The problem is that, if i connect my timing-light, it doesnt get a good signal from the plug-wire.

All the other wires are working good with the timing light, i took out the sparkplug and connected it to the wire and hold the sparkplug to the body of the car.
It fires perfectly.

So, if i put the sparkplug back into the engine and connect the timing-light again, its doesnt work, just every now and then it gives a quick flash.

shaking and pulling the sparkplug makes no difference.

-Its absolutely sure its not the timing-light itself, its working perfectly with the
other 7 plugs.
-the sparkplug is good, it sparks perfectly when out of the engine and connected
-the sparkplug wire is good, i used 2 wires to check.
-distributorcap is new and good.

So, every part is okay and working, but ones the sparkplug is installed in the head, my timinglight does doing weird things.

Is it a ground problem? the sparkplug isnt making good contact with the head, maybe?
I did spraypaint the engine, but if the sparkplug is screwed in it should scrape of any paint in the threads.

I put a wire to the outside metal of the sparkplug and connected it with the body, but maybe its to little to make a good ground connection.


Weird isnt it...?

Yes, that appears to be a weird one for sure!:yes:....Try clamping the inductive pick up clamp to the #1 plug wire about 6" from the cylinder head....I still believe it's a loose wire connection within the timing light as I had this problem once and I repaired the wire coming out of the timing light.

the timinglight isnt the problem, it's an expensive 1, and it works perfect on all the other 7 plugwires.

But ill try moving it 6" from the cylinderhead.
thanks for your reply.

It is possible for something to be wrong with that plug. I'd change plugs. I have heard of problems with the cylinder heads not being properly grounded, that is why GM provided ground leads from the firewall to a valve cover bolt on each side.
Ground your timing light to the engine, not the body, the battery cable must connect to the engine block or on a 69, the alternator bracket.
David

It's not firing the plug, most likely due to paint but I'm with David, either change it or swap it and see if the problem follows the plug. Just an FYI, the Majority of the ground and heat sink is achieved through the gasket area or taper whichever yours has, not the threads. After a plug has been in operation awhile residue develops on the threads. We change gaskets and clean seating areas every time we pull our $100 apiece plugs.

If you have a VOM, put it on the plug on resistance scale, from center electrode to where the plug wire attaches. Compare the reading to another plug that's firing OK. Depending on what style plug you have the reading should be anywhere from about 5 ohms up to about 10K ohms. Not real familiar with the readings on resistor style plugs. Our $100 ones are usually dead nuts 1k. The AR-50's I use in my car are way low resistance and usually under 100 ohms.

Meanwhile you can set timing with #6 cylinder if you have a 18436572 firing order chevy. I use #15 on V-16's, It's about 8' closer to the timing marks on the flywheel:D.

i will swap 2 plugs and see if it makes a change.

Bad plug. I have seen this many times.

Yes i would say it is the plug. Some times a bad plug will fire in the open but will not fire under compression. I have personally seen this on my sister's car [chevy citation] about 10 years ago this problem drove me nuts for a a few days

i agree with the bad plug guys..ive had this happen to me as well....witht he possibillity of bad groundign on that plug for a close second...haha:)

ive had several accel plug sets,and i must say they fail pretty fast!

i once have had my first set of Accels, that after 300 miles, 4 of them failed!

Which brand are you guys using?
i know it depends on your engine for what type (cold/hot) but i only want to know what Brand youre using.

Accel is over for me.

A fouled plug will do exactly that... fires OK at normal atmospheric pressure, but won't fire under compression stroke pressure. Two things you can try:
1) run a smaller plug gap (.030?)
2) run a hotter plug

I like NGK plugs

NGK for me as well. AC plugs fail too often.

Time it off of the NO. 6 plug

Jack's right. What did you do before the problem occurred? If you pulled the distributor you could be 180 out. Does the engine run? If so, you ain't out but if engine won't start. maybe???

It sounds like a shorted plug or fouled plug. That condition would lower the firing voltage of the plug, and that would mean less voltage to sense. Unplugging the wire from the plug would greatly increase firing voltage and give a better signal to the light.
David

engiine starts and run, it idles like crap but i quess its the 106lsa.

terminal 1 in your distributer is either cracked, bent or loose, most of the acr gap jump is in the distributer (rotor to #1 wiper, to terminal pin, to wire), causing weak spark at the plug. A worn rotor may be contributing to the issue as well.

Guys as far as plug wires go, different subject. I bought that kool MSD plug wire tool, pliers, make my own MSD wires, way cheaper and you can make exact lengh wires in a snap, first time every time. Just thought i would throw that in, only way to spark....