mercruiser timming

[91 boat owner]

i have a 1991 4.3 mercruiser that has the thunderbolt 4 ignition, and has a purple wire running to the coil, it from a module on the riser, do i disconnect it and set timming, and where do i set it

 

[Don S]

Re: mercruiser timming

Nope, nothing special on the TB4. Just aim the light.