diagnose output port condition, carbed 6 gurus Options

[mskala]

Just getting to the valve adjust on the 914-6, found that
#4 and #6 output ports look different. #5 + all the right side,
are just carbon like from idling rich. What does #4 and #6
look like to you? Thanks for any help.

Cyl #4

Cyl #6

Others

[Carl]

Looks like oil getting past the guides to me.

[John]

I agree. It looks like oil.

[Gint]

(IMG:style_emoticons/default/agree.gif) Mine look worse than that. #6 in particular. I can actually see a small puddle of oil.

[mskala]

I guess that makes sense. Does the oil somehow limit carbon buildup
or are they also running lean (probably idle)? Whenever I set the carbs
I can get all the air flow the same, but turning the mixture screws is a
bit of black magic. (IMG:style_emoticons/default/headbang.gif)

Thanks!

[Carl]

Mark,
Explain the "Black Magic" comment. You can't get the screws to turn? If they turn there's no response?

The most common result of lean idle jets is a stumble to the engine on acceleration and spitting back through the carbs at idle.

What do the plugs look like?

I agree with your question about the oil in the exhaust ports. Ordinarily you'd be trailing smoke with any significant quantity of oil leaking past the exhaust guides and you'd see carbon in the port. So, it could be lower temps in those cylinders due to ?? guessing here -> can't be running lean since that's hotter and oil would burn so, maybe these cyls are running rich and the oil is providing enough of a coating that the carbon is not sticking to the port walls they way it is in the others?

[Gint]

Check for an air leak. Infamous worn throttle shafts most likely. Mine are going to Eurometrix.

[mskala]

What I mean is that you're supposed to first assume that turning
all the mixture screws the same amount from closed will be
pretty much the same. Then turning them until max rpm, it's not
easy since the rpms are changing a little all the time anyway. And
you won't see the results until looking at plugs or ports.

I don't like to pull plugs, especially before valve adjustments.
Haven't looked in a year (~4k miles)

[Carl]

Mike's got a good thought. If the shafts are leaking air (as mine do, also) the idle doesn't want to settle down much.

It's pretty tough to set the idle mix if the idle isn't steady. Did you try squirting some carb cleaner around the shaft ends?

Just out of curiousity, do you still have the stock venturis in the carb? Mine had been changed to a larger size a long time ago and I recently swapped them back. It's interesting the change that it's made to the engine at idle. It doesn't make logical sense but the engine seems to be better behaved even at idle.

[krk]

Carl,

You swapped out your primaries?

kim.

[J P Stein]

A couple of thoughts......which seldom have much worth. (IMG:style_emoticons/default/laugh.gif)

Look at the plugs. Usually, the plug will confirm what the light colored valve is telling you....lean....maybe too lean.....or maybe they all should be that color (IMG:style_emoticons/default/confused24.gif) I prefer rich...all things considered.
Not the most power ("if you wanna be mean, ya gotta be lean"....name that old time drag racer), but safer.

Carb tuning is a black art till you understand how to do it....then it's merely voodo. I keep a supply of chickens.....couple of frogs...oh, nevermind.