Screwy timing, or screwy timing light?

I have timing set at 10 degrees, but when I gun it, with the vacuum advance on, it jumps off the scale, up around 60+ degrees or so.

Is this ok, or is something screwy with my timing light?

It still jumps to 40-50 with vacuum off.

I read somewhere recently (recent car craft or hot rod?) that some guy was getting interference from other spark plug wires and making it read up in the 160 range. Just wondering if something like this is happening with me.

Not just now after the MSD, or with the new carb. It has always done this for me.

But it runs GREAT!

 

I'v seen a lot of balancers spun give bad readings. I would check the basic stuff as far as the wire deal but i bet that balancer is spun.

 

Balancer is a brand new Professional Products Powerforce balancer. Pretty top dollar, and I doubt it is out of whack. Especially since it is dialed in at zero top dead center.

It is also on at 10 degrees, it is only when the advances kick in that the readings go wacky.

 

Well, how much does your timing advance? 60? What distributor do you have?

 

Does the light have a advance knob? Set it to 50 or 60 and see what it reads.

 

some times the alt will mess with the pick up on the timeing light if its close. you can try puting the pick up on cylinder #6 and see if having it away from the alt helps. definitly get the pick up away from all other plug wires.
does it instantly jump to 60 degrees or does it ramp up as you bring up the rpms. i would raise the rpm slowly watching the advance curve that happens as you rev it up. you should be able to map it. write down the rpm and the related timing in 200 to 300 rpm incriments.

 

It jumps up pretty quick when I gun it to around 2000 rpm.

I will try the other plug wires and see if it still jumps.

 

I don't see a problem...yet.

 

What kind of distributor is it? I have seen several Dura-sparks come from a rebuild house with the vacuum advance turned all the way in. That will easily give you 60btdc of timing.
Some of the mid 70's large cars were also timing with gobs of vacuum advance to try and increase fuel economy.
Take an 1/8" I think, allen wrench and turn the vacuum advance out 3 or 4 turns and try it again.
clint

 

this is an O'Reilly replacement with vacuum advance. Maybe 5 years old. Then I have MSD 6A box, Pertronix.

I didn't know that the vacuum was adjustable...but now that you mention it, I seem to recall seeing people put allen wrenches in the vacuum tube.

So, the car runs fine on this advance. Should I even back it off?

I was more concerned that the light may be faulty.

 

thats something you should be able to fine tune on the dyno. im not sure how but there has to be a way to.

 

Is this one of the digital timing lights? If so, they won't work with an MSD. I had to buy an old cheapy to use on my racecar with the MSD parts.

 

my digital snap on timeing light does rean msd ignitions but i seriously doubt that he spent the big bucks on a snapon timeing light.

 

:16suspect I see what you did there...calling me cheap...

This is a decent timing light. But not a snapon. But it has a broken spring-loaded induction doohicky, and I have to tape it on to make it work, so I am in the market for another one.

Recommendations? What will work?

 

If it runs great then I would sure leave it alone. In the back of my mind I was thinking you were having problems with it when I answered. Think I got your post mixed up with another.
I have also heard of MSD ignition messing with timing lights.
See if you can borrow another light for a comparison.
clint