Engine: Pinging & Running On.

[Aussie Hawk]

I have a 289, '62 GT, from what I believe the engine was rebuilt about 15K miles before I bought it. From day one it had a pinging problem, so I adjusting timing and fuel mixture the pinging decreased but the running on increased!!! I have recently been talking to a previous owner, (not the one I bought it from), and he said it had the same problem when he had it.

My therory: the heads have been taken down too far and now the higher compression is causing these problems.

Q1: Does my therory hold water?
Q2: Would thicker head gaskets be enough to lower the comp and stop the problem?

[bezhawk]

Here's a list of things you might check:
It could be excessive carbon build up, wrong heat range spark plugs, spark plugs not tight, timing, distributor advance plate sticking, too rich with too fast an idle, and poor seating valves (retaining heat). After checking the timing (with the vacuum advance disconnected), I would check the plugs. If they look good, try a heat range colder and see if that helps.
After all that, and you still have problems, the thicker head gaskets are good for lowering the compression about half a point.

[JoeHall]

If you have gotten the pinging under control, the run on may be something you can learn to live with: Idle it down to about 550 rpm; if it is an automatic, try shutting it off in gear; if a stick, leave it in gear and leave the clutch out; if it has AC, turn the AC on before shut down. Excepting the idle down, he above are ways to place a load on the engine before shut down.

[Aussie Hawk]

[QUOTE=bezhawk;649617]Here's a list of things you might check:

It could be excessive carbon build up: Yes, that had crossed my mind.
Wrong heat range spark plugs: That too.
Spark plugs not tight: They're tight.
Timing: Timing has been tried at several settings.
Distributor advance plate sticking: Haven't checked it.
Too rich with too fast an idle: Checked and discounted.
Poor seating valves (retaining heat): Haven't checked.

Joe,
I've had the idle down as afar as I can, and turning it off in gear, (yes, it's an auto). It just drives me mad, and sounds terrible. Very hard to make a cool entrance at a car show, or gathering, when the Hawk sounds like a diesel running on two less cylinders that it should. ;-)

[SN-60]

To: Aussie Hawk,----- You might try a thermostat that opens at a lower temperature

[PackardV8]

Check to confirm the exhaust heat riser valve is fully opening.

FWIW, I always block the intake manifold heat riser passages between the head and intake manifold. Use thin sheet stainless.

One simple fix for running on is the same one the BrandX OEMs used. They added a bolt-on solenoid. The solenoid was energized when the ignition is on and was used as the idle speed stop. When the ignition is off, the solenoid retracts, allowing the carburetor throttle blades to fully close. No air, no run on. The solenoid is still fairly common in wrecking yards here. Maybe someone on the forum has a BrandX with one on it.

jack vines

[Bud]

When the engine was rebuilt, were the pistons replaced. It's possible that flat top pistons have been installed in the engine raising the compression ratio. If that is the case, higher octane gasoline should reduce the problem. Also if the engine has a Prestolite distributor installed, the centrifugal advance mechanism could be worn causing timing problems. That along with a bad vacuum advance unit can cause the engine to run on and detonate because the spark is retarded raising the combustion temperature and causing parts in the upper cylinders such as exhaust valves and or chunks of carbon to overheat and cause pre-ignition. Bud

[Dan Timberlake]

"Timing has been tried at several settings"

Is the current setting 4 degrees BTDC or the "IGN" mark, preferably on a damper whose TDC mark has been confirmed to match #1 piston's actual TDC within degree or 2.