New vs. Old Style Duraspark

[Nathan in MI]

Oky doky, that's what I'll go with, then. Thanks guys!

[Tiggie]

To kind of go against the crowd here, I wanna say that the newer Duraspark will be fine without all the other inputs. Of course, I don't have any evidence yet to prove that. I'll look at my service manuals when I get home on Saturday.

The MCU basically controls one thing... the fuel mixture. I've ran my car without the MCU even hooked up (it has the 3-connector Duraspark Box). It ran rich, but not funky like it taking timing out or something. Of course, the 351W MCU's had an added function, a knock sensor input to tell it to retard the timing. So the 351W MCU and Duraspark are related now that I think about it.

But it might not be related as so to mess up much. My car does have the high altitude package, and is supposed to have an altitude sensor, which tells the Duraspark box when to advance/retard the timing. It doesn't have the altitude sensor (cut out somewhere in the early years of the car) and the timing never jumps around.

The problem showed itself when I checked the timing, it is at 8 degrees BTDC (factory setting for my car), with the vacuum advance pretty much as far as it will go against the thermostat housing. Either someone has installed my distributor a tooth off at one point, or the Duraspark is taking timing out due to the altitude sensor being gone.

At the same time, I am running a 351W MCU on my 302 car. It could be the fact that the 351W MCU is looking for that input from the knock sensor and taking the timing out through the Duraspark box.

So I think I have offically made this more confusing. I guess the conclusion I have come to is the newer Duraspark box will work without the MCU, but may retard the timing. Or it might not retard the timing, my distributor could just be a notch off.

My advise to you Nathan is too unhook your MCU and check the timing. She's gonna run a little rich while it is unplugged, but it won't hurt anything.

[Nathan in MI]

I have no doubt that the car would still run without the MCU, but I'm just thinking that I'd be best off with an ignition system that isn't designed for inputs that no longer exist. Yes?

[Lincolnmania]

80's 351 4bbl trucks and vans had eec4......at least the few i worked on

[Mercracer]

To kind of go against the crowd here, I wanna say that the newer Duraspark will be fine without all the other inputs. Of course, I don't have any evidence yet to prove that.

Sometimes, it is better just not to post random thoughts.......

[Nathan in MI]

I'm wondering if it might be a good idea to archive this thread. After all, most of the guys that convert to carb from CFI/EFI use Duraspark setups, and it'd be good to have this information there so that in the future, people know that there are two different systems from which to choose, and which one they SHOULD choose. Yes/no?

[gadget73]

The 87 F250 351w I had at the marina did not have EEC IV. Dspark igntion, no idle stepper, etc. The 84 F250 with the I6 that Scott had at the shop last year had a TFI module, an idle stepper, a 1bbl carb, and an oxy sensor. You figure it out lol.

[Mercracer]

I'm wondering if it might be a good idea to archive this thread. After all, most of the guys that convert to carb from CFI/EFI use Duraspark setups, and it'd be good to have this information there so that in the future, people know that there are two different systems from which to choose, and which one they SHOULD choose. Yes/no?

Not much solid tech here. I will dig out my Duraspark II pictures and diagrams and put something in the archive..

[Forcus]

Since you were asking for opinions on whether to go with a newer carb but keep the Duraspark III (new style), my vote is that if you are comfortable with reconfiguring to a non-stock application and can troubleshoot, pull out the Duraspark III, replace with the II (old style), replace the distributor with an aftermarket vacuum advance, and replace the carb with a good 4 bbl with vacuum secondaries.

I went through this with my 1990 RX7 Turbo II. It had an incredible amount of vacuum lines which had a tendency to get brittle with the extreme heat and could lead to blown engines. I took a scan of the factory harness and removed and rerouted everything in photoshop. Then went to the engines, removed all of the wires from the harness that were unneeded and modified the vacuum lines and routing, replacing with new.

Started first try even though the car was disassembled when I got it and had not ran since the mid 90's (engine caught fire). My opinion is that the Duraspark III and computer controlled carb (maybe it should be computer influenced..) were probably acceptable back in the day but being 25 years old, reliability will suffer. Grab a new distributor and a newish carb, set the carb, set the timing, and away you go.

[GoodSamaritan]

Let me hijack your thread for just a moment.

[hijack] I don't want to get this thread off topic, but I just made a post that might be relevant. There is a cheap option that doesn't involve any of the stock ford stuff.

http://www.grandmarq.net/vb/showthread.php?t=18817

[/hijack]

[Nathan in MI]

Since you were asking for opinions on whether to go with a newer carb but keep the Duraspark III (new style), my vote is that if you are comfortable with reconfiguring to a non-stock application and can troubleshoot, pull out the Duraspark III, replace with the II (old style), replace the distributor with an aftermarket vacuum advance, and replace the carb with a good 4 bbl with vacuum secondaries.

Started first try even though the car was disassembled when I got it and had not ran since the mid 90's (engine caught fire). My opinion is that the Duraspark III and computer controlled carb (maybe it should be computer influenced..) were probably acceptable back in the day but being 25 years old, reliability will suffer. Grab a new distributor and a newish carb, set the carb, set the timing, and away you go.

Why would I need to use an aftermarket distributor with a Duraspark box?

[1987cp]

Let me hijack your thread for just a moment.

[hijack] I don't want to get this thread off topic, but I just made a post that might be relevant. There is a cheap option that doesn't involve any of the stock ford stuff.

http://www.grandmarq.net/vb/showthread.php?t=18817

[/hijack]

The linked-to page, gofastforless.com, doesn't seem to link to any descriptive pages .... do you just hook that Chrysler module to a Duraspark distributor like with my HEI setup?

[1987cp]

Why would I need to use an aftermarket distributor with a Duraspark box?

Because you can't spend $250-$500 buying a stock-replacement Duraspark dizzy at AutoZone! :p

[Mercracer]

Since you were asking for opinions on whether to go with a newer carb but keep the Duraspark III (new style), my vote is that if you are comfortable with reconfiguring to a non-stock application and can troubleshoot, pull out the Duraspark III, replace with the II (old style), replace the distributor with an aftermarket vacuum advance, and replace the carb with a good 4 bbl with vacuum secondaries..

It would be silly to use a Duraspark II module with an aftermarket distributor. We are drifting off into the realm of bad tech again. You can just get an aftermarket distributor that is self contained other than a HEI. If you want to get creative but have more spark and a multiple spark ignition, you can use a MSD box with a Duraspark II distributor or even a points distributor because the distributor becomes just a trigger and mechanical advance mechanism. Points last forever because there is very low voltage going across them.

[GoodSamaritan]

The linked-to page, gofastforless.com, doesn't seem to link to any descriptive pages .... do you just hook that Chrysler module to a Duraspark distributor like with my HEI setup?

Exactly.