thunderbolt iv 4.3 with v8 22 degree advance module work ?

[yodacrawler83]

i bought a 90 chaparral with a 4.3 merc and a 2br carb and thunderbolt iv ignition . but i was just looking at it and noticed that it has a v8 22a module on it instead of a v6 module. Will this module work ? it seems to run fine with it on there . it must have been that way for a while because the previous owner ran it this way . has anyone else ran this module ? and will it cause any problems ?

thanks for any input on this !

mike

 

[achris]

Re: thunderbolt iv 4.3 with v8 22 degree advance module work ?

.... will it cause any problems ?

Hi Mike,

Yes, that module will cause major engine damage. It gives 22? of advance whereas the V6 module gives only 14? of advance. With the V8 module on that engine you run a very serious risk of knocking holes in your pistons. The part number for the right module is -15247T01. Unfortunately it is a very spendy little item, but still cheaper than a rebuild.

Chris.........

 

[Don S]

Re: thunderbolt iv 4.3 with v8 22 degree advance module work ?

One other note, you can convert your ignition system to the Delco EST distributor cheaper than buying that IC module for your Thunderbolt.

 

[yodacrawler83]

Re: thunderbolt iv 4.3 with v8 22 degree advance module work ?

thanks guys . i actually have the right module on a old boat sitting in the back and i pluged it in and fired it up seems to run better. and i shot the timing in and seems to fire out of the hole real nice . just wont reach wot as it wouldnt before either . before it would only reach 3800 the motor is freshly rebuilt punched 60 over and heads were redone along with the carb . im running around 40 mph at 4000 rpm trimmed up and i do have one of those hydrofoils on it dont know if that affects it or not . it has a 19p x14.25 any suggestions ?

 

[achris]

Re: thunderbolt iv 4.3 with v8 22 degree advance module work ?

You need to be pulling 4400-4800 from that engine. If you're only getting 4000 with a 19" wheel, then try a 15". Rule off thumb is 200 rpm for each inch change. You need 600 rpm, so 3 inches. Props only come in 2" increments, so go SMALLER. You should be up close to 4800 with that. You're better off slightly smaller than slightly large. Less load on the engine, better hole-shot, and better holding of engine speed when running into or with a large swell.

As an example, I run a 17" prop. At WOT I bounce on the rev-limiter (5100), but at cruising the boat is a lot better than with the 19". I also have a fuel flow meter and can tell you that it doesn't matter which prop I run, for the same boat speed the fuel consumption is exactly the same.

Chris......