Duraspark Distributor

[crawlfish]

After rereading earlier posts, the Duraspark ll seems to be recommended for this low rpm 400. The parts store has a remanufactured Motorcraft below $50.

Q1: How to tell whether its a Duraspark l or ll?
Q2: My application is non-EGR so do I need single or dual vacuum?
Q3: What else must I have? A recurve/advance kit? If so where do I get it?


'79 F-250, Camper Special
400, Flat tops, Comp Cam 255DEH
Edelbrock 600 CFM, and Intake

[PROSTOCK]

If you spec'd the '79 for the year model, it almost has to be a II. I have a nearly identical setup('78 Bronco) and use a single advance. I have not re-curved it though.

[crawlfish]

Thanks ProStock. I spec'd it for the '79, and anything '77 above was DS2. DS2 is pointless and DS1 is points? Anyway, this is useable for me out of box right?

I see alot of information on DS2 modifications and upgrades using spark advance curve kit, TFI/HEI modules etc.

I haven't a clue why this would be important to me. I understand the stock is fine even with nitrous +150 more HP. Why would I want to spend time learning how to do the upgrade or spending the money?. I'm not ever going to see rpms over 5500 and bet I'll be way below that. Just want to understand why so many are pushing it.

[Torque1st]

The stock advance mechanism is set up for use with EGR. This will cause it to ping under light load or cruise mode. The vacuum advance must be set properly to eliminate the pinging. Use the following advance specifications. You may need to find someone with a distributor machine to set it properly.


1971 distributor & engine specifications for the 400
================================================== ==
This was the GOOD year for the 400 engine before it was smogged to death.
-------------------------------
Distributor part #D00F-U
Centrifugal Advance Start: 0-0.5° @ 350RPM Finish: 14° @ 2275RPM
Vacuum Advance Start: 0-1° @ 5" Finish: 12.5° @ 25"
Point Dwell: 26-31°
Initial Timing: 10° BTDC, 6°BTDC California.
Vacuum given in inches of Mercury (Hg).
RPM specified as distributor RPM.
Degrees specified as distributor degrees.
---------------------------------
Double those values for crankshaft figures:
Example: 0-0.5° @ 350RPM distributor becomes 0-1° @ 700RPM on the engine.
--------------------------------

[crawlfish]

Thanks Torque1st.

I believe somewhere in my project scrapbook I have information on how to do this. Seems I remember it has capability of two settings and I move the plate to another position? I'll look at my material but I need to know do I need additional parts?

[Bill_Beyer]

Point dwell??? On a DuraSpark?

Spend some time over on the Reincarnation Automotive site. They describe exactly how to recurve a DuraSpark distributor and even specify a model to start with, I believe it's from a 1975 Ford Elite. I realize it's a 385 series site but the distributor is the same for both engines anyway.

Duraspark recurve instructions

[crawlfish]

I asked about "single or dual vacuum" and I believe I should have asked "single or dual diaphragm". What's the difference?

I got the single diaphragm DS2.

I'm reading the articles now maybe I'll find out what a dual vs. single diaphragm vacuum is about.

[crawlfish]

Originally Posted by Torque1st

There are several different versions of the Duraspark system. The DS-II system is the most widely used and readily available. I could use any aftermarket ignition system on my truck and after researching and some personal experience I will be using the Motorcraft DS-II. You can find information on the DS wiring and systems here:
User BB's Duraspark diagrams:

http://www.ford-trucks.com/forums/member.php?u=1811

DS I and II don't have anything to do with single or dual advance. The dual diaphragm units were used to reduce emissions...

I went to the link again and for year 1979 this is the description:

Description: 1977-1979 Duraspark I. This system provides much higher secondary voltage to the plugs. A special coil is used in which the internal windings have a much lower resistance.

I'm confused. Note it states Duraspark 1 (one) not 2 (two).

Originally Posted by PROSTOCK

If you spec'd the '79 for the year model, it almost has to be a II. I have a nearly identical setup('78 Bronco) and use a single advance. I have not re-curved it though.

Do I have to spec it for a different year? If yes, what year???

I'll get the recurve kit later on I just want to install this thing in my truck in time to get this year's firewood.

[Bill_Beyer]

I believe the only visible difference between the DS1 and DS2 is the DS2 has the larger cap. The DS2 came out in 1976 and was in production until 1981 when Ford went to the EEC system with TFI module.

[crawlfish]

Thanks for the reply.

The catalog showed pics with two lengths for that year and literature states to compare it with the core.

Problem is my core came from a different year. So without having a known DS2 I can't tell what I was given, except by the fact that I asked for a '79 distributor?

They didn't also make a DS1 in 1979 did they? Can I be sure I got a DS2 and that BB's diagram description for a 1979 is incorrect??


I need to have more to go on or just say wtf and let it go.

[crawlfish]

After going to the Cardone website and looking up distributors using different year specs, and getting the same part no. i a saying wtf and installing it.

thanks all for the input. i must have a ds2 but if anyone asked me how i knew i couldn't tell 'em.