Timing question FE

[Zorm]

Got the engine out, replacing the freeze plugs, water pump and timing set since I'm there. Set to TDC, (timing mark on harmonic balancer lined up to timing bracket, dizzy pointing to # 1cyl, verified with long screwdriver in #1 cylinder). Remove he timing cover and the timing marks are just a hair off. I look at the harmonic balancer and see that the painted mark that I used to set TDC is actually at 10 and not 0. I also noticed that the timing chain is kinda loose.

So, would it be due to the mark on the balancer being at 10 causing the marks to be a little off or the loose chain? With the new chain, do I line the marks back up to each other? I don't know why the timing is set at 10*, this truck been in the family since 73, its had 3 engines, not sure if this one is a 390 or 360 and who put it in. Dad passed in 08 and I got this in 09, Mom does not know any history on the truck.

thanks for help.

[sparky72]

The PO probably set the idle timing at 10 and put a mark there to make tuneups easier. Someone had done the same thing to mine.

In theory, TDC is TDC. When you have the balancer lined up at 0°, the dots should line up real close. You could check whether it’s the chain by moving the crank back and forth to see how much play there is (should be about none).

[Furyus]

I would line up the marks on the gears, and put on a new timing chain. Then your balancer should be at zero. If not, you can make a piston stop from a spark plug, and a bolt. Lots of info on making it. Rotate the engine clockwise until it stops. Make a mark on the balancer. Rotate it counter clockwise until it stops. Make a mark on the balancer. Measure the distance, and top dead center will be exactly in the middle of those marks. If it's not at top dead center, the balancer is off.