After reading posts, and the nature of my build, I am wanting to get a stock distributor for my 400.

Previous posts have recommended sticking to Motorcraft Duraspark l, favored I believe, over the Duraspark ll. Also it was recommended not to go with the aftermarket as these are of inferiour quality compared to Motorcraft.

My problem is that Ford wants about the same or my for the stock part than the type of motor I'm trying to rebuild. A check of Napa, Autozone, and I think Advance don't carry Motorcraft, one store states that Motorcraft parts are now exclusive domain of Ford dealerships.

Also, I think it's been stated that I have to make modifications to the advance mechanism of the Duraspark l to enhance its performance. Is this required and why?

Where do i get what I need and how hard are the modifications? Where are the instructions for the modifications ? Thanks, I'll be looking for the responses. I'd like to pick up the distributor very soon if possible.

 

NAPA Reman. (Electronic w/o Module)
482893 $ 52.49
Core 22.00
w/o Governor, w/ Single Vacuum Advance

482873 $ 52.49
Core 44.00
w/o Governor, w/ Dual Vacuum Advance

Forgot what single versus dual was but I think I need the single. I am running a F-250 400/c-6.

 

There are a lot of after market products out there that are equal to or better than Motorcraft. ( did I say that?) Then there are those other brands. Most napa brand parts seem to be ok, but remember napa only makes boxes not parts.
You might quiz your dealer on who builds their distributors and it's components.
The modifications your talking about I assume is setting up your advance curve.
By this I mean the centrifugal advance this is best done on a machine.
But it can done on the engine. By changing springs on the advance weights you can control the curve. It would be quite long winded to explan the full process here. Doing this right is well worth the trouble. So many folks go to all kinds of elabrate lengths when assembling an engine an when it comes to this, They either ignore it or half... it. That is shame as most will never know the true potential of their creation. If you can find a copy of Hot Rod's High Performance Series Volume 4 Number 1 , There is 4 chapters on distributors and timing and Cam indexing that are awsome. I reccomend you have this done on a machine by a competant tech. But if you wish to try it yourself I'll see if I can maybe get some articals to you that will help.

Pat

 

The Motorcraft DS modules are the best and over the RPM range for a 400 they will outperform the aftermarket "racing" units. I would go with the DS-II unit tho.

The modifications to the stock distributor are to eliminate EGR ping and involve the vacuum advance mechanism.

Getting the distributor tuned on a dyno by a competent tech is your best bet.

I have listed the distributor specs for a 1971 400 in a thread in this forum.

 

I have a fairly clean original Motorcraft distributor. I don't see anything obviously wrong with it but I'm no expert and don't know what to look for exactly. The pinion? gear has a few shiny areas but the teeth/vanes appear to have no rounded out, chipped, or otherwise messed up areas that I can tell. The shaft needs cleaning up.

I just thought it would be best to use new parts for certain key components.
Based on your postings that the original is a good part, I probably will use it. I could use it as a core (that's $30).

Why would one person prefer the Duraspark ll over the Duraspark l and vice versa? Is the difference EGR vs Non-EGR? My Edelbrock intake is the 2171, non-egr.

How do I tell if it's the dual advance vs. single advance ... Duraspark l or ll?

Dyno testing... this is silly but it's really a tuning process? For now, how much would I expect to spend for this?

 

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:
https://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 in some driving modes.

As far as the cost for a dyno tune it will depend on the shop. Check around but the cheapest shop may not be the best.

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.

Engine specs for the 1971 400:
260HP @ 4400 RPM, 400 LB-FT @ 2200 RPM (Brake/flywheel figures)
Compression: 9.0:1
Carb: 2V
Engine code: S
Available in: Custom & C-500, LTD, Galaxie 500, Monterey

 

Thanks for responding and I appreciate the links to BB's diagrams. Good information. I 'll go with the DS ll after cleaning it up some. I just don't want another parameter to troubleshoot.

I'll do some research on distributor inspection looking here, Monroe's book, Chilton's and the shop manual .

 

I would make sure the distributor is functional with working advance mechanisms to start up your engine. Tune it up later. Or you could use another known good part. The fewer unknown components the better when first starting a new engine.

 

This distributor is unknown to me except it is cleaner than the original. Is there a bench method of knowing whether the advance mechanisms are functional?