Dist Rebuild--IAD 4008--perf specs

[omtay77]

Quick question for the gentlemen of the 'G'...

I've found a place here in Seattle to test/verify a recently rebuilt (by me) Autolite IAD 4008 distributor. The shop has asked for any and all performance specs so they know exactly what to test for.

Question...can I just hand them the pertinent section(s) of TM9-1825B?...or is there something additional I need to communicate to them before they get started?

Thanks in advance,

tom b.

[Marty, SoCal]

See if they can add in a bit more than stock timing advance,the Jeep will preform better on modern fuel. Not sure buut there probably is a utolite Distributor TM somewhere with the original specs. Might be in one of the CJ manuals, too.

Here's a pretty good thread from the CJ2A forum:
http://www.thecj2apage.com/forums/impro ... 23412.html

[Joe Gopan]

TM9-1825B Auto-Lite Electrical Equipment.

[omtay77]

Got it...

TM 9-1825B
T0 19-75CB-3
(Autolite)

Thanks Ben!

tom b.

[omtay77]

See if they can add in a bit more than stock timing advance,the Jeep will preform better on modern fuel. Not sure buut there probably is a utolite Distributor TM somewhere with the original specs. Might be in one of the CJ manuals, too.

Here's a pretty good thread from the CJ2A forum:
http://www.thecj2apage.com/forums/impro ... 23412.html

...and thanks Marty...I'll include this when I take the disty over this afternoon...

thanks guys!

tom b.

[artificer]

[Joe Gopan]

The IAD 4008 is not shown on the above chart and will have different specs than those listed.

[artificer]

The IAD 4008 is not shown on the above chart and will have different specs than those listed....from an earlier thread on this same topic....The Ordnance TM for the Autolite Distributors has no tension data on the governor springs, nor weight values for the governors. Instructions are just to discard if bent or Distorted. Governor Weights and the shaft are to be inspected for wear and replaced if governor pivot holes are loose fit and also the shafts if they are a loose fit at the governor weight locations. Other than that, there is nothing much that can be done with the governor weights and springs.

That is most helpful....so what are the specs, Joel?
If one can't find them in the appropriate TM or if it is not in the TM, are you saying it can't be done?

Maybe this will help the OP out & he shouldn't forget Marty's LINK & advice about getting a bit more pep.

IAD-4008 [spec's relate to machine which runs @ 1/2 crank speed for calibration]:
250 RPM - 0º advance
350 RPM - 1º advance
1400 RPM -10º advance
1500 RPM - 11º advance

Bend or Not to Bend?
Of course you need to bend the tabs, that’s the only way to get the proper tension on the weights for a workable timing curve.

If you do not have access to a distributor test machine and you are replacing the weight springs, the best you can do is adjust the spring tabs so that there is no free play in the springs. You do not want the spring loose between the tabs and weights.

The timing curve for the IGC 4705 and IAD 4008 are not the same, but both distributors are for the same engine. The timing curve difference between the two is nothing more than a tweak of the spring tabs, even thou they are different spring sets.
The only workable difference in the shaft assemblies for the two distributors is the cam points plate. The IAD 4008 has a taller one and the IGC 4705 is shorter.

Both distributors do have an anti-rattle spring that is connected to the bottom side of the cam point’s plate. None of the technical diagrams that I have for the IAD 4008 show that Spring.
The technical manuals are great for working on Jeeps, trucks, & tractors, but as I have learned, the technical manuals are nothing more than a framework or guideline of direction to work from.
Kurt Hostetter, Willys Distributors

[omtay77]

Just heard from the shop that ran my disty--short version is, they recommend a 32 degree advance. This seems a bit much, even after reading the thread on the CJ2A forum that Marty linked me to.

I'll find out more after I get over this afternoon to pick it up.

tom b.

[Marty, SoCal]

32* total at the flywheel is probably what he is recommending. This figure would include the initial timing advance.

5* before is stock timing. 11* at the distributor is 22* at the crank. This would net 27* total at the flywheel stock. Adding in either 5 more degrees initial or 5 more into the mechanical advance (Flywheel degrees) would net 32* total. The jeep would probably run well with 10* initial, but it may cause the engine to crank over too slow. If he could add in 2.5* more of distributor mechanical advance, that would net you the 32* goal, but allow you to keep the stock initial timing. It should run really well on modern regular fuel. After that's done, you could play with the initial timing a little bit, seeing how adding more initial would effect cranking speeds or if it caused any pinging. A good rule of thumb is to advance the timing until pinging is heard upon moderate acceleration, then backing the initial timing off 2-3 degrees.

If it all works out, please update the post after you have driven your jeep.

See if the shop owner would let you post their info. Also, if he is willing, let us know what he would charge for recurving someones distributor. Some people don't have access to a local shop with a distributor machine or a good tech to recurve their distributors for them.

[Chuck Lutz]

Note that Kurt has reminded everyone that the shafts are different....we already know the weights are different....and Kurt pointed out what we also knew about the springs, that the SPRINGS are a different tension so be careful in trying to assemble either the 4075 or the 4008 with parts from the WRONG rebuild kit!

[omtay77]

Marty...thanks--that's reassuring. It will be a couple/three months before it's running, but I'll update this thread when it is. I'll also ask about posting his results and a charge for recurving a shipped-in disty. I'm hip to the challenge--I had to call all over town to find someone that can still do this. For locals here in Western WA, it's Autosport Seattle, in beautiful downtown Ballard. It's the kind of shop overflowing with motors from vintage autos in various states of rebuild, Jag XKE up on the lift, and so much STUFF in general, it's hard to move around.

Chuck...I didn't replace weights,shaft or bushings, just the springs ( bought from Ron). I was lucky in that the disty I was working on had no play in it that I could discern. I just disassembled what I could, cleaned it up, repainted it, replaced the springs, checked the pull per TM9-1825B (and anything else I could glean from here on the 'G'), set the dust cover, a couple drops of oil on the felt, installed fresh condenser and points, and called it good.

Fingers crossed

tom b.

[sutts]

Note that Kurt has reminded everyone that the shafts are different....we already know the weights are different....and Kurt pointed out what we also knew about the springs, that the SPRINGS are a different tension so be careful in trying to assemble either the 4075 or the 4008 with parts from the WRONG rebuild kit!

The shafts are different Chuck but Kurt has assured me that the 4008 shaft will work just fine in the 4075.

"The part number is not important, what is, is it will work just fine in either a IGC 4705 or IAD 4008 distributor without any modification."

Dave