Triumph Repair: Stromberg Carb Tuning, stop screws, fuel splash

Question
Hi Howard;

Thanks again for all the helpful advice/discussion.

In the past you directed me to a very helpful procedure to tune SU carbs.  Would you happen to have a similar procedure for tuning Stromberg carbs?  

Also, if you had any other advice on the tuning of these carbs (according to your experience) I would be appreciative.

Thanks
Matt M.

Answer
The adjustment procedure is about the same on the Strombergs as it is on the SU as they are both constant velocity carburetors.

Set the throttle linkage in sync first with all the stop screws backed off, then open both throttles the exact same amount (about 1 1/2 turns on the idle stop screws). Confirm that your Strombergs have the adjustable needles (3mm Allen wrench down in the top pots) Confirm that the diaphragms are good and the pistons slid smoothly. A rough test of float level is to "Puff" with your mouth quickly at the jet hole with the piston and top pot off and you should see the fuel splash a little out of the jet hole. All that tells you is that there is fuel in the float chamber and it is high enough to run. If you have to set the float level on a Stromberg you have to remove the carburetor and float chamber.

When you have done all of that you can start the engine and warm it up (Your fast idle is backed off so you have to hold the throttle open a little to warm it up. Set the idle speed by turning each adjustment screw exactly the same each time until you have a 750 to 800 RPM idle. Then use the lift the front piston to test the rear carb for jet setting and when you adjust the needles turning clockwise richens the mixture and counter clockwise leans the mixture. lift the front piston, if the engine drops off and sounds like an old tractor, the rear carburetor is just right and if it dies, you either didn't sync the two butterflies correctly or the other carb is too lean. If it speeds up and stays fast the other carb is to rich.

Let me know how it turns out.

Howard