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  • Klayfish

    May 11, 2011 1:07 p.m. Klayfish Reader

    Prior to taking my timing belt back off and trying to change the cam seals, I recently bolted the intake manifold and carb onto my Spider. Put a few drops of fuel in the carb to see if it would fire up...not literally ... It's been in a slumber for years, would be cool to hear it run.

    It cranked over very nicely, but didn't start. My first thought was to check for spark, as it never sounded like it was about to catch, just plain old cranking.

    Are those spark plug testers that the big parts stores sell for $8 decent, or should I try it myself? I've never checked anything for spark before and don't want to get a nice shock. So if I'm doing it myself, what's the safest way?

  • tuna55

    May 11, 2011 1:10 p.m. tuna55 SuperDork

    Have someone crank it while you ground it on the engine block and watch it. That or just grab it, if it hurts, it's working. It doesn't hurt that badly. Seriously.

  • May 11, 2011 1:28 p.m. triumph5 Dork

    Have friend hold on to spark plug lead turn engine over. If yelling occurs, you got spark; no yelling, coil or wring to it is dead. Tuna's right, it doesn't hurt that bad, and is a RIGHT OF PASSAGE that we've all gone through. If it really numbs the arm, that's GREAT.

    place spark plug on block, with electrode in shade, crank engine over, if you see a spark, well, ignition works, no spark is no spark. Make sure the plug is touching a clean, well grounded part of the block.

  • 914Driver

    May 11, 2011 1:37 p.m. 914Driver SuperDork

    Put the plug in the rubber boot and rest the threaded part on something metal, crank. It should light up. Please don't give your friends or neighbors a heart attack.

  • N Sperlo

    May 11, 2011 1:48 p.m. N Sperlo Reader

    Just pull it out and put your tongue on it...

    Wait what were we talking about?

    But really, don't do that. I've heard of people sprinkleing a little water on. Personally, I've never tried that. I've got no problem seeing the spark when grounding as Tuna said.

  • foxtrapper

    May 11, 2011 1:57 p.m. foxtrapper SuperDork

    Take the spark plugs out, plug them in, lay them on the engine.

    Turn key. Watch for sparks in the plugs.

  • Graefin10

    May 11, 2011 2:50 p.m. Graefin10 Reader

    I think Harbor Freight has a spark tester that's a copy of an old KD unit. It does work and is a quick and safe way to check for spark. I recommend also getting an insulated gripper for ignition wire removal while you're there.

    I've seen many old school mechanics use the hold it and crank it method. With modern ignition systems I surely don't recommend it though. In the late 70s I worked at a JRT dealership and we got a bulletin advising us to be very careful with the latest Jaguar ingnition system because an unfortunate mechaic was electrocuted with one. Not long after that I pulled a job ticket for a dead MGB. I found it on the new car lot parked in a large puddle of water. To save time most of the JRT guys would always take the tools known to allow us to test a few things so hopefully we could start the car and drive it into the shop instead of having to get the push cart and a helper. As it turned out, the car had an aftermarket ingition system and some sort of aftermarket coil. I turned on the ignition and reached in to pull the coil wire and my hand brushed against a bare wire coming from the new module. We never figured out what happened but the thing lit me up. Even though the engine wasn't running, some how it began disscharging an ignition spark through the small wire coming from the module and I couldn't move to get away from it. As I fell backwards my hand pulled away from the wire. I caught myself before I hit the ground but I think my heart was still stopped. Shortly after I began to have palpitations and got so dizzy I almost did hit the ground. I know, this story may have a funny edge to it but it scared the crap out of me.

    For a humorous ign. spark story, in one of my first auto shop endeavors, my partner's dad had a serious drinking problem. I was tuning up a Ford one day and he stopped by quite inebriated. He came up to watch what I was doing and the engine was running so he reached out and lay his bare hand on the the distributor cap. I turned and asked wtf are you doing . . . when I did I couldn't miss that he had his fly open and was holding his tender parts to the chrome bumper. He looked up and said, "it'll put lead in your pencil". I didn't know whether to laugh or cry.

  • May 11, 2011 2:57 p.m. triumph5 Dork

    Sounds like you got zapped by an early CD ignition system. Yes, an aftermarket system can really zap you. The spitfire's got one I would NOT want to be zapped with.

    I was working on a guy's boat, PITA owner hanging around. I gave himm the new magneto to hold---complete with lead. Yup, three minutes later after he turned it over, he "had other things to do." Stll remember the yell... . To be safe, go with the plugs resting on the block test.

  • benzbaron

    May 11, 2011 3:48 p.m. benzbaron Dork

    Guy on the mercedes forum went to check for spark on his 560sl by pulling a plug and grounding to the engine. I guess the spark took the path of least resistance and fried the electronic ignition module which is a very expensive part.

  • Graefin10

    May 11, 2011 3:58 p.m. Graefin10 Reader

    benzbaron wrote:

    Guy on the mercedes forum went to check for spark on his 560sl by pulling a plug and grounding to the engine. I guess the spark took the path of least resistance and fried the electronic ignition module which is a very expensive part.

    That's why using a spark tester that connects from the spark plug or coil wire to the spark plug or dist. cap is the best way to do it.

  • turboHLS30

    May 11, 2011 4:03 p.m. turboHLS30 Reader

    Put a phillips head screw driver in the end of the spark plug wire and lay it on the valve cover, have someone turn it over and if you see the spark jumping from the screwdriver to the valve cover you have spark, if not, well you understand

  • Toyman01

    May 11, 2011 4:24 p.m. Toyman01 SuperDork

    tuna55 wrote:

    Have someone crank it while you ground it on the engine block and watch it. That or just grab it, if it hurts, it's working. It doesn't hurt that badly. Seriously.

    I shut down a 5hp Briggs, running WOT, by grounding the plug into my bicep, while standing in waist deep water, leaning against an aluminum boat. I was trying to keep the pump from falling off the seat and into the bottom of the swamped boat. I beg to differ, it hurts like hell.

    The best spark tester I've ever used is a plug.

    Also a few drops of fuel isn't going to fire a engine that is cold and has been sitting for any period of time. A shot glass full might, but not a few drops.

  • May 11, 2011 4:31 p.m. Don49 Reader

    I can't believe no one has suggested hooking up a timing light.It's safe easy and accurate. It doesn't matter what plug wire you put it on. If it flashes you have spark.

 
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