thunderbolt IV module question

[kinger952]

i have acess to a 4.3 module -- the guy i am getting this from says and tells me it WILL work for a v-8 350 1984 - this is the oldstyle alum box type - i didnt thing these were around when the 4.3 came out ? is this true and even if it is the newer style ( plastic) will it work properly for a 350 v-8 ? i will have to find a harness if it is true
i dont see how it will work from 6cyl to 8 cyl ? but i am not too smart either

 

[Scott06]

i have acess to a 4.3 module -- the guy i am getting this from says and tells me it WILL work for a v-8 350 1984 - this is the oldstyle alum box type - i didnt thing these were around when the 4.3 came out ? is this true and even if it is the newer style ( plastic) will it work properly for a 350 v-8 ? i will have to find a harness if it is true
i dont see how it will work from 6cyl to 8 cyl ? but i am not too smart either

Yes and maybe

Yes the sensor in dist is just a trigger module doesn’t know if it is firing 6 or 8 times a revolution . I repowered from a 4.3 to 5.0 and ran the engine with a 4.3 module until I could find a 5.0 module. This was with a TB 5 but would figure the four would be same

Maybe because the advance will be different usually the 4.3 s have less advance than a 5.7. Usually the tb4 modules are marked v8-24 or similar means v8- 24 degrees. So if using a V6 module you may need more
Initial timing to get total advance up

 

[newtoboat101]

i only know a little about tb4,is it on exhaust? look on tb it will have numbers on it thats your advance . make sure the 4.3 and the 350 advance numbers are the same then it will work its either 22 or 24, just as easy,dump the TH4 and buy a delco est ignition system

 

[kinger952]

Yes and maybe

Yes the sensor in dist is just a trigger module doesn’t know if it is firing 6 or 8 times a revolution . I repowered from a 4.3 to 5.0 and ran the engine with a 4.3 module until I could find a 5.0 module. This was with a TB 5 but would figure the four would be same

Maybe because the advance will be different usually the 4.3 s have less advance than a 5.7. Usually the tb4 modules are marked v8-24 or similar means v8- 24 degrees. So if using a V6 module you may need more
Initial timing to get total advance up

Hi. Maybe I said it wrong. I'm wondering about the EXTERNAL module above the rocker cover if this is usable for that one

 

[dubs283]

Hi. Maybe I said it wrong. I'm wondering about the EXTERNAL module above the rocker cover if this is usable for that one

Like Scott said, yes/maybe?

Don't know much about the old large box, riser mounted units. I see a few of them these days but can tell you rn I don't trust them. Look at the back, potted side of the module, is it cracked anywhere? If so, move on, 50/50 chance of it lasting much longer if it even works properly/at all.

You can upgrade to a Delco est/hei ignition system for about $1200 list from merc. Just gotta rewire a few items and drop in the new distributor

 

[achris]

All V6 modules are 16 degree maximum advance. They are also expecting only 3 pulses per revolution and a V8 generates 4, so at idle (600rpm) the V6 modules is expecting 1800ppm. But the V8 will generate 2400ppm, so the V6 module thinks the engine is doing 800rpm. A V6 module on a V8 will apply the advance much earlier.

Chris ...

 

[dubs283]

A V6 module on a V8 will apply the advance much earlier

I know this to be true with next generation (plastic housing) style modules but afaik the older style may or may not have mapping for advance from v6 to v8. I would guess not, I was told many years ago by a fella who's forgotten more about boats than I can learn a v8 stamped module will work with sound performance on a v6 but not vice versa. This is in reference to the plastic housing module not the older, larger, " box" style module

As I said earlier, I do not trust any older box style, riser mounted module. Years of heat and use have deteriorated them to the point of eminent failure. Not to mention they don't get along with three wire sensors at idle timing

 

[achris]

I know this to be true with next generation (plastic housing) style modules but afaik the older style may or may not have mapping for advance from v6 to v8. I would guess not, I was told many years ago by a fella who's forgotten more about boats than I can learn a v8 stamped module will work with sound performance on a v6 but not vice versa. This is in reference to the plastic housing module not the older, larger, " box" style module

The programming inside the large box and the small box is exactly the same. The only difference is the actually housing, so performance will be the same.

Not to mention they don't get along with three wire sensors at idle timing

I've replaced a few sensors on engines with the older (what I call 'Gen I') modules and as long as you run the sensor black wire to the same grounding stud that the module uses they run perfectly.

Chris...

 

[dubs283]

they run perfectly

Good info, appreciate the beta for module operation over the years.

Yet, I find using the latest style sensor, three wire fully potted with large/long ground terminal/wire with old, your definition "Gen 1" (which BTW isn't the original style module, mie 454's used a thunderbolt iii style mounted above the transmission) causes idle timing issues. Mainly the 4 degree jump up/down depending on distributor clocking. It's frustrating and confusing and makes me not trust the box style and older yet modules, ymmv

 

[kinger952]

Like Scott said, yes/maybe?

Don't know much about the old large box, riser mounted units. I see a few of them these days but can tell you rn I don't trust them. Look at the back, potted side of the module, is it cracked anywhere? If so, move on, 50/50 chance of it lasting much longer if it even works properly/at all.

You can upgrade to a Delco est/hei ignition system for about $1200 list from merc. Just gotta rewire a few items and drop in the new distributor

I was able to work on it tonight for a bit. -- replaced sensor/pickup in distributor got good spark runs very very well thru all rpm's
Thank you

 

[kinger952]

After swapping out pickup inside of distributor ( sierra part ) $20 engine runs BEAUTIFULLY!! ,thru all rpm ranges as well
Thank everyone for their help and support

 

[kinger952]

All V6 modules are 16 degree maximum advance. They are also expecting only 3 pulses per revolution and a V8 generates 4, so at idle (600rpm) the V6 modules is expecting 1800ppm. But the V8 will generate 2400ppm, so the V6 module thinks the engine is doing 800rpm. A V6 module on a V8 will apply the advance much earlier.

Chris ...

Hi. I was able to work on it for a bit tonight -- changed out pickup in distributor walla nice hot spark !! Engine popped right off and ran extremely well thru all rpm ranges with NO MISS !! Thank you for all the help

 

[Scott06]

Hi. Maybe I said it wrong. I'm wondering about the EXTERNAL module above the rocker cover if this is usable for that one

Thats what i was talking about, that is the only module.