Dramatically better MPG with the DurasparkII

[JackFish]

Just did this mod to my '72 Maverick (Duraspark II distributor from an '83 Mercury fired by a MSD 6AL box and MSD Blaster TFI coil).

Problem is (if it is a problem), the car will not run with the vaccum advance hooked up anymore. As soon as you try to rev it up with the vaccum advance connected, it coughs out the carb and dies. Without the advance connected, the car runs excellent. It accelerates WAY better then before and screeches the tires going into 2nd gear. I am getting way better gas mileage around town and on the highway. Between about 40 and 70 mph, it accelerates like never before. Since it runs so much better, should I just leave it as is with the vaccum advance disconnected?

The ds2 dizzy needs spark port vacuum from the carb. It should be connected to a port on the carb that is above the throttle plate.

 

[JackFish]

I am going to try this mod, but I waant to be sure I am replacing the correct spring with the mr. gasket spring. The way I understand it the spring I need to replace is the one made out of the thinner wire... and bend the tab in on the thick spring?

I disagree with that. It seemed to me upon close inspection that the "heavier" spring is the one with the thicker wire. And that is the one that I replaced with successful results.

I've said it before, and again, I believe the sticky has some confusing info that should be corrected.

 

[JackFish]

I did not bend any tabs and have had successful results changing the secondary spring out, which is the thicker, heavier spring.
This allows the advance to come in sooner (more quickly) and smoother.

 

[Patrick66]

I did not bend any tabs and have had successful results changing the secondary spring out, which is the thicker, heavier spring.
This allows the advance to come in sooner (more quickly) and smoother.

this one?

 

[JackFish]

IIRC, yes.

 

[xpsnake]

Was there ever bottom line clarification to this mod?

 

[60s Refugee]

So, I take a rebuilt 1978 DSII from Advance Autoparts and jamb it in the hole, hook up the modules and stuff, and use the factory vac advance using the stock Autolite 1100. I leave the DSII springs and tabs alone. What can I expect?

Harry

 

[frogmn666]

I want to know this too. That's what I'm in the process of doing. I've curved dizzys before, but there are so many variables, compression, total advance, when it comes in, load, gearing, air temperature, altitude, etc.

If nobody objects to a DSII thread that has already been beat to pulp, I may do one on using a late `70 series Fairmont dizzy with a parts list, pics, and results. I've already seen many descrepencies with this install and there are some critical items and precautions to note.

I am by no way an expert on timing, but I have been working on engines since I could hold a wrench; over 50 years experience and may be able to clear up a few things.

Below is a link to a long and good read that I've read through and totally agree with. Don't let this thread die or get locked as there are new people like myself that need to know the right way to do this. I will add what I can as I progress.

Any of you experts know if there is a difference between 10-13L and 10-15R slots? My 78 DSII has 10R and 15R curves.

http://www.carbdford.com/viewtopic.php?t=5543

 

[grocery getter]

I used both springs in the 925d kit. I didn't like the ease of advance, so I bent the tabs out.

before this I had a miss at cruise.
now, it's smooth through the power band.

yeah, it's a bit of a monkey wrench in this thread.

bottom line... too many variables in a 40 year old car. you need to play with it. 8)

Mine--->12 degrees static on the 13L arm.
aussie head, 2v carb using port vacuum.

 

[BIGREDRASA]

I just did new topic, taking off from this one, with emphasis on economy instead of power.

 

[BIGREDRASA]

Here we go again. Took out the dizzy, and found I have the 13R and 18R slots. It is currently set on the 18R. I'm running 12* initial. I had a light spring in my goodies box, but it feels as heavy or more as the one in the dizzy.

At 80 MPH or around 3100 RPM, I have to really stomp on the gas to go up our gentle hills (Platte River Road/ I-80 have no more than 6* grades). I bent the arm on the heavier spring, but left everything else as is, for now.

Million $ Question: Stock cam, head and .040 pistons. What is a good ballpark for total advance? I'm going to see if Offutt AFB Hobby Shop has a Sun Machine.

By the way, the unofficial speed limit on I-80 across Nebraska is 80 MPH.

 

[frogmn666]

Try this link: http://www.carbdford.com/viewtopic.php?t=5543

 

[BIGREDRASA]

Try this link: http://www.carbdford.com/viewtopic.php?t=5543

Thanks, been there. Maybe we can explore setting up a "How To" section? Not just Stickies?

Another member is trying to resurrect & recompile the info, specifically for our 6s.

 

[frogmn666]

I'm still waiting for the weather to cool off before proceeding with my Duraspark II mod. I had a 20% off coupon for Autozone and went ahead and bought the actual Duraspark II module since I didn't have good luck with the GE module.

Right now, I have the stock set-up in my 66 Stang. Runs good even with indicated 18° initial advance. Pretty sure my TDC is correct, but I'm going to re-check it with a positive piston stop.

 

[Ronbo]

Ok...Police Interceptor...for the 200 six? Confused here. I DID play around with the springs in my old distributor a bit but after a bit of admonishing went back to the original set up. So what gives? Modifying the advance can reap benefits but...there are many factors to consider? I made huge gains with my 300 messing around with the curve (got lucky) but when I went from AZ to GA had to change things around some to get the same gains (springs/jetting). Anyone?

Ron

 

[351 celi]

http://www.gofastforless.com/ignition/advance.htm

Hey guys. The above link really helps me understand the effects and function of each spring. Hope this helps some others modify their advance curves. I already have the 925D spring kit, but was unsure of the installation as people have had such varying results.

 

[60s Refugee]

I removed the so called "pursuit" advance springs because they didn't help, and caused tuning issues. I removed the springs, put the originals in, and everything works now!

Harry

 

[351 celi]

I installed the both springs in the 925D kit last night, all went smoothly. I set initial at stock 12 degrees, and all in occurs at 2600 RPM. Theoretically, I should be getting 38 degreest total mechanical advance with the 13L slot utilized. I made a timing template today in AutoCAD that I will mount on my balancer to verify this, and then try to increase the initial some more. So far, I am pleased, it is more responsive than oem. I only had to bend the stationary tab on the light spring slightly to make sure I had enough tension. I realize this thread is supposed to be focused on economy, but I thought another result of the installation of this kit may be helpful to others...

 

[JackFish]

I only had to bend the stationary tab on the light spring slightly to make sure I had enough tension.

Do you mean the primary or secondary post?
It appears to me that both of the springs in the kit are the same, i.e. "light".
I only replaced the secondary spring, did not bend any tabs, and I can say the result was a very smooth accelerating and peppy motor, but I have no empirical facts to offer at this point.
I think leaving the primary "stock" as per my application results in a very smooth off-idle response, combined with a more "free" midrange to WOT.
If I hammered it from a stop it revved up to 5000rpm in first.

 

[BIGREDRASA]

If you saw my post http://fordsix.com/forum/viewtopic.php?f=1&t=53109 , you'd see that I found no measurable difference between the "Light" spring and the "925" spring.