Stock 440+6 Engine Pinging Under a Load - With 93 Pump Gas.

[72ls5fla]

hey all .....

Some facts....
I have the initial timing set to 5 degrees advanced and the vacuum advance is connected.
180 degree themostat - car runs at that temp all the time.
Chysler electronic ignition is installed - orange control box

I usually run about 4 gallons of 112 Sunoco (w/lead) and the balance 93 octane Chevron.
With this fuel mix, car never pings at all - hot/cold or otherwise.


If I try to run just 93 and no Sunoco -   ( we have a 10% ethanol blend too ....      )

When the car is cool - no pinging at all
when it gets hot (running temp or a bit higher from traffic) and the outdide air temp is 85-90, the car will ping under acceloration.

Is there any chance I can get the car to run on pump gas at all?

It will be pretty much impossible to take the car on any sort of road trip if this can't be done.

Any and ALL help will be GREATLY apreciated!!!!     

Thanks in advance.

Bill

[quapman]

Gas with ANY alcohol in it sucks in an old car, but what can we do?

Retarding the timing would be my first thought. Cooling the air/fuel next.

Maybe a plug with a different heat range? Have you blocked off the exhaust crossover in your intake? (Feel free to call me an idjit if a sixpack manifold doesn't have one.)

My 440 runs better with a 165 thermostat. Tried the 180 and got what you've got.

[72ls5fla]

I always run the shaker open to cool the air/fuel as much as possible.

as for the cross-over being blocked, I am pretty sure it is not. The car warms up pretty quickly and the choke works like it is unblocked.

how much further can I retard the timing?  It is 4-5 degrees advanced right now.   Would it help to disconnect the vacuum advance?

I can change to a 165 thermostat and see what happens.

[Strawdawg]

Light acceleration, or heavy acceleration?   What is the total advance?  If under light acceleration, I would start by unplugging the vacuum advance

[72ls5fla]

strangly - under light/mod acceleration.  Under WOT - seems okay (hard to be 100% sure though).

Don't know the total advance - how can it be calculated?

[Strawdawg]

You have to use your timing lite...but, being it is under light acceleration, I would have two guesses....either a little too much vacuum advance, or, perhaps, your power valve is too low a number for the vacuum being pulled by the engine which allows the car to go lean under light acceleration.

As it is easier, I would unplug the hose at the advance and plug it...if this makes the problem go away, then you can stick an allen wrench in the port on the advance and turn it a few turns ccw and reconnect the hose and see if that fixed it.  That should reduce the amount of advance.

[72ls5fla]

I will run my Sunoco 112 blend down this week and try the info above -
I will post back and let you'all lknow how it goes.

Thanks for the great advise.

bill