6hp 1960’s rich at high speed

[johnyrude200]

We’ll certainly see by end of day. Ripping apart a pontoon boat the first half of the day for a project of mine, then hopefully fixing this 6hp. I will say the timing cam was so worn on this one and the cam follower (off the carb) had about 1/8th worn away on that black plastic piece.

Not saying these things are inter-related, but this motor has had to had a lot of use for it to be worn that much. Never seen one worn away that much (replaced both parts already and it didn’t make a difference).

[johnyrude200]

So, there is something wrong with this carb. I swapped out carbs with another known to be good 6hp carb and the motor ran totally fine.

I’m scratching my head here though. Before swapping out with a known good carb, I switched the bowl and high speed jet, and had the same issue. I have the rest of the carb set, to my knowledge, correctly. I’m trying to figure out what I’ve missed here. Float is set right, replaced the boss gasket (in the center), and again, it appears the high speed jet is OK.

Motor bogs down at anything much above idle because it’s getting way too much fuel. FLEETWIN – if you are going to the meet this saturday I’ll bring the carb with me and maybe you can make heads or tails out of this one. It has to be something obvious that I’m overlooking.

[fleetwin]

Yeah, will be there.
I’m guessing there must be the aluminum nozzle wall is damaged/porous, allowing extra fuel to bypass the high speed jet. But, how about the brass nozzle? If that is damaged/plugged, that might create a rich condition as well.

[johnyrude200]

I’m just going to bring it down. Are you bringing a boat? I’ll be sporting my really nice ’67 20hp johnson (2nd owner). I had a 6hp a month ago that had such high compression, you had to use the choke lever to shut the motor down.

This 20hp, I measured at 150PSI COLD – yes, I’m not kidding. And I obviously am doing these tests regularly on all these motors – haven’t seen even a 25hp much above 130-135PSI yet, so this one is a keeper!

[johnyrude200]

So figured out what the problem was. That lead shot you were trying to remove actually wasn’t supposed to be there in the first place. I took a look at a couple of other 6hp carbs and the other two I have did not have a shot in that orifice; this is why it was running so rich.

I’ll make a note to do a side by side comparison moving forward in these situations moving forward. Whoever worked on it before plugged up the wrong hole inadvertently.

[fleetwin]

Great, I’m glad we figured it out and you don’t need another carb or the expensive lead shot!

[billw]

That was a fun thread. Thanks for letting us know the outcome. I have always said that the hardest things to trouble shoot are things that another human mind has messed up.

Long live American manufacturing!

[johnyrude200]

As the saying goes, "fixing it isnt the hard part, it’s finding out what the problem is."

If you want to see what I was dealing with, get your motor running. Put your finger over the little hole on the top of the carb on the starboard side. It’ll bog down, shake, & smoke like hell with any RPM much over 1/4 throttle.

Of course, watch out for that flywheel!

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