Bad carburettor behaviour

[bluecoupe30!]

Well I have done a search, found out that carbs are "evil", but in my case, they usually just work fine and I don't think about them really. What happened today though, I am sure has happened to someone else, so please fill me in if you have found a solution. 1972 CS with Weber 32/36 DGAV have been working fine and I have been feeling pretty smug as I believe I have them running great, actually. Today, started fine, warmed up as usual. drove away, but needed extra pedal input to get revs up, then would gulp and accelerate. Fine on highway, but at 30-50 km/hr there is so much pedal travel before any action I thought I could tighten up the linkage perhaps. Then I noticed when turned off, linkage works fine, when running after warmed up, I can operate linkage manually, but it takes a lot of travel to get anything to happen. Suggestions? What should I be looking for here? Thanks for any suggestions. Mike

 

[Stevehose]

Is your secomdary barrel(s) of one or both carbs stuck open or not opening? Pull the air cleaners and check to see they aren't binding by moving them with engine off. Then if you have a synchronmeter check the airflow of them,there should be very little flow at idle. Rev the engine while looking at them to see if butterflies open or linkage to them is stuck.

Timing ok? All ignition/plug wires ok? Getting fuel?

 

[bluecoupe30!]

Ah, I knew you couldn't resist this one Steve! Secondaries function normally, Do not have synchronometre...yet. Believe timing good, (has been running fine), plugs, cap, wires, recent, fuel..yes! Accelerator pump perhaps?

 

[Stevehose]

I must try to defend the lowly carburetor. With the car off you should be able to see the accel pump spray into the primary barrel.

Both carbs getting fuel? Pull the fuel line at the carb and put end in a jar and see if each one fills up when cranking the engine. Disconnect the coil so the engine doesn't start.

If ok then maybe a stuck float or something clogged internaly - debris? Blast with carb cleaner. Take tops off carbs to clean idle jets. Never ends...

Ah, I knew you couldn't resist this one Steve! Secondaries function normally, Do not have synchronometre...yet. Believe timing good, (has been running fine), plugs, cap, wires, recent, fuel..yes! Accelerator pump perhaps?

 

[bluecoupe30!]

Thanks Steve.Today, I tried to free up linkages, checked for fuel pump activity, changed fuel filter...still does not operate well when warm. Linkage operates fine when car is off, but when warm, linkage will function, but no response from carbs until linkage really opened up. Hmmm. may have to start over. Do initial setup procedure again. Mike

 

[jabloomf1230]

Ah, I knew you couldn't resist this one Steve! Secondaries function normally, Do not have synchronometre...yet. Believe timing good, (has been running fine), plugs, cap, wires, recent, fuel..yes! Accelerator pump perhaps?

Try the Weber troubleshooting guide:
http://www.webercarbsdirect.com/v/vspfiles/images/Weber Trouble Shooting Guide.pdf

 

[Stevehose]

All vacuum connections tight? Carbs tight on manifolds?

 

[bluecoupe30!]

yep, tightened every nut, checked vacuum. Will have a look at the above troubleshooting guide, thanks!
Mike

 

[Stevehose]

Does it idle ok? Does it rev in neutral when working the linkage at the carbs?

 

[bluecoupe30!]

Hi Steve, sent you video
Mike

 

[Ohmess]

Check the cold start valves. If they are stuck, they could be holding the butterflies partially open which would explain why your initial throttle input doesn't do much.

 

[bluecoupe30!]

So it was mixture. Pulled plugs and they showed me the way. Re-visited initial settings and re set fuel mix and idle. Great response. Car feel like it wants to play again! I feel I can really nail this mixture thing if I acquire a precision synchronometre for these DGAVs. Many thanks to Stevehose for his encouragement and taking on the role of Ambassador of the humble carburettor!! Mike

 

[Stevehose]

lang lebe der Vergaser!