well just as the title says, my car pings like a speaker at 4500+ with good gas, ie chevron, bp, texaco...

but with "cheap" gas that everyone hates, the car runs like 10x's better... no pinging at all...

what could it be?

both are 93 octane... i'm not getting why "cheap" gas is running better...

 

seems like my car does that too...... do you have the h engine code?????... ive hot and 85 TA also couldnt tell you y its like that... even when i go from running 93 to 87 it seems better too.... i thought it was just me.. SRY i couldnt help

 

How odd.. well easy solution.. keep running the cheap crappy gas

 

Urban is quite the scholar, very informative ane quite the joker at times. 93 octane is unheard of here, premium is 91 and that is the best it gets. Your older motor does not need that high octane! You are wasting dough using it, the newer higher reving engines require a higher octane (or so they are told) Save your money and buy regular unleaded, your older engine does not like the 93 because it is harder to burn!!!

 

I try lol

Alot of it comes down to compression ratio, iron vs. alum heads, use of power adders, and a few other things. What's your whole setup 12 second ta?

For comparison my 97 LT1 has 10.1:1 CR and alum heads, and it says in both the owners manual and on the fuel door to only use premium unleaded, at least 91 octane. runs like crap and pings on 87 or 89.

 

your not talking to me i know that for sure, midgrade gas, (89 octane) pings at 2800rpm cheap or good gas....

my engine runs cool, cylender head temps are 190*, compression is like 10.2:1 with an iron head...

inital timing is 18*, and total is 36*....


i'm still having a hard time figuring out how the cheap gas does it...

 

Yeah I'm thinking you'll want at least a 91 octane judging by your setup.

Very odd.. maybe it has something to do with the way the cheaper gas is made, what chemicals are in it (MTBE or ethanol or whatever) perhaps

 

i'm beginning to think so as well, i have such a large cam, i either have to have the idle at 1500rpm, or 1100rpm, and super rich, so i can put it into gear without stalling... With it running rich, the good gas tends to foul the plugs and i find myself having to stead the cylenders once a week.. the cheap gas seemingly doesn't, there is a chemical somewhere here that stunts the explosion...

 

hmm hopefully someone with more experience in this area can post up, but I think you're right, it has something to do with the way the cheaper **** is made.

 

its not that i'm complaining, its just i have a BP credit card for one reason, is like the best gas out and i'll pay extra for it... ut now i cant really use it...

the motor makes an estimated 450hp... their RHS votec castings, flow very nice...

the cam is rather large, but at the same time tame...

234/244 duration @.050, and .520/.544 lift... so it has lots of overlap for compression relief...

 

I know how you feel about paying for better gas. The best I can get here is 91 octane at chevron, and that's what I run.. at a whopping 3.35 a gallon.

 

12sec, what is your timing at idle? That cam isn't unbelieveably large, I'd think you could get an 800RPM idle, without fouling plugs...
It'll need gobs of timing, manifold vacuum advance should help you be able to start it too... Just a random thought...

with things as they are, *shrug*, cheap style gas is more plentiful as there are more of the cheapie type stores... Great!

 

I have an MSD ProBillet Distributor, no vacuum advance...
i run 18* advance at idle... no vacuum can...
i run 36* all in at 3200rpm...

I run a 650cfm speed demon, very nice, stock jets.

the car just wont run correctly at idle unless i idle it rich... if i run it leaner, it has nothing for torque down low, and stalls when put into gear. We set idle with a air/fuel gauge, so i know what it was running as far as afr... but it would stall like crazy. nearly undrivable...with an 1100rpm(out of gear) idle, and running pretty darn rich, she'll move very swiftly, but i have to steam the carbon out like once a week.
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and the general concensus around i asked, is that "cheap" gas has water in it, a little is unnoticable in most cars, but obviously, that little bit of water, has a distict cooling effect as it vaporizes with the fuel, that it stops pinging due to high temps from compression.

at the same time, there are also other not so explosive addatives, and well.. they help stop pinging in my case.


i just need to figure out my idle, she idles super high, andruns rich, and its getting to be quite expensive... i drive maybe 20 miles a day costing me around 30-40$ in gas daily!

 

oh yea, run manifold vacuum advance, if you can get a vacuum can. The crane 96001 will work, it's adjustable and whatnot. $36 or so I think.
Then go up to like 24* at idle or so. That's fairly bit cam.

Also, what heat range of plugs? Maybe go hotter?

 

sonix, i have a MSD Probillet Distributor, without vacuum advance... really is too late to add vacuum now...

I got rid of the "Stock" hei system, for the much more reliable, stable and accurate distributor, the msd... my timing doesn't float around, with the hei i had, which was brand new, it would flux about 2* back and forth... with the msd, nothing, like when she was a fuel injected car...

The heat range is the coldest i could get, equivient to a r42t, i had r45t's but she would ping like a piano, and took them out with the new dizzy, and well, not as much high rpm ping...

 

I was in the same boat a while back, I was using 110 octane race gas, and it would ping and studder, then I went to 108 octane gas, same thing, I tried 100 octane and it ran a TON better, but it hestiated off idle, then I was using E85 (the corn oil gas), and it got worse.

Then finally I needed gas in the car and drove to the local BP and put 93 octane in and ....POOF!!.....no more problems.....and this is in an tad over 11:1 compression, iron head, full MSD ignition, 35* total timing, 6800 rpm redline small block.....I still don't understand it why it runs better with premium, but its cheaper than $5 a gallon

 

yeah, offence man, but i tried hard, i reaaly did...

but can you resay that to where i can understand it...

 

ok, not familiar with that distributor, I thought you could toss on a vacuum can. Can't you? Is that distributor actually setup with no provisions for vacuum advance? geez, that's the reason your plugs are fouling...

Well, if you can, adjust it up to mid 20's timing at idle, and the same 36* total. I guess you can do that with that high end distributor? I had to modify my travel slot with a welder, but that's a stock HEI setup so...

More timing will let you lean it out at idle, and bring down the idle speed. I have a 227/233 cam, and I had to run 24* at idle to get it to well. It'd run at 500RPM idle speed if I wanted. I shot for 750rpm usually.

ok, R42t's should be good for you, with your CR there. Have you checked where the heat line is on the ground strap? That'll tell you if you've got the right heat range. If it's halfway between the center electrode, and the threads area, like right at the bend almost, then you're ok. If it's closer to the center electrode, go cooler, and if it's too close to the threads, then go hotter.

 

the only thing i hate about that dizzy, is that i can only shorten advance travel to 18*, which is where it is... i'll have to improvise..... maybe weld, something to help, otherwise.... i'll be running it locked out..

what are advantages and disadvantages to running it locked out...

i'm sure i could run a balast resistor of sorta so that the ignition wont kill the starter...

but other then that what can i expect as far as bennefits and problems?

 

The olny thing i can think of casuing this is your dynamic compression is too low to warrant the use of the high octane gas.

They definately have a different mixture of additives and tend to burn cold and run like crap with low compression.


Or something like that...

 

as much as i want to say that made sence, i catn....


how can my dynamic compression be way too low to not need the 93 octane, but still ping...

 

So anyone got any idea's as to how to help my idle...

 

did you try cranking up your timing? Try bumping it up high, like 26* at idle, don't go WOT with it, but try and get your idle right with that. If that helps, then shorten your advance, so you still have 36* WOT, and 26* at idle.

speed demon? you have idle-eze? Probably need the extra air at idle...

 

yes i definately need more air...

i do have to say, demon's customer support is beyond expectation... it is worth it to buy a demon, and talk to real experts...

Pretty much the knowledge i aquired is to reset the carb, and set timing to idle at 900rpm, and go from there, resetting meaning throttle plates, idle screws 1 turn out, and idle-eze 2 turns out... and adjust timing to make it idle at 900rpm...

he said if this could not be done, the only way to add more volume without richening it up, is to enlarge the air bleeds, and a 5/64" drill bit has a 20% increase in air, and will give me the neccessary extra air to lean my engine out and have a stable idle...

 

seemingly works great guys, idles at 900rpm, and pers, and doesn't foul plugs....

 

most awesome.

 

yeah pretty much what it came down to was the carb is too small, as purchased for my cam/engine.... so the amount of air it was made to flow at idle was less then my cam wants...

By increasing the air bleed flow, i allowed to carb to flow 20% more air volume, that had nothing todo with the air fuel mixture, so i was able to increase volume without richening the carb...

Car runs great, and pulls much harder....

yet, she still pings with good gas...

something about pure gas isn't so good...