Thunderbolt 4 Advancing Timing Too Much Too Soon

[aw380]

I have a 1988 Starfire with 260 and Thunderbolt 4. Static timing is set to 8 BTDC @ 650 RPM. Slightly increasing RPM to 675 RPM, with screwdriver, causes timing to advance to 20 BTDC (8 +12) and the RPM increases to around 950. I understand that this module should increase advance laterally, not so quickly. I tried a used module and the same thing happens.
This is a major nuisance to operate. Any thoughts?

 

[Jimway]

Check for intact advance weight springs under rotor?

 

[aw380]

Thank you for the response but the Thunderbolt 4 does not have advance weights, in the distributor. The ignition module does the advancing.

 

[Jimway]

If you have personaly looked under there (the rotor) to preclude any others from having creatively added extra/other stuff over the years, check to see that you in fact, have the correct module for that installation (v6 vs v8).

 

[Gimme Fuel]

http://forums.iboats.com/forum/engi...tting-timing-on-thunderbolt-iv-not-v-question

See if that helps. Are you sure you have a tb4? Dist Module may also be faulty. Not unheard of

 

[Wrenchmate]

I have only owned one boat that had the Thunderbolt ign. so I am by no
means a expert but I seem to remember the module letting it advance
fairly quickly or as soon as it starts getting more fuel just like you are
describing. What is your engine doing that makes you think you have a
timing issue or advance problem in the first place.

 

[Gimme Fuel]

Sounds like your TB IV is working as it should according to this:
http://www.marineengine.com/boat-forum/showthread.php?390323-Thunderbolt-IV-timing-question

Says it starts to advance around 750 rpm and is at full advance by 3700 rpm. There is nothing wrong with that. 20 degrees off idle is nothing to worry about. Makes it run smooth down low.