Is my timing tab off?

[SUX2BU99]

My truck runs alright but it can run better. I bought a timing light to see where my timing is at. I put an MSD timing tape on, and made sure it was on correctly, put white out in the groove in my 6.75" balancer and marked the 15 and 38 degree marks because the timing tab I have goes right to the edge of my balancer. I dont' understand that because it then makes it very difficult to read the timing tape!

Anyway, upon using my timing light I find that at the 0 degree mark on the timing tab it shows up at my 38 degree mark on the balancer! That doesn't make any sense so I'm wondering if I have the wrong tab. It's the same I bought the truck with 7 years ago (350 was redone in 1999). Had the cam and heads redone in 2008 and my mechanic mentioned some trouble with the timing but said he got it figured out. I'm wondering what he meant by that now. My truck runs okay but I think there is more power in it. It surges a little at low-RPM cruise, doesn't ping at all even on 87 octane but nose dives some at more than 1/2 throttle then recovers. It's run a best of 14.87.

This is the tab I have:
That's not my motor but it's same tab (the bright, large one)

Motor specs:
60-over 350, Dart Iron Eagle S/S heads (165cc, 1.94/1.50), headers, Eddy 650 carb, alum. dual plane intake, Mallory Unilite HEI, flat-tops, Weiand water pump, stock (as far as I can tell) balancer. The previous heads that were on it were from 1972 so I'm guessing that's the block's date as well.

I know GM used different timing tabs but at what orientation? 12:00, 2:00 and ?

[HAULIN IT]

Sux, My advice would be to get a piston stop to verify the TRUE TDC of the engine. You can either use the timing tape you have (assuming it is the correct one for your balancer) or a degree wheel. What you want to do is determine if the timing mark on the balancer is correct to go from. Use a piece of wire & make a pointer aiming roughly in the area of the TDC mark. You will install the stop, roll the engine over by hand until it stops...write down the number, turn the engine the opposite way until it stops again...write that number down, count the number of degrees. Half way between the Two is true TDC. Remove the stop, rotate the engine to this spot. It may take a couple times to get the pointer to work out. If your way off on the pointer, bend it some & repeat. Re-install the stop & repeat rolling the engine each way to verify that the balancer mark is now exactly half of your Two readings. If it isn't, your balancer mark is off. It does match, you need to find/make a pointer in this location. Do this & report back. Hope this makes sense, it's probably easier to do it than explain it. Lorne
   

[SUX2BU99]

Thanks, Lorne. I 'think' I grasp the concept of that  lol  I checked my timing again and the balancer groove is pretty much right at the 12:00 mark. Maybe slightly right of it, so I wonder if I have a balancer that is meant for the 12:00 timing pointer.

[HAULIN IT]

That could very well be...but I'd spend the time to verify it to the piston to be sure. Lorne

[1979C20]

Best way to tell is to bring the number 1 piston to TDC on its compression stroke. Pull the plug out, disconnect the power wire to the distributor, put your thumb/finger over the plug hole, have someone bump the key until you feel air push against your thumb/finger. then, grab a long breaker bar and a short 2 inch extension or so. Put the breaker bar on the center bolt of the balancer and put a feeler in the spark plug hole. something like a piece of bailing wire, or a length of soft solder. Turn the center bolt of the balancer with the breaker bar clockwise with the feeler in the hole until you feel the piston pushing the feeler up. bring the piston all the way to the top according to the feeler, and if you feel the piston go back down, turn the balancer counter clockwise to bring it back up. That will give your your TDC, then check the balancer.