Triumph/TR3A Projects:Tuning Carburetors
First I topped off
the carburetor with oil
Then I pulled the spark plug.
That's fouled!
I put the colortune in,
and got a very yellow spark. Way too rich, and hence the fouling.
Here's a video of the colortune
in action, showing the regular yellow spark. I was actually surprised at how slow it was blinking, but I guess 600 rpm for 4 cylinders is only about twice a second spark. [Video, 1.9M]
I adjusted the richness
on the bottom. There's a spring maintaining the adjustment, which seems a bit slippy, and probably explains how it easily gets out of tune.
And presto, the spark turns blue.
I tuned it to where the spark just starts to turn blue.
Tuning method #2
(suggested by Haynes Manual) is the lift method: using a wire, lift the carb cylinder up a small amount, and it should just slightly increase RPMs if it's in tune. When I tuned it to the colortune, it would actually decrease RPMs under the lift test. I trust the colortune, and I don't have a problem with acceleration, so it seems to work.
Then try to match vacuum
between the carbs. This proved difficult. I have a vacuum gauge, but it would generally go off the chart even at low RPM, so it was impossible to match. I tried doing it by sound instead, but I couldn't distinguish much difference between the hiss.
To adjust, disconnect
the connecting bar and set the idles, then reattach the connecting bar with it just pressing up against the idler. Pretty easy once you've found the right spot.
Created with the tool album generator from MarginalHacks by D. Madison on Tue Jun 2 14:41:29 2015