Can't set timing

[Dcfirebottle]

Hey there my fellow Chevy truck loving brothers and sisters.
Just put some new ignition parts on my 81 K10. Has a early 70's block with oval ports. Mild RV rebuild. Installed a new Accel Hei distributor with a Msd Hei style coil. 8.5 wires and Accel plugs at 35 or 40. Fired right up. Put a timing light on it and nothing, no flash. No problem, light was old. Run down to harbor freight buy a new cheapie light. Figure I rarely use it, so why another high dollar one. Bring it home attach to truck..nothing. No flash again. So I lift the hood on my 68 firebird. Almost the exact Hei ignition set up as the truck. Engine is a 400. What do you know, both lights work just fine. Now I have two lights that I'll rarely use. WTF. Anyone ever experience this phenomenon?
Now I know there are other ways to time it and I already have. Like I said runs great. I would still really like to be able to put a light on this truck once in awhile. Any ideas? All input is welcome and appreciated.

 

[Grit dog]

Dunno what to say unless #1 plug wire is dead. (A good running V8 runs pretty smooth on 7 cylinders with no load on the engine…)
Did you try another cylinder plug wire on the truck engine?

 

[SirRobyn0]

Dunno what to say unless #1 plug wire is dead. (A good running V8 runs pretty smooth on 7 cylinders with no load on the engine…)
Did you try another cylinder plug wire on the truck engine?

Agreed, also remember that the timing light needs power and ground, a surprisingly small amount of rust or dirty on the terminal bolts will prevent the light from working. Take the terminal bolts out and replace them or clean them up on a wire wheel and I'll bet both lights work on the truck.

A side from connection issues or a bad timing light I've never seen a timing light fail to flash.

 

[mtnmankev]

A side from connection issues or a bad timing light I've never seen a timing light fail to flash.

Originally, I was going to tell the OP to do an exorcism of the space aliens messing with him, but I won't type that.
I have enough trouble with them in the other end of the state.

Rob, you should use my light then.
And it's not an el-cheapo light, either.
Even with good solid clean connections, it flashes intermittently.
So, I leave it in the shed and time my engines by ear.

 

[AyWoSch Motors]

I'd say a bad connection at the battery. Clean up the terminals, hook it up and try it again. If still nothing, try the number 6 plug wire.

 

[SirRobyn0]

Originally, I was going to tell the OP to do an exorcism of the space aliens messing with him, but I won't type that.
I have enough trouble with them in the other end of the state.

Rob, you should use my light then.
And it's not an el-cheapo light, either.
Even with good solid clean connections, it flashes intermittently.
So, I leave it in the shed and time my engines by ear.

I'd think and I'm sure you'd agree, that your light likely has a problem. And of course I've had lights with issues. But in his case that's not the problem. Could be the space aliens but we won't talk about that.

Sometime remind me to tell you about the ghost at the shop and what he does.....