hs2 problem

[SilentUnicorn]

Hi folks, my neighbors car( say Hello to Lance) is being a little finicky. here is a brief description,

the car is a 1275 1974, hs-2 carbs. car bucks and hesitates on acceleration. problem appears to be in the front carb, seems to be a lot of fuel on the bridge of the carb, more so than on the back. if the front and only the front is sprayed with some carb cleaner, the problem goes away for a bit. possible sticking needle?? points and plugs and wires are new and clean. electical is all clean and tight.

any and all ideas welcome

thanx
mark /ubbthreads/images/graemlins/driving.gif

 

[trrdster2000]

Mark, couple of things you might try. The needle and seat could be bad and flooding it out, check the plugs and see if those two are real black or the other thing is the secondary butterfly spring has broken or is weak. Pop the piston up and you should see a small peice sticking out of the butterfly, push it with your finger or small screwdriver, it should only wiggle a bit and have a light tension on it, not many go bad but when they do it's the last thing you look for. Wayne

 

[spritenut]

Like Wayne said about the poppet valve on the throttle plate.
They do go bad if the car ever back fired thru the carb.
The exhaust heat will kill the spring on the poppet.
A common fix is to remove the throttle plate, snip off the poppet, and solder up the holes on the plate. File the solder smooth and you will never have the problem again.

Frank

 

[aeronca65t]

I agree with the guys above.
Also, try swapping the float needle and seat to the back carb. If the problem moves to the back cylinders, you've found your problem.
Be sure that the float level is set correctly. An 1/8" drill bit should just pass between the float and chamber lid when the float is topped out.
A useful way to see if the carb has a decent mixture level is to remove the air filters and let the car idle. Use a small screwdriver to lift the piston about 1/8". If the engine speed stays about the same, things are OK. If the RPM goes up, it's rich. If RPM drops, it's lean. (some SU carbs have a little built-in"button" to lift the piston for this test).
And be sure your intake manifold bolts are tight (a common problem) ....if in doubt, spray carb cleaner or WD-40 around the manifold gasket while the thing is idling (if it's leaking, you'll hear the RPMs change).

 

[SilentUnicorn]

thanx,

would the float level being high be the reason for seeing more fuel spray on the bridge of the carb?


mark

 

[aeronca65t]

would the float level being high be the reason for seeing more fuel spray on the bridge of the carb?......

Yes, absolutely.

 

[SilentUnicorn]

any suggestions on how or what to use for shims to adjust the float?

mark

 

[aeronca65t]

On some HS2s, there is a metal tang that you can bend to make this adjustment (I think, the brass floats).
On others, you unscrew the float needle/seat assembly and put a shim under it. For shims, I'd probably use thin brass sheet (cut with a scizzors) to make these "washers". In a pinch, I'd cut up an aluminum soda can and use that.