Rebuilt distributor

GPA · Post by **GPA** » Tue Feb 16, 2010 11:03 am

Hi,
I have a distributor, was sold as rebuilt, but looks like new, pictures in the Members Photo Gallery(Page 5 "GPA"). Looks like good quality, US coil etc. The tag on it says:

IGNITOR 24V.D.C.
ORD.NO.7762684
MFG.NO. DSG-022762
SERIAL NO. 005
NAPCO INTERNATIONAL
HOPKINS, MN 55343
US

I would like to install it in my rebuilt M38A1 F-head. Anybody can tell me what it was made for?
Zoli

Post by **wesk** » Tue Feb 16, 2010 4:13 pm

That's a replacement distributor manufactured by NAPCO Intnl.
http://www.napcointl.com/en/home/product_divisions.html
It is the equivalent to the Auto-Lite IAU4004UT ORD# 7375375, FSN 2920-776-2684 which was the early M38 distributor.

GPA · Post by **GPA** » Tue Feb 16, 2010 4:57 pm

Thank you Wes,
Do you know if the advance curve is different to the M38A1? I have some military manuals, but I have never seen ign. degrees@rpm values or a plotted graph, only basic timing. Do they exist?
Regards,
Zoli

Post by **wesk** » Tue Feb 16, 2010 9:39 pm

IAU4004UT (Early M38)
Max Governed Advance = 11 Use advance curve C2-P22

IAU4006UT (Late M38, and can be installed on M38A1/M170)
Max Governed Advance = 11 Use advance curve C2-P22

IAU4006AUT (M38A1/M170)
Max Governed Advance = 11 Use advance curve 1046

Advance curve RPMs are distributor RPM

Advance Curve 1046
300 = 0, 425 = 1, 1050 = 6, 1575 = 10, 1700 = 11

Advance Curve C2-P22
275 = 0, 385 = 1, 925 = 6, 1365 = 10, 1470 = 11

GPA · Post by **GPA** » Wed Feb 17, 2010 2:29 am

Thank you Wes,
In your first reply you have said it is a late M38 dist (IAU4004UT) I like that. On the second it is early which is not the best news. If it is early it was not recommended for M38A1/M170 use whit its faster advance rate? I can recurve it, if necessary or try to trade it with somebody. What would you do?
Zoli

Cacti_Ken · Post by **Cacti_Ken** » Wed Feb 17, 2010 1:28 pm

Wow, I didn't realize there were different advance curves in the 24volt distributor.

And then I don't know a darn thing about advance curves. As far as I think, my jeep runs ok. It has a IAU4006UT. Which is not what it had when I bought it.

It came with to me with a civilian distributor. And I just picked up a 24volt distributor off ebay not knowing there were different models.

Post by **wesk** » Wed Feb 17, 2010 6:20 pm

The NAPCO ORD # is consistant with the early IAU4004UT distributor but I suspect it is actially closer in appearance to the later IAU4006UT distributor.
I corrected the typo in my first post.

Ken,
It makes sense for the L134 and F134's which are significantly different engines to have different advance curves. Although the M38A1 distributor was engineered specifically to compliment the manifold/induction characteristics of the F134 it can still be used in the L134.

The main difference between the IAU4004UT and the IAU4006UT is the first does not have the noise filter (capacitor) built in. They both use the same advance curve. The IAU4006AUT differs from the second distributor with better water proofing and the F134 advance curve.

GPA · Post by **GPA** » Wed Feb 17, 2010 11:50 pm

I will test and modify the distributor advance mechanism, if needed. May need only the springs from my old distributor. Thank you Wes.
Zoli