gearheads78

The marker shows 8 advanced through 4 retarded. If seems to ran best on 0. Is 0 really a built in advance setting? Even 4 advanced it wanted to run on after shut off.

2blu442

Hi Richard, this is the new to you big cruiser you bought? Does it look like the outer ring on the harmonic balancer might have shifted? I confess, I use the timing mark as a starting point, then time by ear as to what runs the best.

John

MDchanic

Yeah, zero is not "right."

If you really want to know, use the method of your choice to determine TDC on #1 and see if the balancer mark has shifted.

I also believe that on these years, there are punched lines to show whether the balancer ring has moved, but they'd be awful hard to see with the engine in the car.

- Eric

gearheads78

So want should the setting be? The marker cuts off at 8 btdc it looks like. That does not seem like it would be enough initial setting??

MDchanic

To specifically answer your question:

1971 455cid:
185 HP 8° @ 1100 RPM
225 HP 8° @ 1100 RPM
265 HP 10° @ 1100 RPM

Don't know which one you've got, but none of them is anywhere near zero.

- Eric

gearheads78

So is the mechanical advance already started to move when you rev up to 1100 rpm? It idles about 600rpm.

ah64pilot

Depending on how the distributor is set up the mechanical advance shouldn't come in until around 2000 rpm or higher. I assume you are timing it with the vacuum advance unconnected and plugged. Zero degrees is way too retarded...I would verify that the outer ring hasn't slipped by checking it at TDC. Also, you will do yourself a huge favor if you get timing tape to put on the balancer, once you know where "ZERO" is.

394olds

You stated that with your timing set at 4 deg, it wanted to run-on after shut down - ie ignition off. Gasoline engine run-on after ignition shut down is caused by an excessive idle speed setting - not the initial advance setting - think about it - the ignition is off - there is no spark so the distributor settings have no bearing on the engine continuing to try to run.

It's running-on because the throttle plates are cracked open and fuel and air are getting to a hot engine with enough inertia to keep it firing by compression ignition - diesel.

The only bearing advanced ignition timing has to run-on is that it will cause the engine to idle faster when in operation. Thus correcting this by slowing the idle speed by closing the throttle plates will starve it for fuel in the ignition off mode.

The engine is trying to tell you that at 4 deg it is running better and please try giving me some more advance AND oh by the way slow my idle speed down.

An 8.5:1 compression 455 (1971) will take a lot of advance.