setting up SU H6 Carbs and setting up teh choke

[Farid]

Hello all!

I have two important questions which I would appreciate your input fo.

 

Question 1:

I have refurbished my carb (changed all the corck and brass washers, etc), and centred the jet. After tuning both carbs with the appropriate vacuum tool, I have been trying to set the carbs. As the instruction says, we should lift the piston by a very little amount (1/16") to see whether as a result the motor runs faster or slower, so to adjust the richness or leanness of the cars. However, in my case, I have to literary lift the pistons (same for both carbs) at least 1/2"-3/4” to see any difference in tone.

Any idea why this happens, or whether there should be a concern?

 

Question 2:

Although, seemingly the jets are centred (since when I drop the piston, I hear the “click”, when I pull the choke cable and then release it, the jet seats do not go back up all the way to where they originally were. Of course, when I try the individual carb on the bench, the choke seems to function OK and not binding, it is just after installation that they act up.

I even put a stiffer spring to the one on right (which sticks a bit more), but once the seat is pulled down, it does not go back to its original place.

Any trick?!

Cheers

Farid

[Icarus60]

Hello Farid

 

I think you need to fix issue 2 first. Did you soak the cork seals until nice and compliant? You must get both jets to slide up and down without undue binding. The root of the problem seems to be too much friction between the jets and the cork glands. This should be fixed first and fitting a stronger return spring is not really correcting the root cause of the problem. When this is fixed, set both jets down by about 0.038 inch and and check that the pistons drop with the click again and recentralise as necessary. Rebalance the carbs and connect up the two spindles ensuring that the engine stays in balance when the throttle is off the idle stop. You may have to adjust the mixture very slightly but if you set up as described you should have a very close stating point.

 

Hope this is useful

 

Regards

 

Gerry

[Farid]

Dear Gerry:

I had of course oiled the cork washers. Not only did I oil them, I let them sit in W90 weight oil for over a night before assembly.

The only think I may conclude is that the kit I got (for the washers) was an inferior kit, such that the cocks are probably too tight?

The reason for the above statement is that the sealing gaskets for the fuel bowl next to carbd did not fit well either at the time, and I had to do a significant amount of careful grinding to have them fit to the rim.

Regards,

Farid