Colorado Boat Nut
Seaman Apprentice
- Joined
- Jul 6, 2003
- Messages
- 34
Sorry, but im going to blow up my first post, i dont have my engine serial number but i can tell you this much<br /> 84 mecruiser 120 w/rochester 2bbl(1 adjustment screw 1+ turn out} rebuilt and re-jet dropped 2 sizes from stock(solid float needle not spring loaded}<br />choke set 1 notch lean<br />point's fair cond set at about .020-.022 spec18-25<br />dwell?<br />plugs new <br />cap and rotor and wires in good cond.<br />timing- advanced, spec is 8* btdc, im at high altitude and it just wont start or run smooth at spec, so i crank it past 8* cant say exatly where<br />it's just where it runs best for me.<br />distributor springs and advance mech. seem intact and move freely, functioning properly?, i couldn't say for sure but it does advance as the rpm's increase<br />new t-stat<br />13p prop (had a 17p)<br />1.98:1 gear ratio<br />thats all i can think of for now<br />Here's my problem<br />i bought the boat 2 yrs ago it was clean and ran well on the hose but i put it in the water and it had no power/no rpm's 15-1800 max wot according to tach and my ear's<br /><br />so i started with the ignition system and set everything to spec all items appeared to be new and in good cond,<br />i also checked to make sure the carb was opening all the way and with a very minor adjustment it was.<br />with all things set i put it in the water it was still really slow.<br />also noted rich/uneven fuel mixture Smell & black smoke (uneven looking down carb wot in gear in the water }<br /><br />so this year i rebuilt the carb w/new float as i am confident the ignition system is in good shape<br /><br />you may have guessed it, it was Still really slow and seemed even richer after cleaning the carb although the carb was really clean when i tore it down <br />anyway i got some smaller jet's and a lower prop<br />i had a 17p (dia 13 1/2-14?} and went to the same dia 13P<br />the 2 helped cosiderably but im still not to the 4200 rpm id like to see<br />im around 3000 rpm tops and slow getting there (has a slight intermitant miss at max) <br />you really have to work it up slowly or it will bog fairly bad if you try to nail it<br /> also it will begain to drop off in speed as you aproach WOT about 3/4 full it just drops off bad so if you back off some you can get it back around 3K again<br />you maybe thinking accelerator pump but it's working very well<br />I just cant quite figure it out am i still rich do i need to drop a couple more sizes on the jets?<br />the plugs are carbon fouled is that from idle in the no wake zone<br /><br />i tune alot of different engines and am usually sucessfull<br />this one is being a pain<br /><br />well sorry for the long post thanx in advance for your help ill try anything at this point <br /><br />p.s I haven't done a compression test yet but i have pulled each plug wire while it was running and got a fair drop on each cyl Soooo?
I think it would go straight to 5000 if I asked it to, but haven't taken it past 4400 and probably never will. When I troll at idle (700 rpm) for an hour or so, the top rpm thereafter will be 3000-3500 until the fouled plugs clean themselves and, without changing the throttle, she'll climb to 4200 where I back of the throttle to keep at 4200.<br /><br />Checking the plugs after this, they are clean of oil, but just evenly black which I suspect is "normal". Since trolling is what we do, I guess someday I should invest in a trolling motor.<br /><br />If you've done all this then I know not what you do next. But I would double check the float level and the points.<br /><br />Good Luck<br /><br />swabbie