QuestionQUESTION: hello, I am having a problem with starting my 1976 spitfire. Dont know much about the carbs, but they are duals. It just cranks, and fuel overflows at the first can? Sorry I dont know the correct terminology, is it a float canister? very little fuel gets past that to the second one. i got fire a couple of times, so i know the ignition works. I have had it about a week, it has been sitting about a year or two. Any basic help would be greatly appreciated. I am trying to get it running for my mother in my spare time, please help!!
ANSWER: Hi Zach,
If you have dual carbs, they are SUs and if the front one is flooding, you need to correct that before any further attempts to start the engine. The top of the float chamber you referred to as the "first can" has three screws holding the top on. It will have a fuel line on it and one other tube which is a vent tube. You can remove the fuel line and any hose on the vent tube (if it has a hose on it) Then remove the three screws and lift the top off of the float chamber. The float itself will be attached to the top you remove. Look at the float and you will see that it pivots on a pin and must be free moving. Pull the pin out to remove the float and be careful to catch the float needle that the float arm keeps in. Check the float so it is not full of fuel. Look at the end point of the float needle to see if it is dirty or worn a grove around it. Clean all the parts and reinstall them and hold the top up so the surface is 90 deg to the ground and so the float is hanging down. At that position you should be able to just slide a flat piece of anything that is 1/8 inch thick in between the float arm and the float top. That is the setting of the float. If it is not 1/8 in clearance you must bend the float arm until you have 1/8 inch clearance. then reinstall the top and check the rear float too as it may not be letting any fuel in.
You need to purchase a manual for this car. They are fun cars to have and drive but do require a lot of maintenance to keep going.
Let me know.
Howard
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QUESTION: ok, sorry to take your time, but can you clarify a few things for me? you say hold it 90 deg to the ground and check clearance btwn float top and float arm. do you mean horizontal? I dont understand because the float arm is connected to the float top. if i hold the float upside down should the float be horizontal? should the needle fall out when i turn it upside down? because it does not unless i give it a small shake. you said one tube should be a vent tube and the other a fuel line. well, maybe its plumbed wrong, but it is connected in series with the second bowl. primary fuel comes in the first bowl, goes out and into the second bowl. is that right or sould it be a dual feed like a holley? sorry to compare, but this is new to me.Thank you very much for your help until i can get a manual.
ANSWER: Hold the lid 90 deg to the way it sits on the car so that the float is hanging down. in that position the float in hanging down and against the needle holding the needle into it's seat lightly. The only reason you don't just hold the lid upside down to check it is because the original needles had a spring loaded pin in the end of the float needle and that would be depressed if you held the lid upside down.
Even though you have two fuel lines on the front lid the fuel has a bypass in the lid to feed the other line going to the second carb. The third tube in the lid is just a vent.
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QUESTION: Hi again, thanks for your help with my initial problems. I do have SU carbs, I replaced the needle and seats and set the float levels. My problem now is it starts, and idle like its only running on 2 cylinders and barely runs, but when i bring up the rpms, the engine smooths out. Any suggestions where to start? The previous owner seems to think a cracked head, he even gave me another head, but I am not so sure because it smooths out when i rev it up, and the radiator level is not low. thanks!
AnswerYou can't make a determination that it might have a cracked head form the fact that it seems to run on 2 cylinders at idle. Several tests are needed.
First set the valve clearance
Then do a compression test. (Dry & Wet test)
Next with it idling short out each spark plug to see which cylinders are not pulling their load at idle.
Then try to adjust the idle stop screw of the carb that feeds the dead cylinders to see if you can pick them up at idle.
Let me know,
Howard
