so I yanked all the MSD stuff and decided to replace with a DUI. I bought the special thermostat housing to clear, but the dist won't go the last 1/8 inch even without a housing in there. Anybody have any ideas? It's a Ford motorsports driveshaft. First chance I get I'm gonna remove the oil pump driveshaft to see if dist fits without it. It's just that the Duraspark fit fine.
 
#2 ·
You didn't tap on the oil pump driveshaft end of the distributor with a hammer to remove a steel cam gear did you?

I've had the oil pump drive shaft flop over and lay on the side wall of what the distributor slides down into. I have an oil pump priming tool that I will use to turn the oil pump driveshaft a little bit when this happens and then it will slide down in. Either that or the oil pump driveshaft & cam gear are just slightly misaligned compared to the old distributor and you get stuck on the top of the oil pump driveshaft. Again an oil pump priming tool to slightly rotate the oil pump driveshaft cures this problem.

Those are my only thoughts on it.
 
#3 ·
I think (will find out tom) it was the o-ring. My buddy had similar prob and he just changed o-ring. I took o-ring off Duraspark dist and swapped on DUI (with no driveshaft) and it fit. Put rtv in dist, will let dry overnight, and find out tom afternoon. It fit w/o driveshaft so we will see.
 
#4 ·
It still won't fit. It fits w/o driveshaft, so I ground of ~1/8" and no change. So it seems to be driveshaft "shoulders" where it goes from round to hex. So I'm thinking I should order a stock replacement and see if that fits.
 
#5 ·
Well I got a stock replacement Melling (all hex), and it fits. I still had to grind on the thermostat housing (indented to supposedly clear) to clear, but now everything fits right.
 
#6 ·
The clipped thermostat housing is designed so the large cap and cap a dapt d/s distributor clear not a DUI / HEI gm style distributor.

Oddly enough I have been using MSD ignitions for over 15 years and yet to have one fail. I can count the number of D/S distributors I have had to replace due to failure on 1 hand. This out of thousands sold.




S
 
#7 ·
I bought the indented thermostat housing from the DUI people to work with the dist, but maybe it was originally for a cap-adapt. The first MSD box was probably from welding on the truck, but the second was from no apparent reason. I just went with the DUI to have less parts; no external coil, no ign box, less wiring.
 
#8 ·
I have had a Jacobs Box and coil for 20 years no problem and I've welded all over my truck with it hooked up. To each his own I guess DUI box is Chevy top Ford bottom and you say the top part won't fit why because it's a Chevy part that's why sorry just joking with you I couldn't resist hope you get it to fit worst case buy a alum one then you can weld on it and make it work that way good luck
 
#9 ·
I'm running a Jacobs system on my hauler as well as the race car and have had ZERO problems. Too bad the're not around anymore.
 
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