Are all the 8 pin ignition modules that same?

[rang-a-stang]

I’m going to head to the wrecking yard here in a few days and need a new 8 pin ignition module. Are all the V8 and V6 8 pin modules the same? I prefer an OEM part over an aftermarket so I plan to look for a dirty original over a shiny aftermarket part. Want to know if I can check vans, S10s, Silverado, etc....

[In-Tech]

What are you considering to be an 8 pin module? The one with the 4 pin and 2 pin weather resistant connector that has 2 more pins that go to the reluctor? If so, they are all the same. Make sure to put heat sink compound and not dielectric grease under the module. You can use dielectric grease on all the electrical connections. I'm with you on the aftermarket being poor on all HEI modules. When I buy new I only buy Delphi these days, not even AC-Delco.

[rang-a-stang]

Exactly! (4 and 2 pin weather packs)
Yep, I have an obnoxiously big/ugly heat sync on it and heat sync compound.

thank you for the quick response, Carl!

[In-Tech]

NP, glad to help. :happy:

[tayto]

Another test: while checking the timing as the RPM was increased, both the 048 & 369 modules held steady until a particular RPM. This was with 048 & table 1, then 369 with table 2.

The 048 module, it held steady timing until about 3800 RPM where it retarded 4 degrees. Then by 5000 RPM the retard had increased to 6 degrees.

The 369 module, it held steady timing until about 3200 where it gained 2 degrees of advance. This held steady to 5000 RPM, which is the highest RPM it was checked at.

https://www.thirdgen.org/forums/diy-prom/497468-048-369-ign-modules.html

[In-Tech]

That's good info. I never saw a difference on any of the GM modules/distributors but the msd distributors definitely required a latency change in the MEFI computers back when I was checking all of this. Now it sounds like the MSD had an 048 module in it, I always blamed it on the ford style reluctor in the msd distributors . FAST355 is here and can probably shed more light on this. I'm glad you brought this to our attention. I guess I didn't have enough distributors laying around when I was testing stuff.

Next time I am at the junkyard I am going to grab a few modules and test in my distributor machine.

[delcowizzid]

Test them with an ecu running on them from what I remember they have the retard built in for limp home mode running and ahouldnt have the timing shift if the are in est mode being controlled by the ecu

[Fast355]

Test them with an ecu running on them from what I remember they have the retard built in for limp home mode running and ahouldnt have the timing shift if the are in est mode being controlled by the ecu

They actually have advance built into them in limp home mode. Alot of GM based carbureted marine engines use the TBI distributor and module in bypass mode. Alot of GM based carbureted marine engines use the TBI distributor and module in bypass mode. The marine modules are specific but even a TBI truck module has 8* or so above 1,500-2,000 rpm.

The Davis Unified Ignition module is probably the best 8 pin EST module you can buy.

EDIT---Corrected myself after pulling up an older thread on this on TGO.

Attached is the advance curve of a dedicated marine module, which is a direct swap for the GM module. From memory they set the timing at 10-12* BTDC.

[rang-a-stang]

I'm still pretty new to this so a couple questions up front:
A) Are 048 and 369 both the same type of modules but different versions?
B) Seems like I should look for the 369 module. If so, How do I identify it and is it plug and play?

My configuration: AMC 401, fresh rebuild, Performer intake, Comp Cams 268H, 16197427, 454TB, $0E

My symptoms: timing is set to 0, with timing plug pulled timing stays steady at 0 and it idles well. I also get a CEL when setting the timing (I assume this is normal since my computer does not see the module, and once I plug the module in, reset the computer, the light goes away). I plug in timing signal, timing bounces between between 18 and 20 (both watching at the damper with a timing light and at TunerProRT) and it occasionally surges. Give it any throttle and it quickly goes to about 32 and backfires like mad. Symptoms are the same in open or closed loop.

Recently, I was running well but had low oil pressure. I rebuilt my oil pump (involves pulling the dizzy), now have awesome oil pressure but these symptoms. I have not verified my TDC marker since the oil pump rebuild and plan to do so soon but was also going to throw a module at it while I was in there.

Anything else I am missing/should consider?

[Fast355]

I'm still pretty new to this so a couple questions up front:
A) Are 048 and 369 both the same type of modules but different versions?
B) Seems like I should look for the 369 module. If so, How do I identify it and is it plug and play?

My configuration: AMC 401, fresh rebuild, Performer intake, Comp Cams 268H, 16197427, 454TB, $0E

My symptoms: timing is set to 0, with timing plug pulled timing stays steady at 0 and it idles well. I also get a CEL when setting the timing (I assume this is normal since my computer does not see the module, and once I plug the module in, reset the computer, the light goes away). I plug in timing signal, timing bounces between between 18 and 20 (both watching at the damper with a timing light and at TunerProRT) and it occasionally surges. Give it any throttle and it quickly goes to about 32 and backfires like mad. Symptoms are the same in open or closed loop.

Recently, I was running well but had low oil pressure. I rebuilt my oil pump (involves pulling the dizzy), now have awesome oil pressure but these symptoms. I have not verified my TDC marker since the oil pump rebuild and plan to do so soon but was also going to throw a module at it while I was in there.

Anything else I am missing/should consider?

When you are looking at an OEM junkyard module the 369 and 048 will clearly be stamped on top. Many fullsize G-vans got the 369 module in either a 4.3 or 350 V8. A lot of the TPI cars had the 369 as well but those are much less common then the vans in the wreckers.

As for your issue, for older slower burning heads it sounds like you may not have enough timing advance. Retarded ignition timing can cause the engine to backfire. What was it timed at prior to the distributor being removed? I have not messed with a 401, but I have a 304 and a 360. Both of them liked 12-16* of initial advance with 22* centrfical from the HEI and about 10-14* vacuum advance. At 3,000 rpm with the vacuum connected it is not uncommon to run 50-56* of timing. Not knowing what you have for a timing map its hard to say what your initial should be set at. If it is still a stock GM TBI timing table, I would bump your initial advance up to about 12* and test what happens. The AMC V8s usually make best power with 36-38* of timing advance and a stock TBI truck rarely has more than 22* at WOT. Also the timing maps on the GM TBIs have a very slow advance rate and often negative timing values at high kpa and low engine speed.

[In-Tech]

Test them with an ecu running on them from what I remember they have the retard built in for limp home mode running and ahouldnt have the timing shift if the are in est mode being controlled by the ecu
Based on what I read over at third gen it sounds as if they tested on a running engine. When I gather enough modules my plan is to spin it up on the distributor machine with a 7427 and harness I have laying around. Just for my own curiosity. I was always told when in limp mode they all had a 10 degree jump at 1600 rpm so I'll check that too while I'm testing.

The latency issue with the msd distributors was found on the dyno. I was back east tuning a few engines and one was a combination we had done about a dozen times and always made ~940-950 hp and all of a sudden this one wouldn't make 900hp. After verifying everything we could mechanically I noticed the msd distributor and he said he just started using these so we checked the timing and it wasn't following what was commanded. Poor guy, I had him out at the engine verifying timing all the way to 6000 rpm while I adjust the latency numbers. I felt for him while he had to check all that with the engine screaming and a blower belt right there too. :( He came back in from the cell shaking like a leaf. :innocent2:

Thanks, Fast355 for popping in with that info.

[Fast355]

Based on what I read over at third gen it sounds as if they tested on a running engine. When I gather enough modules my plan is to spin it up on the distributor machine with a 7427 and harness I have laying around. Just for my own curiosity. I was always told when in limp mode they all had a 10 degree jump at 1600 rpm so I'll check that too while I'm testing.

The latency issue with the msd distributors was found on the dyno. I was back east tuning a few engines and one was a combination we had done about a dozen times and always made ~940-950 hp and all of a sudden this one wouldn't make 900hp. After verifying everything we could mechanically I noticed the msd distributor and he said he just started using these so we checked the timing and it wasn't following what was commanded. Poor guy, I had him out at the engine verifying timing all the way to 6000 rpm while I adjust the latency numbers. I felt for him while he had to check all that with the engine screaming and a blower belt right there too. :( He came back in from the cell shaking like a leaf. :innocent2:

Thanks, Fast355 for popping in with that info.

I am not sure on the limp stuff for all the modules, never have tested a TBI one just going off what another found. I just know that the marine engines had a nice ramp when they advanced and assumed they were the same. It was not until I looked at an older thread and the module part numbers I realized the marine was different.

[In-Tech]

I'm still pretty new to this so a couple questions up front:
A) Are 048 and 369 both the same type of modules but different versions?
B) Seems like I should look for the 369 module. If so, How do I identify it and is it plug and play?

My configuration: AMC 401, fresh rebuild, Performer intake, Comp Cams 268H, 16197427, 454TB, $0E

My symptoms: timing is set to 0, with timing plug pulled timing stays steady at 0 and it idles well. I also get a CEL when setting the timing (I assume this is normal since my computer does not see the module, and once I plug the module in, reset the computer, the light goes away). I plug in timing signal, timing bounces between between 18 and 20 (both watching at the damper with a timing light and at TunerProRT) and it occasionally surges. Give it any throttle and it quickly goes to about 32 and backfires like mad. Symptoms are the same in open or closed loop.

Recently, I was running well but had low oil pressure. I rebuilt my oil pump (involves pulling the dizzy), now have awesome oil pressure but these symptoms. I have not verified my TDC marker since the oil pump rebuild and plan to do so soon but was also going to throw a module at it while I was in there.

Anything else I am missing/should consider?

I thought the 0E cal's had 4 degrees initial timing. This can be changed in the cal to whatever if you need more initial timing and also you want that value to match so what you're commanding matches.

(BJKZ)
;---------------------------------------------
; SPARK ADVANCE CALIBRATIONS
; TYPE $0E
;---------------------------------------------
L4132 FCB 11 ; 3.8 Deg, INTIAL SPK (256/90)
; (This val is sub'ed from total spk adv)

I take that back, I just found a cal (BJDR) that has initial spark at 0, so maybe that it what you started with?
;---------------------------------------------
; SPARK ADVANCE CALIBRATIONS
; TYPE $0E
;---------------------------------------------
L4132 FCB 0 ; 0 Deg, INTIAL SPK (256/90)
; (This val is sub'ed from total spk adv)

When it starts backfiring, is it out the exhaust or out the intake?

P.S. Fast, do you happen to know the part number of the marine module?

[rang-a-stang]

When you are looking at an OEM junkyard module the 369 and 048 will clearly be stamped on top. Many fullsize G-vans got the 369 module in either a 4.3 or 350 V8. A lot of the TPI cars had the 369 as well but those are much less common then the vans in the wreckers.

As for your issue, for older slower burning heads it sounds like you may not have enough timing advance. Retarded ignition timing can cause the engine to backfire. What was it timed at prior to the distributor being removed? I have not messed with a 401, but I have a 304 and a 360. Both of them liked 12-16* of initial advance with 22* centrfical from the HEI and about 10-14* vacuum advance. At 3,000 rpm with the vacuum connected it is not uncommon to run 50-56* of timing. Not knowing what you have for a timing map its hard to say what your initial should be set at. If it is still a stock GM TBI timing table, I would bump your initial advance up to about 12* and test what happens. The AMC V8s usually make best power with 36-38* of timing advance and a stock TBI truck rarely has more than 22* at WOT. Also the timing maps on the GM TBIs have a very slow advance rate and often negative timing values at high kpa and low engine speed.
Copy (number stampings).

Timing has been set the same before and after dizzy change (at TDC). I am still running the stock GM TBI tables so I will try your advice and bump to 12'ish and see what happens. At this point, I am not worried about making tons of power; I just want it to run in a way that I am fairly certain everything is "working". If I advance my timing to 12 and the backfiring goes away, I know it's poor timing settings. If I advance to 12 and it still backfires, I may still have a faulty module or my marks may be off.... right?

I thought the 0E cal's had 4 degrees initial timing. This can be changed in the cal to whatever if you need more initial timing and also you want that value to match so what you're commanding matches.


(BJKZ)
...
I take that back, I just found a cal (BJDR) that has initial spark at 0, so maybe that it what you started with?
...
When it starts backfiring, is it out the exhaust or out the intake?
...
I started with BMHK and have not touched any of the timing settings. In TunerPro RT my initial advance is set to 0. I also thought I read it somewhere else that this BIN is set to 0. Hm. Guess I better dig and make sure.

Backfires out the exhaust. Not sure if it matters, but I am still running my stock Duraspark dizzy, that has been welded, and the stock hall sensor is wired to my module. I have tried both a tall cap and the Ford wide caps with the same symptoms.

[rang-a-stang]

Got home from work, advanced timing by 15 degrees and it stumbles, pops, and barely idles. Retarded the timing about 15 degrees and it won’t idle at all.

[rang-a-stang]

IT WAS MY D@MN ROTOR!!!!

I have a buddy here in town that has another AMC 360 so I took my cap/Rotor/wires, and adapter (we run the Ford Duraspark wide cap) and went to his house. Intalled my cap/wires, his truck fired right up. I installed my rotor and adapter, his truck would barely start. Put all his parts back on except left my rotor and it backfired and sputtered just like mine. So I took all my parts home and borrowed his rotor and put them on my truck. It fired right up and ran like a champ!!!

Now on to tuning! It was in closed loop pretty much the whole time and that is new too. WOO HOO!!! Thanks everyone for helping out!

[In-Tech]

Awesome, I've seen quite a few that burn a minuscule hole through the rotor and sometimes idle fine but under load it takes the fire right to the shaft. Good testing. :thumbsup:

[rang-a-stang]

Check this out! this is what the killer was! The indexing tab INSIDE the rotor was off about 10 dergrees! Here's the bad one:
14378
Here's the good one:
14379

[PlayingWithTBI]

WOW, nice catch! :rockon: Which brand is which?

[rang-a-stang]

I have NNNNNooooo clue. I bought the bad one about a year ago and it was sitting on my shelf. The good one was my buddies he got from a wrecking yard.