[Schurkey]

Originally Posted by Half-Inch Stud

990 module is to generic, so I recall GM & yellow vs white dot were sorted vs replcement modules.

Has anyone else seen GM modules with white vs. yellow paint dots on them?

GM doesn't have different part numbers for "white dot" vs. "yellow dot" modules. The modules are the same regardless of the colored dot painted on 'em.

I have to suspect this is some assembly-line ID, where modules (and pickup coils) are sorted for eventual use with red-and white, or red-and-yellow ignition coils.

Pickup coils are intended to be a matched set with the ignition coil--but the modules are the same either way.

The four-pin HEI is based on a Motorola IC, MC3334P., with a bunch of other capacitors, resistors, etc. supporting the on-chip functions. I suppose we could buy some Motorola chips, and MAKE OUR OWN MODULES. (No thanks, I have enough projects...)

https://www.futurlec.com/Motorola/MC3334P.shtml

[Sun Tuned]

Well the purpose of my little testing was to demonstrate how the modules kinda work.

I knew going in that the better quality modules, will actually switch reliably over 10,000 rpm. Since my machine is set up to turn roughly a hair more than that I pretty much use 10,000 rpm as my stepping off point. I also knew there are only a very few coils that will go near this far.

There is some definitive power to be had by getting it right in the above 6500 rpm ranges also. That is if you need power above the 6500 range in the first place.

I know the coil I'm using is good to 10,000 rpm without question. So the question becomes all else equal what happens if we start swapping in n out modules of different brands and makes?

That's where we are at. I know I'm not smart enough to go trying to build modules for my HEI and I'd bet a dollar not many here would try either even though that may be what their field of expertise is. The avg enthusiast will just swap them in and out. Quick easy and very fast this way.

I certainly know if I see a problem I'm not going to be able to correct it unless I switch it out. Just not gonna happen.

[Shiny]

Great learning on this thread. Thanks all for sharing.

I expect another indicator of "design and mfg quality" will be repeatability from module to module. So far, all the modules seem to be OK up to maybe 5000 rpm but if variation from unit to unit was high, the 5K module could be the lucky one and others might fade away below that.

[Sun Tuned]

That's another viable concern. When I test these things or as I do it I'll be testing two of each to see that a check is kept on that. The money can quickly get out of hand on this trying to do 3 and 4 of each and realistically I don't see the need. 2 each should be fine.

Just keep everything the same and just change the module.

Mick no shame in not testing em over 5000 rpm. Unless you set down and hand modify an old distributor machine to be a turntable mule, the only other option is do it in a live engine... that don't work real well. Dangerous enough doing it on an old purpose built machine. Make no mistake these things are really moving at 8,9,10,000 rpm.

The machine makes it much easier and lots safer. At this level and type of testing anyhow.

We will get to some good stuff here shortly I promise.
Just keep the Delco module info at hand nearby and we will take a tour of what's going on.

[firechicken]

Really interesting stuff here.
I use a MSD module in my HEI only for the built in rev limiter feature. It seems to work fine on my engine to 6500 rpm but curious if any testing has ever been done with these?

[68 Firebird]

Interested to see if you could test the DUI Dyna Module as well. Been running A DUI HEI for years and have no complaints. Gerry

[Sun Tuned]

Sure I will Gerry.

Their coil that's in there now.

Use their stuff here quite readily. You might say I know em pretty well.

[Sun Tuned]

The MSD module works well. I have not checked the Dwell numbers on one though. Installed about 6-7 for customers that sent em in. Attgis time all I know about them is when used with their coil they will fire every bit up to 7500 without any fade.

Don't currently have one to test though.

[Sun Tuned]

Here's a Wells brand module from last year....

RPM Dwell
1000. 14
2000. 25
3000. 30
4000. 35.5
5000. 36.25
6000. 35
7000. 33
8000. 32
9000. 31
10,000. 31

There we have a few extra degrees here and there.

If you are looking for a module with more Dwell in it than the run of the mill stock module this is the direction you want to go in. Make the whole engine run just a little sharper and crisper than the stock module. In real world hp increases here we are only talking about numbers less than 5 hp tops. So we aren't moving the earth or anything extravagant just by changing the module. Still though 5 hp is a lot when your looking for 2 here and 2 there. A comparison of the Dwell readings will allow you to see where expected gains will be found but suffice it to say about all you will notice is a little crisper idle and on average about a 2-5 hp increase over about a 2000 rpm span.

On the other hand if the module and coil aren't compatible and the deal runs into misfire then you stand to lose large amounts. For what is done with buicks, olds, Pontiacs ... 7500 rpm is out of the ordinary anyhow. But a little searching for the right module just might pay some dividends.

["QUICK-SILVER"]

Originally Posted by Schurkey

Has anyone else seen GM modules with white vs. yellow paint dots on them?

Got two NOS white dots this past week. Sun Tuned's other thread started me beating the bushes for them.

Different date codes on them and they do not work the same. Only one is a Singapore. Slow turning and flipping the distributor gear fast with your fingers....The Singapore makes a lot stronger coil spark than the other. Didn't have anything set up to check current or dwell time. Just letting the spark jump a wide gap.



Clay

[Sun Tuned]

I haven't gotten into the beryllium oxide vs aluminum oxide heat sink thing inside them, and may or may not. But also consider if you're sourcing used ones that one vs the other may have or may not have been working harder for longer than the other.???

I've seen modules with yellow and white or even blue dots on them from the factory. Never paid much attention to them
Other than that may have been some organizational thing. D1906 is D1906 no difference.

I haven't had any issue with the Singapore made modules outside normal attrition due generally to ignorance.

[Ben M.]

Originally Posted by "QUICK-SILVER"

Got two NOS white dots this past week.

I've got a NOS still in the plastic and box from Singapore around 1983 that looks just like the upper one in your photo (990 0E18 inked on it).

I have another module that just says "Made in USA" and nothing else, I presume this to be some aftermarket company's knock off.

[Sun Tuned]

You get out there trying to find one and it seems everyone you look at the sales pitch is "ours is better than theirs"

Ok fine, but why? That's when the crickets start or you get a barrage of technical stuff that makes little sense.

I'll do some testing and find the top three that are out there and report back what I find. Already done some testing on the ones I recently had trouble with in the other Module quality thread, and absolutely did not like what I saw. Got some hard numbers on those.

Let me summarize the GM module deal.
74- early 76 we saw the solid white module
76-84ish we saw the black GM module like in pics above.
1984 ish to 2008 we had the same black GM module stamped "Singapore" on back aluminum plate in blue ink.
Now here is where the problems started... somewhere in around 2009 or so apparently GM decided to subcontract these with Wells. Then you started seeing the exact same Wells module Autozone sold but in a GM box,and at roughly twice the jobber price they were. They went from
32.00 to 59.00. Operation was fine at the time,just the price was high. Then about 6-8 months later the same Wells module has now been modified for GM to have a reworked "GM" raised script on the top module cover. This looked markedly different than the old raised GM script. Price still fairly high at 48-49 dollars jobber. Have not sourced these from Delco in last 6 months. Newest Standard ignition, Wells, and Napa modules are said to be from same manufacturer. That said my concern is the Delco version is also from same source and if so I have real reservations about performance of these in almost any application.