4.3LX TB IV timing advance issues

[Classicph5]

I have a '89-ish 4.3LX with a Thunderbolt IV module.
I was having issues that appeared to be fuel related, changed the carb to a brand new Edelbrock 4bbl, I have new wires, new Quicksilver cap, rotor and pick up (plugs aren't that old)
Boat starts and idles beautifully, shifts and idles in and out of gear with no issues. Revs on the trailer and in neutral nicely.
When I get on the throttle cold it got to wot once with no issue. Thought I had it beat. As it got warmer its like the timing advance won't keep up. Apparently new ignition modules are NLA and not sure I want to risk the money on a used one?
Is there a sure fire way to check the module timing advance or could there be another issue I'm missing?
For a test, I have pushed the timing way ahead and it ran better at WOT but still crappy getting there.
Thanks for the advice.

 

[Scott06]

I have a '89-ish 4.3LX with a Thunderbolt IV module.
I was having issues that appeared to be fuel related, changed the carb to a brand new Edelbrock 4bbl, I have new wires, new Quicksilver cap, rotor and pick up (plugs aren't that old)
Boat starts and idles beautifully, shifts and idles in and out of gear with no issues. Revs on the trailer and in neutral nicely.
When I get on the throttle cold it got to wot once with no issue. Thought I had it beat. As it got warmer its like the timing advance won't keep up. Apparently new ignition modules are NLA and not sure I want to risk the money on a used one?
Is there a sure fire way to check the module timing advance or could there be another issue I'm missing?
For a test, I have pushed the timing way ahead and it ran better at WOT but still crappy getting there.
Thanks for the advice.

I don't know the specs for you boat but you likely have a 8 dge BTDC intial setting, then somewhere around 22-24 degrees total at like 2800 rpm. Hook up a timing light with an advance feature and rev it up to about 3 k. you should see the timing advance to keep the it on the timing mark.

Other folks use a timing tape around the balancer. If you can get a advance timing light that will work. I use a 30 yr old craftsman dont need anything super high end

 

[Classicph5]

Thank you. I have a cheap timing light but it works.
I was going to go back and try to make the marks a little more readable cause they're tough to see. I wouldn't have guessed 8 BTDC but thats a good place to start.

 

[Scott06]

Thank you. I have a cheap timing light but it works.
I was going to go back and try to make the marks a little more readable cause they're tough to see. I wouldn't have guessed 8 BTDC but thats a good place to start.

do a little research and see if you can find a factory manual I might be off a few degrees from spec but should be in between the ditches... IIRC total timing should be like 22-24 degrees on it. You can do a little math based on balancer diameter if you don't have multiple marks on the cover or balancer to figure out how far the timing should move for 22-24 deg advance

Dont advance it beyond what factory is as you can cause detonation.

If you end up needing a module yes a used one or swap in a Delco EST . I bought a used one when I repowered 7 years ago works fine

 

[Scott Danforth]

Check fuel pressure

Check advance at 3000 RPM. Sould be a 20 degree advance all in by 2800

Reving in neutral means nothing. The motor will rev to 5000 RPM running on 2 cylinders with a gummed up carb

However a carb with fuel delivery issues won't rev under load

 

[nola mike]

8' initial, 22' total @2500 rpm