Questions about rebuilt powerheads.........

[Theoutdoorsman]

Should a slight difference in horsepower be expected with a .030 over piston change on all four holes. Just curious as to weather or not I might need to consider a change in prop size after this rebuild is complete. My current prop was turning about 5600-5800 rpm's, prior to pulling the powerhead, and all depending on my load. I would assume not, but the thought did cross my mind as I'm not sure how much, if any, this would affect the hp of the powerhead. Also, with the change of the piston size, what are some things to consider in terms of preventative maintanance and care? Any additional steps to consider? Obviously, the occassional decarbing of this rebuild using SeaFoam is of the utmost importance. Can this be used as a fuel addative along with Stabil and run through a water seperator without any problems? Sorry for all the questions.............Thanks in advance..................ALAN


1979 Evinrude 140hp

 

[Dhadley]

Re: Questions about rebuilt powerheads.........

You won't see any hp gain from boring .030. In fact I've had guys want me to bore their crossflows from standard to .064 over to gain hp and they never do.

 

[Theoutdoorsman]

Re: Questions about rebuilt powerheads.........

Thanks Dhadley. What about the mixing of the SeaFoam and Stabil with the fuel/oil mix and running them through a water seperator........see any problems there? It's not going to filter these addatives out is it?What about the temps of the rebuild during operation.......any noticable change to be expected? I would assume higher temps are to be expected because of the additional metal cut from within the cylinders. Would I be wrong to assume this? I can't help but ask this, but approximately how far can these blocks be bored? You mentioned .064.........just curious what the max is.............Thanks!!!