Initial and All-In Timing, Summer v. Winter?

[threewood]

I understand several members store their cars in winter and drive during summer but I have a question for members who drive year round.....do you dial back your timing in the summer due to hotter weather / pinging?

My gas here sucks, 91 ethanol is best out of the pumps anywhere in town. I do occasionally cut that with 110 race gas. During the winter I had my timing set at 24/37 all in with vacuum advance hooked up without issue. Recently getting on it I heard it ping pretty loud so I reduced timing to 20/33 all in and no more ping with heavy throttle.

Aluminum Stealth heads, KB237 piston .010" in the hole, .030" headgasket, est 10.4:1 cr, cam 238/242 duration, 108 cl. Never had kickback when starting even at 24 initial. Car runs at 180 degrees, 190 when sitting in traffic in 93 degrees ambient temp.

 

[65-440]

Year round driving, once timing is set I don't touch it ...... Never had an issue, then again my engine is pretty mild, .030 over 383, aluminum everything, 477/481 comp cam, 9.44:1 comp... pertronix ignitor 2

 

[oldbee]

+1 for 65-440. Course “way back” there was only one gas,year round!

 

[Johnpat]

There are definitely winter & summer blend
Gas.
That started years ago,dont think it should apply
to today's cars,but you know our government
You may find you need to run richer in summer
or twik the timing.

 

[beanhead]

Gas no better here. I find that my 440 needs the 850 demon slightly re-tweaked/leaned for hotter weather as the air gets less dense but the timing stays put...22/36@3000. I, too, have alum heads which helps. Static compression's around 9.5

 

[SlinktRR]

the only time i change timing once set is if i get a load of bad gas. Seasonal change i just adjust the carb jetting for lean/rich. Leaner in summer richer in winter.

 

[Paul_G]

There are some variables that must be considered. Heat is the first. In our Arizona winter the engine runs cooler and breaths in cooler air, ignition timing can be optimized for max performance in the cooler weather. As we get in to the heat of summer the engine may ping where it did not in the winter. Higher operating temps and the hotter air entering the engine can make it ping. I have experienced it myself.

It is very hard to keep my coolant temp below 220° in the summer with the AC going when it is above 110° outside. I have experienced some ping in those conditions, especially climbing hills. It is safer to back out some timing like you did. I had to as well. I run 12 base/32 total with vac advance on 91 octane year round. It's just safer.

 

[threewood]

Thanks for the replies. I do need to swap out the rods in my carb because my cruising a/f is down in the low 13s.

I had my timing set where it is after a few members told me I needed more all in timing so I upped it to 37. Which seemed to work fine until recently. It's getting hotter so I'll be driving her to see if it still runs good with the timing backed off.

I hate being limited to 91 ethanol at the pumps but nothing I can do about it.

 

[Billccm]

So I assume you are going to a lean rod? Leaner might make pinging worse?