Thunder Bolt IV ignition timing question

[tfret]

I have a 1984 5.7L 260HP mercruiser (mcm260 I think). The previous owner upgraded the ignition to the Thunder Bolt IV electronic system. The manual calls for setting the timing at 8 degrees BTDC and to simply point and shoot the light at idle speed. I'm a bit confused because I've been told by other boat owners a jumper wire must first be installed before checking the timing. Perhaps this is for other ignition systems (?) I'm not sure but just wanted to check here to be sure. Especially since this isn't the original ignition system on my engine.

 

[Don S]

Re: Thunder Bolt IV ignition timing question

TB IV is point and shoot, TB V is the one that you need to put in base timing mode.

 

[achris]

Re: Thunder Bolt IV ignition timing question

I have a 1984 5.7L 260HP mercruiser (mcm260 I think). The previous owner upgraded the ignition to the Thunder Bolt IV electronic system. The manual calls for setting the timing at 8 degrees BTDC and to simply point and shoot the light at idle speed. I'm a bit confused because I've been told by other boat owners a jumper wire must first be installed before checking the timing. Perhaps this is for other ignition systems (?) I'm not sure but just wanted to check here to be sure. Especially since this isn't the original ignition system on my engine.

No... That engine came out of the factory with Thunderbolt IV on it....