The thing I like about SU carbs is that you can tinker with them.

The thing I don't like about SU carbs is that you have to tinker

with them.

I replaced the stromburgs on my 164 with a pair of rebuilt SU HS6

carbs. The replacement went kind of okay (well, I'm an idiot so

that was working against me) and the car pretty much runs okay

now except for a couple problems.

Choke -- the car currently has only one cable that goes from the

choke to the carbs, and I need two. I can fix that but it will

take a visit to a bicycle store. No big deal for now, I just

tie the choke levers up and start the car with the hood open.

Ugly but it gets me to the bicycle store...

Another problem is that I'm having a hard time adjusting the

mixture. If I remember correctly (it's been months since I did

anything with the SUs) if you raise the piston a little bit and

the idle speeds up, the mixture is lean, and if it slows down

the mixture is rich. Also the idle seems kind of high but if

I lower it beyond a subtle point the car just dies every time.

As it is, it always makes the idle lower, but if I adjust the

mixture past a certain point it just dies.

Which leads me to the last problem -- the car runs okay except

sometimes at mid throttle under load (hills) the car will start

to buck. I suspect that I don't have the carbs balanced quite

right (mixture wise) but I can't be sure since I just did it by

eyeball since I can't trust the other factoid I seem to remember

about SUs. The unisyn tells me they have the same idle, but

big deal -- I'm not using the idle.

Oh, this car has a coil with a resistor in front of it and it

says that it wants 9v. My 144 does not have this sort of coil.

Should I try to find a normal coil for a 140 / 160 in a junk

yard and replace this one?

Suggestions?

chris

Chris,

Assuming your car has a standard points-type distributor, not electronic, I'd stick with the resistor coil. I've tried substituting a standard 12 volt coil and it made not a jot of difference. The 164 uses a resistor to extend the life of the ignition points, which make contact more often in a six than in a four cylinder engine.

Hey Chris!

Been there. I noted a couple things in your comments, one

not seen. Did you take out the secondary butterflies in the

manifold or are they still there? If they are, do the carbs

have the arms to open them? If not, you have to take the secondary

butterflies out or you only get about 1/3 throttle.

When you lift a piston and it speeds up, your mixture is RICH.

If it slows down it is lean. If your throttle shafts are loose

in the carb body, allowing air leakage at idle, all bets are off

and you cannot set mixture on the basis of idle behavior.

IPD is now selling Gunson's "Colortune" device, which I heartily

recommend. I use two of them, one in #2 and one in #5 so I can

adjust both carbs at the same time. After getting good initial

settings you can check manifold effects by comparing 2 with

1 and 3; 5 with 4 and 6. Because of manifold design, it will

never be perfect but you can average out pretty good.

Pete is right, choking one carb is sufficient. don't worry

about stringing more cables.

Choke -- the car currently has only one cable that goes from the

> choke to the carbs, and I need two. I can fix that but it will

Strangely it will start quite happily with just one choke connected, as per the original stromberg setup

If I remember correctly (it's been months since I did

> anything with the SUs) if you raise the piston a little bit and

> the idle speeds up, the mixture is lean, and if it slows down

> the mixture is rich.

You need to first balance the carbs and get the timing right. You will need to use a fairly rich needle, KD at least???

Then set the basic setting on the carb, each needle down 6 flats. I assume you have removed or jammed the secondary flaps open?

Richen the carbs equally by backing off each jet equally until you have the fastest idle speed, then lean off two flats.

Check the two carbs are still pulling equal amounts of air, if necessary re adjust the idle, equally on each carb

Lift each piston in turn with the pin on the body. If the engine speeds up lean off the other carb a flat, iff the idle drops right off richen up the other carb a flat. Neither carb should need the jet adjusting differently from the other by 3 or 4 flats.

The carbs are right when you lift the pin and the engine nte picks up very slightly and then drops the idle by 300 revs or so.

Before you start make sure you have a proper float level. If the level is too high the petrol will syphon into the carb rather than the vacuum of the engine pulling it out of the jet and you'll never get it set right. Equally if the ignition timing is way out settings based on idle will be spurious.

Regards