I have an SBC with standard ignition. the car started running poorly and fouled the plugs. i replaced the cap, rotor. points and condenser. i also replaced the coil a few minutes ago. i ohmed out the wire from the coil to the points. with the ignition on i get 12 volts to the positive side of the coil. i took out one of the plugs and held it against the header while my wife cranked the engine, she wouldnt hold the end of the spark plug wire, and i am not getting any spark. i am out of know how. any ideas?
First, why did it foul the plugs?? did you re-check the gap on your points? did you check your coil? just 'cuz its new, don't mean its good!! especially if you bought it from one of the big "chains" Auto Zone, O'Reillys, etc. just kickin' some ideas out there, personally, I'd run an HEI. don't hafta worry about points, etc. Vance
i am assuming too much gas from me pumping the pedal fouled the plugs. i cleaned them and put them back in
something else to check, is the contact on the rotor making contact with the cap? as for checking the coil, I don't remember how to check them, but you should be able to do it with a volt meter, I would think. hopefully somebody else with more smarts than I, will chime in Vance
12 volts goes to the positive side of the coil and the negative terminal side of the coil goes to the points. Double check that. It'll run - but not good- if you've got them switched. Turn the key on and 'break' the points with a screwdriver. You ought to get a spark there. If you have 12 volts at the positive side of the coil and you have no spark at the points then its either the coil, the points or condensor, broken wire/open circuit.......or installation error. If you have spark at the points then its the cap, rotor, wires or plugs. -Bigchief.
COIL - If you have a multi-meter, turn the meter to resistance or an ohm reading. Disconnect the coil... With one lead on the negative terminal and the other meter lead on the positive terminal, the coil should read a high resistance, NOT ZERO. If the coil reads 0 ohms, then the coil is shorted out...
Standard point type ignitions use reduced voltage going to the coil when the engine is running through a resistor from the ignition switch. In the case of most Chevy's it's a resistance wire from the ignition switch to the coil. However, during start up on a Chevy a contact on the starter solenoid sends full battery voltage to the coil to give better spark during cranking. Once the ignition switch comes off start a reduced voltage is sent to the coil. Full battery voltage will cause burnt points, a bad condenser, and possible coil damage. Found this out a long time ago, the hard way! Also make sure everything had a good ground! Especially engine and body to battery!
I had a similar problem with my sbc. I was always changing the plugs because they would foul. I put in a unilight set up inside the stock distribitor and put a new high output coil and 3 years of city driving hasn't fouled a plug. Just put the pertronix set up in my flathead and installed a flamethrower coil. It has worked wonders.
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