Is this serial number 0F821387 a Thunderbolt IV ignition or not?

[rhillman75]

A previous post from another member said that I do not have a Thunderbolt IV ignition on my 1996 Mercruiser 4.3 LX Gen +. Now I am a little questionable... considering my plastic housing has "Mercruiser 4.3 LX Gen +" on the decal and I do have a purple/white wire with a female bullet connector coming from the factory harness, not to mention that the marina "said' that that wire has to be grounded for "base timing!" All I know is that it is a 1996 Sylvan V196 with the original engine and nothing to my "knowledge" has been changed. I have been all over the engine compartment and I do NOT see ANY computers or anything! Is it possible that this engine has been tuned and the purple/white wire has been grounded for the wrong reasons/motor assumption? If anyone does have answers... please feel fre to chime in with timing, neutral rpm, in gear rpm, etc. Now I am scared because the marina set the timing to that of a Thunderbolt that needed 10 degrees to correct as they seen it! Are there any signs that I can tell whether this is 4 or 5? This engine does have a Mercarb 2 barrel on it.

 

[John_S]

Re: Is this serial number 0F821387 a Thunderbolt IV ignition or not?

Under Mercruiser parts for that serial number, shows icm's that are T5. That is what I would have expected given the rough years you mentioned, and having the purple/white wire. Module should be mounted on the distributer. It does have to be in base mode for initial timing, idle mixture, and idle speed adjustments. I don't have a V6 SM right here but I believe 10BTDC is the correct timing. Idle speed 650 in neutral? Someone will chime in with exact.

http://www.mercruiserparts.com/sele...4.3LX+(GEN++)+(2+BBL.)+++GM+262+V-6+1996-1997

PS: Here is a '94 Service Bulletin on T5: http://www.boatfix.com/merc/Bullet/94/94_02.pdf

 

[Don S]

Re: Is this serial number 0F821387 a Thunderbolt IV ignition or not?

Does your distributor look like this?

 

[rhillman75]

Re: Is this serial number 0F821387 a Thunderbolt IV ignition or not?

Yes it does look like this.