Timing vs. harmonic balancer?

[Darrell Goodwin]

Forgive me if this has already been answered; I've looked but still don't understand. I have an '82 "Custom Deluxe" (which is neither) with a 305 engine. It ran great until recently the motor died in the fast food pickup queue. I replaced the coil (wrong) and then the ignition module and that fixed the problem. Then I replaced the rotor, condensor, plugs and plug wires to prevent any other potentially pending untimely malfunction. But now it runs like crap. I figure the timing needs to be set after replacing the ignition components. I bought a cheap Harbor Freight timing light (it has the advance knob but I leave it set at zero.) The timing mark has been painted white, and while looking from underneath, I put a white dot on the opposite side of the harmonic balancer just as a visual reference. It's not 180°, just a rough indicator of how much I've rotated the crankshaft. When I use the timing light, I see the dot, the actual timing mark doesn't appear.

My technique for over 50 years until now has been an 'old-school' method that has worked well for me: I nudge the distributor a little bit and drive a couple miles observing performance. I do this as I handle routine daily business, and as each adjustment improves performance, I know I'm going the right direction. Now it starts usually on the first crank, no longer backfires (but occasionally misses) but I haven't hit that sweet spot where it accelerates with power. The Quadrajet 4-barrell seems maybe a little bit too rich, but how could the timing mark be so far from the pointer that it doesn't even show under the timing light? I carefully changed one wire at a time, so didn't mix them up. It had that plastic identifier on top of the distributor until the new wires went in (they don't have the little bumps to hold it.)

Could the harmonic balancer have slipped? If so, how does that happen and how can it be fixed? Or am I overlooking something that would be obvious to a more experienced person? Tomorrow I'll start from the beginning by cranking to #1 TDC and go from there, as well as verify the vacuum is still as perfect as it was last year when I rebuilt the carburetor. My old-school method has always gotten results pretty quickly, but I've been nudging the distributor numerous times a day for over a week, and while there is improvement, it would be nice to be able to use the timing light and dial it in and lock it down. Comments, criticisms, suggestions are all welcome. I'm an old dog ready to learn a new trick.

 

[Blue Ox]

I'd still recheck the firing order of your plug wires. Replacing all that stuff shouldn't have that significant an effect on timing. Either that or you have a faulty component.

And how about the cap? You didn't mention replacing the cap.

 

[80BrownK10]

The balancer can slip. The outer ring moves on the inner. And the timing marks no longer mean anything at that point. Not saying this happened but it can

 

[Octane]

When you bump engine over to align the timing marks at 0° mark,where is the rotor pointing? #1 cylinder? If it is,check your plug wire order.And if not pointing at #1 then it jumped timing

 

[wlwarnke]

I’ve actually had a balancer slip or the owner installed the wrong balancer. Weren’t some of them keyed differently?

To confirm, I’ve stuck a zip tie or small Allen key down #1 spark plug hole so that the piston would push it up. Then crank (manually), when the piston reach TDC (approximate since we are going cave man) check the mark on the balancer. Make a new mark if needed with a paint pen.

With #1 at TDC, make note of which distributor terminal the rotor is pointing toward. That is #1 wire. Standard is point towards cylinder 1, and/or the terminal just past the batt/tach terminals but reality is that it doesn’t matter, as long as you know which one it is.

Before going through all that, yes, confirm firing order and all the normal stuff. Also, vacuum advance should be disconnected when checking timing (well, depending on if your using ported or manifold vacuum it may not matter but it’s easier to just disconnect it).

Can also using the timing light to confirm mechanical advance works, rev engine and see if timing advances. Confirm vac advance works by sucking on the hose connected to the canister, confirm timing advanced.

Damn I must be old to remember carburetors and distributors.

 

[Corvette Ed]

The balancer can slip. The outer ring moves on the inner. And the timing marks no longer mean anything at that point. Not saying this happened but it can

I’ve had this happen twice,years ago,both times on a 305. Mine slid back rubbing the timing chain cover.