I Played With My Carbs Yesterday...

[texasz]

Well I finally had a bit of time to play with my carbs yesterday. As some of you may know from a previous post, Running Like A Dog Today, I was having some problems with the way the car was running. Bottom like is that it was running very rich. The plugs had about 3 hours of running time on them and were carbon fouled like you wouldn't believe (black, black, black). I got new plugs and printed out the instructions from zhome.com on how to tune your SUs and took three of my repair manuals out to embark on trying to fix the problem.

Now I know that I did not really fix much but was fairly pleased with my results considering that this was my first run at messing with carbs. The car used to backfire ALL the time. I got that resolved (mostly). I do not think that I have the mixture right nor do I think that I have the carbs balanced. However, I did find that the knarled nut with the ball on it under the carb was only turned 1/2 turn down from the carb!! From what I have read it should have been 1.5 to 2.5 turns down as a starting point to tune them. I turned it down more and the backfiring stopped! The only time it backfired after this was when I pressed on the gas then started it.

It seems as though the plugs are stilling fouling up but I think that I'm getting closer. I too the car out for a drive and it really seemed to drive, accelerate, and idle better now that it was getting more gas. However, it is still running rich I think. I really need to find a color tune to help me with this. Anyone know where I can find one?

Also, I bought the Syncrometer from MSA instead of the Syncrotester and am not sure that this was a wise move. All of the documentation references the Syncrotester and where the floating ball should be but there is nothing to tell me how to use the Syncrometer. Should I write off the Syncrometer and just buy the Syncrotester or can someone help me to figure out how to use the Syncrometer?

As an additional request, if there is anyone in the Austin area willing to help me learn how to tune my carbs I would really appreciate it.

[Daniel]

You have to follow the steps exactly to set tune the carbs.I'm glad to read that you're not afraid of them and are more familiar.I followed the haynes book instructions for years and one day it was like the light bulb came on and I understood the need for each step.As for the center of the sync gauge.I would assume your meter would need to be in the center also,thats a guess.I would keep perfecting your skills on the tune.A colortune my help but if you are just turning screws and knobs hoping to get it correct I doubt it would provide much benefit.No shortcuts,Take the steps from the top and keep practicing.Thats how everyone else learned.You can't help but get better each time!AS for the knarl nut.Remember the needles that are attached to the piston are like a "v" they seat into the tube that the knarl nut raises or lowers.The lower you go the more fuel is give at idle.The more you raise it the deeper the needle goes in and therefore less fuel is given at idle.Thats why the choke causes the tubes to drop.That makes it richer..When the car is given the gas the pistons rise so high that at that point the knarl setting has little effect.Thats when the other adjustments come into play.

[Daniel]

Sorry for getting long today.The meter will have an adjustment on it to vary the flow to the gauge.This will allow you to "tame"the meter to the middle range.When doing faster rpm test you do it again because you are pegging the meter with more airflow.Did you take the tops off "the carb bells"and clean the piston and housing?Nice to start fresh or you'll do it often.

[Victor Laury]

I don't want to come off as a Know-it-all, or "high and Mighty" But, adjusting the carbs is absolutely the very last step in tuning the engine. If your adjusting the carbs without performing an orderly tune up, your setting them to compensate for other items that are poorly adjusted.

#1 Points condition and gap

#2 rotor and cap condition

#3 Timing

#4 Spark plug cable condition

#5 Spark plug condition and gap

#6 Valve adjustment

#7 fuel supply filters and pressure

#8 carb float adjustment

#9 carb idle mixture

#10 Carb Balance

This is the checklist I use with success.

[texasz]

Victor,

As I mentioned much of the history of what's going on is located in another thread which I provided a link to above.

However, to help a bit here's some of the info.

#1 Points condition and gap

No points, it has an electronic ignition.

#2 rotor and cap condition

Appears to be in good condition.

#3 Timing

Timing was set.

#4 Spark plug cable condition

Plug wires are pretty new and in good condition.

#5 Spark plug condition and gap

New plugs were gapped yesterday just before installation.

#6 Valve adjustment

I have not done this nor do I know how.

#7 fuel supply filters and pressure

Fuel filter is new.

#8 carb float adjustment

Could not find the window to see what the float level was.

#9 carb idle mixture

As stated above, this was one thing I did yesterday.

#10 Carb Balance

As stated above, this was one thing I did yesterday.

I hope this helps a bit.

[beandip]

to clear up a statement made earlier . the mixture adjustment is not just at idle , it effects the fuel mixture all the way to full throttle. This is one of the great things about these carbs.. Victor youre right on the money , just adjusting the carbs and not setting the timing , plugs and valves is adjusting the carbs to cure another weakness. texasz another thing to check is look at the setting of the choke cables and make sure that they are not sticking also if the fuel lines that attach to the adjusters are not stiff and brittle this will cause the choke to stick . Do not use vacume hose to replace these lines. recomend dealer or ZTherapy . usual fuel line from a parts store is too stiff. I have herd of fuel line from a Cycle shop working . Good luck gary