QuestionQUESTION: For 25 years, I've been saving my 76 spitfire for my son, the car is in emaculate shape (rarely driven). This year I removed it from storage (once per year for two weeks) and it was running rough for the first time. The exaust was blowing lots of black smoke. I change the plugs and it ran very good for about 2 hours (still blowing quite abit of black smoke), then it started running rough again. The new plugs were very carboned up after only 2 hours. My neighbor said it looks as though I'm running way too rich. I'm not a car person and there's no one around this area that works on spitfires. Any suggestions on how to adjust the carb (if thats the problem) would be greatly appreciated. Thank you, Randy Lachine
ANSWER: Hi Randy,
Black smoke is a sure indication of excess fuel mixture. It is not likely that the mixture adjustment could get that far off just setting. So you must look for other causes. The first would be the choke system which is a high failure rate item anyway. This is a US version with a single Stromberg carburetor on it, correct? First you need to remove the top cover to see that the diaphragm is in good shape and if it is ok then replace it and remove the three small screws around the edge of the choke coolant assembly on the left side of the carburetor and lift the assembly away. (Don't remove the center bolt nor the two coolant lines.)
You will now see a small lever sticking out of the side of the assembly still on the carb. You can move that lever back and forth. This is the choke itself so now you can operate it manually. Start the engine and move the lever by hand and you will quickly see which direction is "Off" choke. I think clockwise is "Off" but don't count on my memory being correct there. If the small lever does not move then corrosion and dried up fuel is probably the cause and you must free it up either by moving the lever back and forth or remove the rest of the assembly and clean it out.
Let me know,
Howard
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QUESTION: Howard, thanks very much for the information. I removed the top of the carburator and inspected the diaphram. It did not appear to be damaged but I will replace it. I removed the linkage for the choke and noticed a round plate with a slot inside that appears to line up with a matching slot on the carburator. There did not appear to be a lever inside the hole on the carburator. There was a pin protuding through the round disk with the slot. I pushed on the disk and it moves in and out over the pin (very small movement in and out. After looking everything over, I did find a hole in a hose leading to the carburator from a cansister in front of the radiator. I'm not sure what this hose does but could this be causing me problems (I will replace the hose). One other question, what is the oil material inside the cap of the carburator that goes down inside a tube thats inside the carburator? I'm assuming that I will need to replace this oil material.
Thanks Howard,
Randy
AnswerRandy, the pin sticking out of the slot in the plate is the choke control and the pin moves the length of the slot not in/out.
The hose to the canister is probably a vent hose.
The oil in the top of the carb is just engine oil and is a shock absorber so the piston don't move to quickly or pulse up and down at idle. The reason they don't want the piston to move to quickly is that it acts like a accelerator pump in a conventional carb by speeding up the air across the jet on a quick throttle opening.
Some people use automatic trans oil but I found that engine oil works best.
Howard
