RUNNING RICH and how to adjust

[john chalk]

OK so fiddling with the climate control means I have had to idle the engine for an extended period resulting in a large black sotty mark on the driveway and fouled spark plugs.  cleaned the plugs and washed down the drive but is this an indication of rich mixture and if so is there an adjustment for mixture on the carter carbys?  have not looked in the service manual thought I would put it out here for comment first.

[David Thomas]

The factory knew there would be some slight vacuum leakage in the HVAC controls. That is why they wanted the carburetor adjusted with these controls working and the A/C turned on, adding load to the engine. That way, you compensate the vacuum leakage with the idle mixture screws, otherwise if adjusted with the A/C off and disconected from vacuum, when you reattach the HVAC vacuum lines you will have a lean mixture at idle. You also need to adjust the mixture and idle with the car in drive, that is why the emergency brake line is to be removed, plugged and the brake set. Myself, I don't remove the line or use the emergency brake to hold the car, I securely scotch the wheels so the car will not move, forward or backwards, while I adjust the mixture and idle rpm. If the idle is more than 480 rpm in drive with A/C on, you can overheat the transmission when at idle, especially with the A/C off. It's all in the shop manual.

As Art stated the TV rod and Throttle rod need to be disconnected or adjusted according to the shop manual instuctions before you adjust the carburetor. The throttle plates are to be completely closed when adjusting the idle rpm and mixture.

HTH,

David

 

[Jason Edge]

I always block vacuum at back of engine at intake and this is one area I disagree with shop manual a bit. David, when removing the vacuum lines I will say that if there is some "slack" and have not been disconnected in a while and seem stretched (almost always the case) I will cut off an extra 1/2" or so of line. If I really feel uncomfortable I will put one of those very small spring clamps on it like you see on the windshield washer nozzle sprayer lines.

[john chalk]

In regards to the vacuum comment david yes I guess blocking right at the source would eliminate all potential sources of leaks.  if I revisit this in the future I will do that.

the comfort control system is some what of a wonder to behold when it is working right. 60s technology moving all those parts automatically with the simple turn of a dial!  I used Cadillac Tims Book to help me as I did not think the service manual quite gave the drilled down descriptions of how to fix problems.. also Tim is a great source for parts for CC system.

cheers

[john chalk]

just took the spark plugs out. nice light tan colour. looks light I got it right with the mixture. that was also after idling for 10 minutes finalising the climate control repair too!

[john chalk]

thanks David.  choke is totally off. you dont need a choke here in Aus. just start engine wait 60 seconds and away you go.

since leaded fuel left Australia a long time ago all my old cars burn black tailpipes. before that you could get the nice light grey tint which told you that you had a good mixture.

all seems ok for now. I even now have the climate control working the way it should.

[john chalk]

car has been on the road for several months tony. carby was rebuilt 6 months ago. I have noticed black sooty marks where the car idles and as stated the plugs have fouled with black soot not oil. I will pull one off later today or tomorrow to see how they are now.  the caryby seems fine - no misses or flat spots.  

[john chalk]

jason no issues with the actual AC idle up - just other issues with climate control that required me to idle the car for ages thus fouling the plugs.  that seems to be OK for now but the climate control still remains a challenge!!

[Jason Edge]

...so when AC & compressor is on your idle speed up control is working per specs? I guess I"m getting confused with the comment "trying to get the climate control working properly has resulted in long extended idles".

[john chalk]

thanks gents.  carb was rebuilt 5 months ago when the intake manifold was done. trying to get the climate control working properly has resulted in long extended idles as stated. I figured as russ stated it may needed some tweaking.  we did almost 100 miles on a 1/4 of a tank yesterday. not really into economy runs with the car but car ran well ... will keep an eye on it anyway..   as I have a pilots licence I have some insight into leaning mixtures as all aircraft engines give you that option inside the cockpit although its just one simple control and you do need to be careful never to over lean any engine. slightly rich is better than slightly (or highly) lean of course.

[john chalk]

When i say idle set of course i mean idle speed