Hotting Up My 115HP 1979

dropbear68

Petty Officer 2nd Class
Joined
Jan 21, 2013
Messages
199
My 115 is a 79 model points dizzy black power pack it runs the one piece gear box with stainless prop, Id like get some more power from it short of stroking it to a 140 which Id do if I could find the crank n rods here in Austraya, I was thinking some Boyenson performance reeds and maybe change the prop pitch, Im fooling around with the idea of chucking the powerpack and doing the auto coil conversion but some say power can fade above 4,500 rpm due to lack of hot spark this is using a common cannister coil, how much voltage is enough? I can get a Bosch cannster coil that will throw 40,000 volts I can also use a Bosch solid state coil internally resisted good for 50,000 volts, the conversion also calls for a automotive condensor to be wired in, will the Chrysler points last? Do these motors not use a condensor with there factory systems?, any other worthwhile tricks? Carbs?
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
FrankA (RIP)used to port and polish the intake/exhaust.
​He cleaned up any rough edges and it opened up the intake and he figures he got 2-4 more hp.
Carbs: not much can be done with the exception of a bigger jet.
But your motors set up right and it probably won't help unless you bore it .030 or bigger.

​Prop changes: If your running at max rpm's 52-5500 then the prop is the right one.

I had a pair of 88/85's on my 21 and 17p props and even though it had all that power. It wouldn't get past 32mph.
I wanted more. So I got a pair of 19p props.
​I got more, 2-3 mph more and the fuel usage went up 15-18%
I changed them back pretty quick.

The only way to get MORE: bore out .030 or more.
​That big and you'll need to re-jet.
​Unload the unnecessary things on the boat.
Only run with 1/2 the fuel.
​Only 1 case of beer and only 1 dog, not the whole kennel:)
 
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