TR4/4A Strombergs...wont idle unless choke pulled out?

[karls59tr]

I realize that there could be many reasons for this to happen but what would be the most common one or the first thing on the carbs to check? All my experience is with SU's.

 

[poolboy]

Do they rev up normally ?

 

[Geo Hahn]

First thing I would try is increasing the idle speed with the two screw stops for the linkage.

On ZS carbs pulling the 'choke' does two things - slightly increase the idle (uses a cam) and slight lift the carb pistons (uses the start bar - a shaft with a flat on one side).

To set the idle I would first assure the carbs are balanced (adjust them w/ one of the screw/bolts on the accordion connector loosened) then tighten it up when they are balanced and the idle speed is good.

Beyond that there are many things you might check - timing (changing timing due to points wear or slipping), examine carb diaphragms, mixture, float level & float condition, etc -- IOW a complete tune-up.

But if the problem is simple and slight an idle adjust may get it done.

 

[Marvin Gruber]

Has the car sat for a while and not run? The bass needles corrode very easy. Look and see if needles are green, if so clean with scotchbrite pad or fine sandpaper.
Marv

 

[karls59tr]

Has the car sat for a while and not run? The bass needles corrode very easy. Look and see if needles are green, if so clean with scotchbrite pad or fine sandpaper.
Marv

Yes the car has been sitting for 10 years. I will clean the needles. How difficult is it to access them?

 

[Marvin Gruber]

Karl,
not hard at all. There are four screws on top of the dome of the carb. Unscrew them, remove damper rod where the oil goes. Maybe tap domed upright with hammer to break loose the dome and lift it up. You will see spring and black rubber diaphragm. An old torn diaphram maybe your problem as well. Look for any tears in the seal. Gently pull on the upright pipe to lift it all out. Needle will be underneath.

Marv

 

[poolboy]

 

[glemon]

Check to make sure the rubber diaphragm (as shown on the piston above) is not torn, common problem with the Stromberg, easily remedied with a new part. Other than that diaphragm they are very similar to SUs in operation and adjustment (the choke is set up different as well I guess). That and check for vacuum leaks.

Have messed with the idle speed adjustment?, screws that adjust where the throttle shaft stops.