Slightly Old Gas More Likley to Ping?

Quick question, guys...

I noticed that when my Charger is under WOT, it pinged a bit. I went to a heat range colder in plug and put in some fresh gas. The gas that was in it was maybe a month old? No more pinging.

Fast forward three weeks and the pinging is back. Can gas start deteriorating that quickly? It's the ethanol 93 octane swill with Stabil added. Any ideas?

The engine is a 10.4:1 compression, mild cam, aluminum heads so I know I am near the edge...

as we know gas is crap but I wouldn't think it change in a month. I'd think more likely a difference in temp and or humidity. I'd sub in a slightly stiffer spring for one of your current springs or trim the tips of the weights evenly/slightly till the ping stays away

I keep hearing of these stiffer springs...

I am open to doing this but can anybody here give me a source and part number for these? The only thing I can seem to find are the Accel springs and I have no idea if these are stiffer or even as stiff as what I have now....

Is there a sponsor here who sells just the springs I would need?

Air temp has a significant influence on when/if an engine pings. I run different timing winter and summer.

"I'd sub in a slightly stiffer spring for one of your current springs or trim the tips of the weights evenly/slightly till the ping stays away"

Robert could you explain how this will reduce pinging? I also have a problem with pinging on acceleration with only 32 degrees of timing at 9.5:1 compression. I think my dist has the light silver springs in it though!
Mike

Cjskotni The crane kit of heavier springs is no longer available. I found some ones that worked at ACE harware. Mike stiffer springs and or trimming the weight tips both slow the advance which will stop/slow pinging but you cant go too far & gas is crap & more octane might very well be needed. If you build a monster you gotta feed it what it wants (needs). Mike see what springs you have and find out at what RPM it stops advancing at and is your pinging at WOT or part throttle. what eng what SCR (measured or guestimated?) quench or no quench? what fuel (octane). that's 32 total WO the can added in? what initial what idle speed? ported or manifold.

I have no idea whether Stabil affects the octane rating of fuel, but I never run WOT without running out the winter fuel and having a full fresh tank of gas. Do you use Stabil every tank? I don't think you would need it if the car is started every few weeks. I have only used it when I know the car will likely not be driven for months, such as over the winter.

When I used to race my Valiant on pump gas I found that gas stored in plastic cans or left in the fuel cell for over 2 weeks did degrade. The car would slow down up to 1/2 second in the quarter. I started checking it from the jugs and it would actually change color. This was with 93 BP.

Robert the pinging is at WOT only. CR is 9:5.1 that's all I know. Don't know about quench.
I have 2 silver springs . 93 octane(10% ethanol???) 440 motor ,32 timing without any vacuum advance(MSD billet Dist.)
Mike

in your driveway I would find out at what RPM the slots max out at. that is 32 total with can capped I am assuming? Those "silver" springs may be letting it come in way too fast & 32 total is way too retarded & is hurting you (temp & performance). what eng? (1) post the RPM (2) depending on the ans to (1) we might wanna get some stiffer springs in there. unless those springs are extremely light & even then I'm suspicioning that we might need more octane. I ain't up on whether E10 10% ethanol) helps or exacerbates pinging & (at least here in Nebraska & we grow more corn than anybody) we have a choice & the pump will say if it is E10 or not

Robert they are the very light silver springs,using the blue advance stop bushing(21 deg.) 32 timing(total by 2500) cuz I was trying to get rid of the pinging to no avail. I has initially had the timing at 36.
Thanks Mike
p.s. Sorry for hy -jacking the post but I thought it might shed some light on original posters question.

Different sources of gasoline can have different properties.

The octane listed on the pump is an average of the RON and MON numbers.

Ethanol loves water. Today's vehicles have sealed fuel systems, your Charger doesn't, NC is very humid.

Mike I would set the RPM it maxes out at back to 3000 & the total back to 36 & if it STILL pings I would consider more octane. Wouldn't hurt to confirm true TDC

I'm not going to get into all the timing issues others have tried to cover and just tell of an incident I had happen.

Can gas go bad sitting three weeks in your car? Maybe. The key is, how old was it when you put it in?

My wagon has a stock '77 440 in it. Compression ratio is in the 8's. Back when I was daily driving it, I was running mid-grade or higher because I kept getting slight pinging under load or at WOT.

I tried everything tuning/carb related to get rid of it, to no avail. It was especially frustrating because I knew the comp ratio was so low.

Then, one day I needed to get gas, but found myself somewhere that had only the 87 swill that everyone uses. I expected it to ping real bad after all the issues with the higher octanes, so, imagine my surprise when there was NO pinging. No matter how I ragged on it, nothing.

All I could figure was that no matter the station, the higher octanes don't get used as much, so, they end up sitting much longer than the cheaper swill and basically going bad before they even hit your tank.

From that point forward, I used nothing but 87 and never had an issue.

Now, I'm not saying go run out and fill your tank with 87, but, the gas you're using may be old already and you don't realize it. Unless you have a known source, its a crap shoot what you're gonna get.

My (long winded)