Is everyone running premium (92 octane minimum) fuel?
- Thread starter praugue
- Start date
cevtv
Founding Member
cenok is family
15 Year Member
in Oklahoma, premium is 91 octane, which is what i run and my timing is advanced to 14* (maybe 15, i don't remember). i haven't run anything lower since i rebuilt my motor earlier this year, i'm gonna try some 89 and see if there's any difference, and the try some 87.
I think premium at most places here is 91, but I think I remember seeing 92. I dunno. I wasn't looking when I filled up the HARBL on the way to work, this morning. 
I run premium in the '86 GT right now with about 14* of advance. Tried running 89 octane (mid-grade), but it knocked just a little at WOT sometimes, so I'll just live with spending the extra dime per gallon rather than backing off the timing.
Frankenstang: The difference in cost between premium and regular is only about $0.20, anyhow, and multiplied by about 3/4 of a tank (10 gallons) it only comes up to a difference of maybe $2 between the el-cheapo 87 octane and the premium dinosaur urine. Being that I only drive the thing on the weekends and, therefore, a tank usually lasts me a week or two, the difference in cost is negligible.
If you're gonna start using the notch for DD'ing and putting a lot of gas through it, then we can always roll the timing back to 10* so you can run the cheap 87 octane crap ... but trust me, you can feel the difference in that car. Otherwise, just bite the bullet and consider that extra two bucks you're spending per tank as getting two dollars' worth more fun out of the thing.
I run premium in the '86 GT right now with about 14* of advance. Tried running 89 octane (mid-grade), but it knocked just a little at WOT sometimes, so I'll just live with spending the extra dime per gallon rather than backing off the timing.
Frankenstang: The difference in cost between premium and regular is only about $0.20, anyhow, and multiplied by about 3/4 of a tank (10 gallons) it only comes up to a difference of maybe $2 between the el-cheapo 87 octane and the premium dinosaur urine. Being that I only drive the thing on the weekends and, therefore, a tank usually lasts me a week or two, the difference in cost is negligible.
If you're gonna start using the notch for DD'ing and putting a lot of gas through it, then we can always roll the timing back to 10* so you can run the cheap 87 octane crap ... but trust me, you can feel the difference in that car. Otherwise, just bite the bullet and consider that extra two bucks you're spending per tank as getting two dollars' worth more fun out of the thing.
Jaswir
Member
87 octane here in both my 5.0 and 2003 GT
Why?
It's cheaper, and burns more efficiently anyway.
Higher octane is not "better" anyway. It's a huge myth. Different engine setups require different octane levels depending on timing, boost, tune, etc. But having a octane number that is high does not signify "higher performance".
Why?
It's cheaper, and burns more efficiently anyway.
Higher octane is not "better" anyway. It's a huge myth. Different engine setups require different octane levels depending on timing, boost, tune, etc. But having a octane number that is high does not signify "higher performance".
It signifies NOT PINGING in the cars that I've bumped the timing on. Advanced timing = more oomph = more performance. Hence, the higher octane.
If you can get away with bumping the timing on yours and still manage to run 87 octane without pinging, then that's awesome. I've just never had any luck with advancing timing without also needing to at least upgrade to 89 octane to avoid detonation - even at 12*, my notch used to ping with 87 octane.
If you can get away with bumping the timing on yours and still manage to run 87 octane without pinging, then that's awesome. I've just never had any luck with advancing timing without also needing to at least upgrade to 89 octane to avoid detonation - even at 12*, my notch used to ping with 87 octane.
I think premium at most places here is 91, but I think I remember seeing 92. I dunno. I wasn't looking when I filled up the HARBL on the way to work, this morning.
I run premium in the '86 GT right now with about 14* of advance. Tried running 89 octane (mid-grade), but it knocked just a little at WOT sometimes, so I'll just live with spending the extra dime per gallon rather than backing off the timing.
Frankenstang: The difference in cost between premium and regular is only about $0.20, anyhow, and multiplied by about 3/4 of a tank (10 gallons) it only comes up to a difference of maybe $2 between the el-cheapo 87 octane and the premium dinosaur urine. Being that I only drive the thing on the weekends and, therefore, a tank usually lasts me a week or two, the difference in cost is negligible.
If you're gonna start using the notch for DD'ing and putting a lot of gas through it, then we can always roll the timing back to 10* so you can run the cheap 87 octane crap ... but trust me, you can feel the difference in that car. Otherwise, just bite the bullet and consider that extra two bucks you're spending per tank as getting two dollars' worth more fun out of the thing.
Oh, no, **** that 10* ****. Premium it is!
Taz92gt
Member
I run 93 in mine it has 14 deg of timing and is lightly moded, it pings under load when anything else is in it.
when my car was N/A i ran 16* base timing and ran with 87 octane and it NEVER pinged at all. since i added the blower i run the best gas which is 91 in oklahoma. i havent tried running lower octane, i run 12* base timing with the blower on , i even ran it at 15* with the blower and never got pinging. i set it down to tone it down some.
alot of cars are different, my car loves extra timing but some are picky. alot of mileage with carbon build up will be more prone to detonation.
you just have to find what your car likes.
alot of cars are different, my car loves extra timing but some are picky. alot of mileage with carbon build up will be more prone to detonation.
you just have to find what your car likes.
bloopbloob
Member
i'm with foxfan88 on this one too. i ran my car at 18* on 87 octane all spring and summer without any pinging. on the hottest day of the year,(35*C), i heard a slight ping, and only over 4k rpms, so i dropped it to 16* and thats where it sits. never pinged again.
i bet i could get away with 20* on 87octane right now because its so cold
Might have more to do with environmental conditions than the differences between cars, per se. Down here, we generally have almost NO humidity, and when the temps get above 100* I usually had to back the notch down to 13* or 12* because it would still ping under WOT at 14*, even with premium fuel.
cervinistang
New Member
i need a timing lesson.. im a noob
what is it?
how do i adjust it?
what is required when adjust'n (such as gas)?
what does this do?
what is it?
how do i adjust it?
what is required when adjust'n (such as gas)?
what does this do?
cenok is family
15 Year Member
timing is the point on any given valve/cam lobe when the combustion process starts during the combustion stroke of that cylinder. for example, if you advance your timing to 14*, the spark plug will ignite the gas/air mix when the valve is 14* before top dead center of that cam lobe. whew, i hope i said that right. lol. to adjust timing:
Use chalk or a bright paint or a soap pen to highlight 0 and 14 or however much you want to advance your timing on the harmonic balancer.
Remove the spout connector that is about 6 inches out/below from the distributor.
Connect your timing light.
Loosen the distributor hold down bolt. Only enough so that you can turn the distributor.
Start your engine.
Point your timing light at the timing marks and slowly turn your distributor until the timing pointer lines up with new timing mark you made.
Turn off the engine.
Retighten the distributor.
Start your engine and recheck timing to make sure it did not change after the distributor was retightened.
Reconnect spout connector.
advancing it usually means you should use higher octane gas, but, as you can see, some don't have to. hope this helps
cervinistang
New Member
when stopped for a while i get on/off purrs... can that be a problem related to this?
like prrr.....stop.....prrrr...stop...
clock work like though
like prrr.....stop.....prrrr...stop...
clock work like though
Timing is the point at which your spark plugs are directed to fire in relation to the compression stroke of the piston. The stock setting of 10* BTDC = "10 degrees Before Top-Dead-Center." So, advancing your timing makes the spark plug fire that much sooner.
The idea is to get the fuel to BURN, rather than EXPLODE - changing timing will change the point of compression at which the fuel begins to ignite and, thus, how it will combust. If you advance timing too much, and you wind up with detonation (pinging), which can damage things and, in extreme cases (such as with forced induction or nitrous) totally kill parts of your engine. (Punching holes in your pistons and fun stuff like that.)
To change it:
1. Buy a simple timing light, clip the power leads onto your battery terminals, and clip the pickup over your #1 cylinder plug wire (the front-most cylinder on the passenger side). Make sure you keep the cables out of the way of the serpentine belt and the radiator fan, or else serious harm (and humiliation) may result.
2. With the engine warmed up to full temp and then shut off, pull the spout connector out. It's a funny little plug thing coming off the wiring harness by your distributor's ignition module. PUT IT IN YOUR POCKET. DO NOT LOSE IT.
3. Clean off your harmonic balancer so that you can clearly read the numbers on it. I always forget this part for some reason, and don't realize it until after I've started the car, then I have to shut it off, crawl under there, and scrub away while feeling like a dummy.
4. It's a good idea to take a marker or chisel or SOMETHING to mark the position of your distributor where it's at, FIRST ... just in case you flub things up. (It happens.) Now, LOOSEN, but DO NOT REMOVE the bolt for your distributor hold-down clamp. It's a 1/2" head bolt, usually. If you don't have A/C, this part's easy; if you've still got the compressor installed, that stupid thing is a PITA to reach.
**DO NOT ROTATE THE DISTRIBUTOR WITH THE ENGINE OFF!** You'll just wind up moving the timing to some unknown position, and you'll hate yourself for it. Don't ask how I know.
5. Start the car. It'll probably stumble and run kinda funny at first. That's because the spout connector is (or should be, at least) sitting in your pocket and not plugged into the harness. The ECM is not able to add or subtract timing at its merry whim, so what you'll be getting here is the BASE TIMING reading.
6. Point the timing gun at that pointer on the passenger-side of the harmonic balancer. Pull the trigger. Unless you've confused your timing gun for your girlfriend's/wife's hairdryer, you will be rewarded with a flashing strobe light that will illuminate the position of your timing, as per the numbered marks on the balancer; otherwise, you will only be rewarded with a whirring noise and a stream of warm air, and your woman will yell at you for getting grease on her hairdryer.
7. Pay close attention to where your timing marker is at BEFORE you do anything. Got it? You sure? Okay. NOW, you may SLOWWWWWWLY start to rotate the distributor. IIRC, counter-clockwise advances timing, and clockwise retards timing. Whatever. You'll see the pointer move when you do it. You won't have to move it very far at all. Usually, there's a mark for 0*, 10*, and 20*, with five marks between each. So, each mark roughly equals 2 degrees. Rotating the dizzy so the pointer goes up two lines (about 1/8") will advance your timing to 14*.
8. Once you have the timing set where you want it, let go of the dizzy and DO NOT TOUCH IT. Go shut off the motor. Tighten the hold-down bolt snugly, but avoid moving the distributor at all. I try to only loosen the dizzy up just enough to where I can baaaaarely rotate it, because if you make it too loose, you can sneeze at that thing and throw off the timing from where you set it when you last looked at it.
9. Plug your spout connector back in. You didn't lose it, did you? No? Good boy. Here's a cookie.
10. Disconnect your timing light, throw your stuff in the trunk, crank 'er up, and go for a spin. Listen closely for any pinging at WOT (sounds like marbles banging around in your motor). If you experience any ping, repeat the above procedure and back the timing down just a hair - half a mark (13*) or down a full mark (12*). Do this until you reach a happy compromise between added power and no pinging.
Most importantly, post back with your results.
The idea is to get the fuel to BURN, rather than EXPLODE - changing timing will change the point of compression at which the fuel begins to ignite and, thus, how it will combust. If you advance timing too much, and you wind up with detonation (pinging), which can damage things and, in extreme cases (such as with forced induction or nitrous) totally kill parts of your engine. (Punching holes in your pistons and fun stuff like that.)
To change it:
1. Buy a simple timing light, clip the power leads onto your battery terminals, and clip the pickup over your #1 cylinder plug wire (the front-most cylinder on the passenger side). Make sure you keep the cables out of the way of the serpentine belt and the radiator fan, or else serious harm (and humiliation) may result.
2. With the engine warmed up to full temp and then shut off, pull the spout connector out. It's a funny little plug thing coming off the wiring harness by your distributor's ignition module. PUT IT IN YOUR POCKET. DO NOT LOSE IT.
3. Clean off your harmonic balancer so that you can clearly read the numbers on it. I always forget this part for some reason, and don't realize it until after I've started the car, then I have to shut it off, crawl under there, and scrub away while feeling like a dummy.
4. It's a good idea to take a marker or chisel or SOMETHING to mark the position of your distributor where it's at, FIRST ... just in case you flub things up. (It happens.) Now, LOOSEN, but DO NOT REMOVE the bolt for your distributor hold-down clamp. It's a 1/2" head bolt, usually. If you don't have A/C, this part's easy; if you've still got the compressor installed, that stupid thing is a PITA to reach.
**DO NOT ROTATE THE DISTRIBUTOR WITH THE ENGINE OFF!** You'll just wind up moving the timing to some unknown position, and you'll hate yourself for it. Don't ask how I know.
5. Start the car. It'll probably stumble and run kinda funny at first. That's because the spout connector is (or should be, at least) sitting in your pocket and not plugged into the harness. The ECM is not able to add or subtract timing at its merry whim, so what you'll be getting here is the BASE TIMING reading.
6. Point the timing gun at that pointer on the passenger-side of the harmonic balancer. Pull the trigger. Unless you've confused your timing gun for your girlfriend's/wife's hairdryer, you will be rewarded with a flashing strobe light that will illuminate the position of your timing, as per the numbered marks on the balancer; otherwise, you will only be rewarded with a whirring noise and a stream of warm air, and your woman will yell at you for getting grease on her hairdryer.
7. Pay close attention to where your timing marker is at BEFORE you do anything. Got it? You sure? Okay. NOW, you may SLOWWWWWWLY start to rotate the distributor. IIRC, counter-clockwise advances timing, and clockwise retards timing. Whatever. You'll see the pointer move when you do it. You won't have to move it very far at all. Usually, there's a mark for 0*, 10*, and 20*, with five marks between each. So, each mark roughly equals 2 degrees. Rotating the dizzy so the pointer goes up two lines (about 1/8") will advance your timing to 14*.
8. Once you have the timing set where you want it, let go of the dizzy and DO NOT TOUCH IT. Go shut off the motor. Tighten the hold-down bolt snugly, but avoid moving the distributor at all. I try to only loosen the dizzy up just enough to where I can baaaaarely rotate it, because if you make it too loose, you can sneeze at that thing and throw off the timing from where you set it when you last looked at it.
9. Plug your spout connector back in. You didn't lose it, did you? No? Good boy. Here's a cookie.
10. Disconnect your timing light, throw your stuff in the trunk, crank 'er up, and go for a spin. Listen closely for any pinging at WOT (sounds like marbles banging around in your motor). If you experience any ping, repeat the above procedure and back the timing down just a hair - half a mark (13*) or down a full mark (12*). Do this until you reach a happy compromise between added power and no pinging.
Most importantly, post back with your results.
bloopbloob
Member
what all can change where the timing should be? does degreeing a cam affect this? what about any mods? (besides f/i etc that need less timing)?
Similar threads
- Locked
