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Carb & Needle ZS CD carb

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wbdvt

Senior Member
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Hello,

When I bought this car, 1980 Spitfire, in the fall the air piston in the carb was stuck. I rebuilt the carb and installed a new needle. There was no brass number tag on the carb, so I went by the table in Moss Motors catalog and ordered a 45N needle. When I took the carb apart the needle was a 45L, which would be for a 1977 Cal car. I doubt that the car is from California and ended up in VT.

I am still running rich and have turned the needle as far left as it can go. Since the exhaust system has been replaced with what looks like a performance free flow exhaust system, could that have necessitated a needle change to get the mixture leaner? I am using a Colortune to judge the mixture.

Thanks all in advance for reading and replying.
 
Don't be surprised if it is a Cali car. The parts car I have the motor and trans out of is a Cali car and I am in PA.

BTW what is the motor # stamped on the block?

Should start with FM...
 
Hi Don,

I just looked at a chart of engine block codes and it appears that the "C" in the suffix indicates that at least the engine was from a Cal car. But with all the mods done (exhaust system, EGR gone, etc) would this still need a 45L needle? I have no problem re-installing the needle and seeing if I can lean out the mixture more.
 
Thats why I asked...Don't like to assume...

Its worth a try.... How was the float level when you rebuilt the carb. fuel too high in the bowl might be a problem.

Did you change anything on the intake side. i.e. unsing a high flow air filter?

I take it you already checked the valve lash, timing and plugs, good spark to the plugs.


My spit is a little rich in the exhaust but the plugs look good at Idle so I haven't bothered trying to correct it.
 
Hi Don,

It came with a high flow air filter. The float height was okay and I did check the valve lash. The spark originally looked weak and I replaced the coil and the spark looked a lot better.

Thanks
Barry
 
Barry,

As I have been learning about these carbs, the high flow filters can change the air flow enought to need a different needle.

hopefully someone will pop in that has already had this prob..

I'll be fightin this fight when I get the dual SU carbs rebuilt.
 
Don,

Well, the way I see it, if it is the original carb on this California engine, I should go back to the 45L needle and see how much that allows me to lean out the mixture.

I also have a misfire on all four cylinders but that could be due to the soot build up on the plugs. I figure I'll get the mixture correct, put new plugs in and see if I get the misfiring then. Since this has a Allison XR-700 electronic ignition which looks original as it has a RCA canned transistor mounted to a large heat sink, I wonder if it is at it's end of life.
 
Is there a chance you are getting unmetered fuel from the choke mechanism some how? Common problem on the TR7 and TR8 zeniths.
 
tr8todd,
Good question as the choke is funky. It is a conversion to a manual choke and seems to work only in full open position, try to close it and cuts out engine.
 
That's because you have the needles fully adjusted down. Sounds like your running at idle on choke delivered fuel only.
 
Thanks, good observation. I will change the needle back to the 45L and see what changes that makes. Should have everything straightened out by the time VT driving season arrives!
 
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