0435 lycoming runs awful

[Insta-gator82]

My work boat is a 13 ft Combee with an 0435 Lycoming on it. It has never really had enough power to push the boat like it should. Now I'm having trouble getting it to run over 2000 rpm. I really don't know much about this motor. I'm going to change out the plugs tomorrow, but we've been running it on 93 octane with additive. Would running a/v gas in it help? Any other ideas? I would like to fix this myself, if I can. Thanks.


Greg

 

[marshmaster pat]

Starting with new plugs is an idea. While you have them out, get your hands on a compression gauge and check all the cylinders. I would bet you either have low compression on your cylinders or you have terrible compression on a couple.

Av-gas will not help it turn more RPMs, however, it may help it run alittle cooler.

 

[cowboy]

Insta-gator,
Check that compression like Marshmaster suggests. Look at thise plugs while threr out, and read them for color. Also look for high wear on the electrodes.

If they are white, and the tips burned off, then it might be a fuel problem.
Fuel pump going, plugged up jets, ext. Might be the next place to look if the comp checks show decent results.

 

[Insta-gator82]

Thanks for all the help Marshmaster and Cowboy. I think I know what my plans are for this weekend.....

Greg

 

[Insta-gator82]

Also, what plugs would you reccomend? and what range should the compresion be in? I'm used to working on Big block mopars, so this is all new to me.

 

[marshmaster pat]

That is a different beast, I am used to the 0-540.

Using Champion D-16 or Denso L-14U (or 5000 - new part number).

Call Jr. Jurnigan's and ask him what he suggests.