ThunderBolt IV

[Jim]

Can anyone verify that a 1987 7.4l 330 hp Thunderbolt IV ignition module is the same as a 5.7l. I'm trying to pick one up used
and I thought the timing advance was different between the modules but someone
is telling me that they are the same.

[marcdups]

Jim, according to mercruiser parts catalogue, the 87 5.7l engine has 3 different modules depending on serial #'s, part #'s are 15899a 1, 814125a 1, 814295a 1.the 7.4l 87 model has what they call an ignition amplifier part # 390-7804a 3, and the 88 7.4 liter has what looks like a module but still call it the same but different part #'s than the 5.7l, # is 15248a 1. If you have the serial #'s of both engines we may be able to cross reference.

Marc

[Jim]

Marc,
Thanks for the information, I did find a parts list on the internet and I show the part number to be 15248A1 Superceded from 390-7804A3. I will get the S/N tonight but do you know if the module has the part number on it?

[marcdups]

Jim, see what your module has stamped on it, it will be either V8 24 or V8 20R or V822 or V8 24 S they all seem to be different!!!

Marc