For the first time, I tried putting super in my 72 comet (stock 302) and it started stalling. It never did this with 87 octane...what does everyone else use? I tried super just to see if it performed any better... now not sure if I should adjust or just go back to 87. Thanks
Higher octane fuel actually burns slower than lower octane. I would not use it unless you have a problem with detonation (pinging) on acceleration, dieseling on shutdown, have your ignition greatly advanced, or are pushing high rpm's. If used when not needed, it can actually enhance carbon build up in lower compression engines, and currency evaporation in your wallet.
High octane is for high compression engines. A stock 302 from the Maverick era is a low compression engine. I don't think the Super would cause your stalling problem though.
if simply adding premium fuel to the tank is causing a motor to stall out?.. then you should be looking at the QUALITY of the fuel.. not the octane rating. Doesn't matter how much you pay for it.. everyone gets bad gas at one time or another. Old carbs on old motors are more sensitive and EFI drinks up the water without hiccuping as hard so many people just never even realize it, is all. and friendly FYI for the OP here.. you can run premium in ANY of these old low compression engines. Have personally done it for hundreds of thousands of miles through the years. BUT.. unless you recurve the ignition and recalibrate the fuel curve to take advantage of the premium fuels improved power capability?.. it's just money down the drain for no good reason. Regardless of compression ratio.. I will ALWAYS use premium on any engine that can be tuned to take advantage of it. I'm not alone there and that's just what power crazed gear-heads do. Also increases detonation resistance headroom even when the ignition/fuel isn't fully dialed in all the way towards max power capability(for any particular combination of parts). I call that cheap insurance for anything that's being hopped up or maximized. Another benefit of running premium gas on something that doesn't get used often enough to regularly burn through full tanks to keep the gas fresher is that even after sitting for 2 months.. the remaining octane will be higher than regular that has been sitting for the same amount of time. Works very well for lawn equipment.
There is no more horsepower in a gallon of Premium/Super gasoline than there is in a gallon of regular. The high octane gasoline is less volatile, so it reduces the chances of pre-ignition (detonation) or "pinging" in high compression engines. You're not gonna (here we go again) "tune" an 8:1 compression 302 to make more power from 92-100 octane gasoline. Advancing the hell out of the ignition timing is not my idea of "tuning". In any case, high octane gasoline won't hurt the low compression engine one bit, but is a complete waste of money.
yeah.. well I've also run avgas in low compression engines and I can tell you fact that more power can be "tuned" into them. The proof's in the pudding.. not the magazines or the internet. I would also add to this the fact that lower compression motors have very poor mixture speeds at lower rpm due to insufficient squish characteristics of the combustion space. What this equates to is an engine design that will not tolerate heavier amounts of ignition lead without knocking. In essence.. the low compression being combined with lower octane creates a massive tuning block and has nothing to do with the btu''s being extracted from the fuel.. cc for cc of fuel being used. It simply restricts the ignition lead that could be used to increase power under the torque peak. More average power within the existing powerband.. low as it may be for this kind of motor.
Premium gas will not make your car not run.plain and simple if you think so then you have a lot to learn.
I read your post and this on the internet... http://www.fuelexpert.co.za/canirunavgas.php I really liked this bit of info... "Because AvGas has no taxes and duties on it, use on public roads is illegal and if found could result in your vehicle being impounded."
I've always heard AVGAS was bad because it's oxygenated to run at high elevations, didn't know about the lead stuff. Thanks for the link.
That pretty well sums it up all in one shot and I should have lead with(pun intended) that and quickly ran away to avoid the usual heated caucasus which come from straying too far outside the status quo. It's like republicans vs democrats with all the damned lines in the sand around here sometimes. Now I know how Nader must feel. Yep. Been more than 15 years since I broke that particular law. I used to drive my SCJ Torino right into the local airport and paid the guy after I put a half tank of the stuff in. Then I did a burnout coming out of the airports driveway, sped home, and then procedded to rip off every mattress tag I could find. I'm such a rebel that way. When was the last time you did a burnout of sped around in your car on public roads, Frank? Pretty sure that law enforcement frowns on that too. Plus, I know for fact that the tickets are bigger. If you've raced long enough.. on the street or the track.. I'm 100% sure you've run guys that were burning the stuff. It used to be really popular with racers and good bang for the buck. I know there are also some turbo guys still running the stuff today because it's cheaper then setting up/running meth injection(at least that's how the think about it and I have no confirmation of it being factual). Any combination of parts just needs to be "tuned" for it is all. Works best for high compression deals but even the little guys running much less compression can make a few more ft/lbs of torque with it too. All depends on how hard you want to work for that last little bit of gain, is all. As for the oxygenation?.. that I didn't/don't know but using oxygenated fuel in many racing classes will get you kicked out due to the unfair advantage which may be "tuned in" from using it. So there may be something there too. Don't care much more about it nowadays than I did when I actually used the stuff and just tuned the motors to any arbitrary ignition lead numbers that it liked to make more power. I still tune the exact same way today too. The motor gets what the motor likes for improving power.
LOL I have an old car I want to get rid of. I should put some Av gas in it and them tell them that I put it in so maybe they'll tow the POS away!
It's not like anyone is gonna catch you running AVGAS. I don't think the AVGAS police are pulling people over and checking their fuel tanks for illegal fuel.
so was it mixed different when you used it? "Avgas may be suitable for some race cars that don't have catalytic convertors or oxygen sensors and are rebuilt often enough that the TEL(lead) build-up is not an issue. The deposits left when TEL(lead) is burned are corrosive and damaging to valves, valve guides, valve seats and cylinder heads. Lead deposits will also block oxygen(lambda) sensors and catalytic converters and foul spark plugs even after only a short use. Also, 100LL has a chemical package added to make it perform at high altitude, and that isn't the best thing for motor vehicle performance here on the ground."
