[MaineHandyman]

I have a sb 350 1978 hei distributor, when i hook up my timming light it is not costant the light flashes out of sequense, it is 100% on the #1 wire and i have done it before but what would make the light flash irratic? i tried it on my car and it worked fine so its not the light, any thoughts?
thanks

 

[XNTRCI-T]

Do you have a multi-spark ignition box?

 

[jarrettandroski]

my car does the same thing sometimes its wierd sometimes it doesnt work at all sometimes its all eratic and sometimes it works flawlessy and other timing lights do the same thing on my car its strange the car runs fine though

 

[MaineHandyman]

no multispark box, just wondering if the new hei distributor can cause that, or if my timing is jumping all over somehow?

 

[OLNOLAN]

Probably Misfire

Hey Handyman, If I'm reading this correctly, if the timing light flashes randomly or off sequence on only # 1 wire then you've got a bad plug or wire. I use a timing light as a quick troubleshooting tool on an engine with a bad miss. I've shown people this before and they had never heard of such. Power your timing light up and clip on to one plug wire at a time. I shine the light in the palm of my hand and look at the flash. Good cylinders will flash constant sequence, cylinders with a misfire will flash out of sequence. Like on-on-on-on-on-OFF-OFF-on-on-on-on-OFF-on-on-on-on. You can also use a Dwell-Tachometer the same way. Clip on to one wire at a time and the cylinder with a miss will read lower RPM than the good cylinders. Let' call it my POORMAN'S OSCILLISCOPE. olnolan

 

[75gmck25]

I've had that problem once or twice, and I sometimes switched to using the #6 wire instead. It will give the same results, and on my engine its a little easier to reach the wire (AC compressor is above #1).

Bruce

 

[MaineHandyman]

I actually tryed it on all wires and it does the same, now my truck is running to hot and rough, where can i go to get instructions on timing it as close to perfect as i can? thanks for the info guys...

 

[OLNOLAN]

Dist Cap/rotor

I actually tryed it on all wires and it does the same, now my truck is running to hot and rough, where can i go to get instructions on timing it as close to perfect as i can? thanks for the info guys...

The only time I ever had one blink erratically on all the wires was caused by a bad rotor cap(actually the blade was bent flat out of the box,bent it back up to touch the distributor cap button). You may want to check dist cap,rotor. Hope this helps.olnolan