Smoking carburetor Volvo AQ170(Solex PAI 44)

[HorizonblueDK]

Last Saturday I synchronized the triple carb setup on my Volvo AQ170 B30 engine. Ran the engine warm first, took off the flame arrestor and started adjusting according to the manual. I noticed that a little smoke came out of one of the carbs (with the engine off). Thought that it was just a coincidence. But today when I took a small trip and checked the engine, I could see a little smoke coming out of the flame arrestor, with the engine off. Probably from the same carb.

What causes this smoke ?

 

[500dollar744ti]

My guess is lingering PCV gasses escaping up through the flame arrestor as the engine cools.

 

[HorizonblueDK]

Maybe, but the first time I saw it, it came up through the barrel of one of the carbs. Is that one leaking ?

 

[midcarolina]

If it's coming out of the one carb repeatedly I would guess you have a issue with valve timing or intake valve not closing on one cylinder..........But I'm no engine expert...........

 

[Pesimist]

Some amount of vapors, gases, or light amount of smoke coming from the carburetor occurs on all engines when when you shut them off. Wouldn't waste anytime looking at intake valves or timing unless you know something you haven't mentioned. On a six-cyl engine one or more of your intake valves will be open partially or all the way when you shut it down.

 

[HorizonblueDK]

The only issue I'm having with the engine, is that it vibrates just a little(running rough I guess), every 2 seconds or so. Easy to start, idles great. Did a compression test, 5 cylinders showed 145 PSI and number 3 cyl showed 118 PSI. I don't think that causes the vibration (rough running). I suspect that there is something wrong with one carburettor. As mentioned before, they are synchronized according to the original manual.

 

[HorizonblueDK]

The spark plugs are not new, but looks good. Ignition wires, rotor and cap are new. Electronic ignition and new coil.

 

[midcarolina]

Is the #3 cylinder fed by the smoking carb?

 

[HorizonblueDK]

Is the #3 cylinder fed by the smoking carb?

I have forgotten if it was carb No 1 or 2 that was smoking. Carb No 2 feeds the cylinder with lower compression. I will check next time I go boating.

 

[HorizonblueDK]

Yesterday I took a trip and removed the flame arrestor afterwards to see which carb was smoking. No smoke at all.......

Thinking about it, maybe cyl No 3(with lower comp) is causing the engine to shake a little afterall. When I took the test, it did take some time, before the pressure was build up, longer than the other cylinders.