how big a spark?

vash · vash's Garage

ok, how big is the spark supposed to be when you pull a sparkplug, plug it back into the spark plug wire, ground it and have your poor girlfriend that you yank outta bed at 7:00am to crank the ignition, on a saturday supposed to be? up till now, i thought i did everything right. now on the first morning to drive with fellow pelicans my car takes a dump. cranks, fuel vapor wafting outta the pop off valve when i peeked, spark at coil, spark at plugs, (sorta anemic).
cliff

vash · vash's Garage

girlfriend is willing to drop me off at denny's. hope zoanas is good for that ride!

cliff

onewhippedpuppy · 02-28-2004, 08:14 AM

Just when you thought you had it licked....

. Did you ever replace your wires? If you have spark though, it should at least run, are you sure you're getting gas?

dhoward · dhoward's Garage

Should be blue with a crisp 'snap'. MSD makes more of a zzzzt!

JP911 · JP911's Garage

Cliff-
Turn the ignition to on and lift the throttle plate to check for fuel. I would guess that if there was spark, even a weak one, the car would at least stumble and then quit.

Early_S_Man · 02-28-2004, 10:05 AM

Cliff,

The spark should be blue-white and fat ...

I don't like to use a plug just pulled out of the engine as a test spark gap ... I use a new plug -- modified with a permanently-attached ground wire and clip! That way, conditions of a used plug -- fouling, worn electrodes, etc. ... don't vary the conditions and cause differences in the spark. I also use a new, specially-constructed ignition test lead without a resistor end ... plugged directly into the ignition coil, so conditions of the rotor, cap, and wires don't affect the test spark!

If you haven't already done so ... be sure to remove the CDI unit from the relay/fuse/regulator panel ... and clean the three connector male terminals and separate ground lugs, as well as the mating female Faston connectors. I usually run a separate braided ground strap from the corner mounting bolt of the CDI unit to the forward bare, cleaned, ground location at the fender panel. IIRC ... the relay panel has three or four mounting bolts, but only one has the bare spot for grounding! Clean and apply silicone grease for future corrosion protection.

onewhippedpuppy · 02-28-2004, 11:18 AM

I love reading Warren's posts, I always come up with something else I need to do to mine. Cleaning CD connections/ adding ground is now on my list, thanks Warren.

vash · vash's Garage

ok, i am getting over the seasickness feeling of being in some very fast 911's on some very fast winding roads! tell you the truth, i am sorta glad my car didnt start

these guys are great! jumpsuit on, i am going in! thanks guys. pictures of the run later.

onewhippedpuppy · 02-28-2004, 03:12 PM

Lucky ba$tard, I spent all day stripping a hardwood floor. Gotta keep the wife happy, or at least try.

Bigtoe · Bigtoe's Garage

Cliff,
While I was performing the first tune-up on my '76 2.7, moving wire harness bundles and adding Magnacors, I unknowingly cracked the brittle trigger wire that comes off the dist. The wire grounded out against the shielding and the trigger signal was lost. Take a minute to ensure that pin C of the CDI harness plug does not show continuity to ground with the terminal disconnected from the dist.

Hope this helps.

Por_sha911 · Por_sha911's Garage

Warren, awesome idea. Can we get a picture of this test plug of yours?

Doug Zielke · 02-28-2004, 07:03 PM

Don't know if Warren's ignition/spark tester is similar to this....

From KD Tools. Less than $10. I keep one in the 'Bombers tool roll.

vash · vash's Garage

thanks guys. trouble is this situation is intermittent. i got it to start, well it just started yesterday afternoon. i did nothing. now this morning, my crazy car is at it again. i went jumped through the hoops that warren suggested, no go. i missed big toes. i will look for spark and try toe's suggestion.

warren, the one panel bolt that is groundable had a ground wire attached to it. i moved that ground in front of the panel, because installation was easier. and i attached an extra ground strap to the panel and the chassis of the CDI box. still no go. i will go and buy a spark plug like the one illustrated above by doug, because it looks like a good thing. for the record, the panel so far has been the most painfull thing i have done. i gave blood for that one. to delicate a job for gloves, and everything is sharp as razors!

my car is schizophrenic! i think bigtoe may be onto something, because i moved things around to install the alternator.