View Full Version : Where's mixture adjustment?

09-26-2003, 11:57 AM
This question will reveal my shocking lack of knowledge to everyone, but here goes anyway: My GT6+ has rebuilt ZS carbs, but they're unlike the ones in my Bentley & Hayes manuals. I can't find the mixture adjustment screws! There's a large, brass screw on the bottom of each carb (under the float bowl), however, the big screws don't seem to be for adjustment because they only screw in and out and are very tight.

Could these ZS carb be the late model ones without mixture adjustment? How may I find out --where's an ID mark on the carb to indicate the model, etc.?

Input would be appreciated! Thanks in advance.

09-26-2003, 02:19 PM
Hello Vagt6
some model Strombersgs had the access to the mixture adjustment down the main piston rod, using a long Allen key. That is, access from the top after removing the damper screw.

Alec graemlins/cheers.gif

[ 09-26-2003: Message edited by: piman ]</p>

09-26-2003, 02:28 PM
Thanks, Pinman. So, would the mixture adjustment procedure be similar to that of SU carbs?

Izual Angel
09-26-2003, 07:44 PM
Well, all the ZS carbs I know of have the mixture adjustment in the piston itself. (If it's the adjustable needle type). For a good idea what carbs you have (or should have) visit https://www.burlen.co.uk They have a VERY good database of carbs. The other adjusting screw is on the right side above the temperature compensator (next to the upper temp. comp. mounting screw). If there's no screw there, only a plugged, untapped boss then you have a later model. Some ZS's have an adjustable jet, I have no idea how that works though. I've never messed with one of those bad boys yet.

09-27-2003, 06:53 AM
Hello Vagt6,
yes, the procedure is the same, except that you are adjusting the needle rather than the jet, but the effect is the same. I am a lot more familiar with S.U.'s so I can't give you any set up references for Strombergs.

Alec graemlins/cheers.gif

[ 09-27-2003: Message edited by: piman ]</p>

09-30-2003, 03:09 AM
Thanks, guys, great input. I'll dive in the engine bay again, see what happens.