Webber

[katsi]

Guys, I swapped out the carb for a new 34/36 dvaf or whatever the correct replacement carb is supposed to be and I am having a terrible time getting the idol to stay put. Sometimes it's perfect and other times it's high and then low and then just right. Anyway it ranges between about 200 rpm's and 2000 rpm's. I can adjust the idol screw at different points but I am getting tiered of adjusting it after every start. Can anyone help?

Also - my linkage is flowing fine - that is not the problem.

[baltobernie]

When the engine is idling fast, can you "blip" the throttle and make it return to normal?

[katsi]

When the engine is idling fast, can you "blip" the throttle and make it return to normal?

No, the throttle linkage and cable are working properly. Yes, I am loosing about a 16th of an inch in the wide open position but the throttle cable and linkage is OK. The loss is due to the angle of the carb to the throttle linkage. It just wont turn anymore towards the engine as it gets to the point in the rotation where it want's to start moving in a downwardly direction in order to complete the total throttle movement on the carb. On the 79, the throttle pulls in the opposite direction than the earlier models. So, Unless I want to re-vamp the throttle cable, I'm kinda stuck with it this way. Yet, it does not affect the idol speed. I can not figure out why it is so random and varriable.

On the plus side -
Backfires have stopped.
Rough idols at any speed have stopped.
It will actually keep running without the tack registering any RPM's but you can tell it want's to stop.
Cold starts are easy - all starts are easy
No more cranking to get the fuel from the tank to the carb.
Very smooth accereration and decellerations.

[baltobernie]

Is it a new carburetor?

My only other guess is a vacuum leak. It doesn't take much of a gap or hole anywhere to send the idle crazy. Block off all vacuum lines, see if that changes anything. Next, spray some carb cleaner around the base with the engine running.

[tartan18]

My DFEV 32/36 replacement carb was doing the same thing (variable idle). I hooked up a vacuum gauge and confirmed that because the needle was jumping around at the 15psi mark, which is where I got the smoothest idle by adjusting the mixture screw, that I had a small vacuum leak. Spraying with carb cleaner led me to the leak's location (intake manifold gasket just behind the carb). Tightened the intake manifold and all was well.

[katsi]

OK, thanks guys. I will give it a test and let you know.