Really stupid generic question (c/r and octane)
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From: Toledo, OH
Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
Really stupid generic question (c/r and octane)
I'm going to be finishing up my engine tomorrow and driving the car. I've got a tank full of either 87 or 89 octane in there right now. My new engine has slightly more compression than the last one (9.8:1, iron vortecs) and I just wondered if I'm gonna ping or if I'll be okay. I obviously know I can retard timing and stuff, but lets just make this thread simple since I'll know for sure in about 24 hours.
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
just leave the timing at 30* total. Break it in (flat tappet cam?)... Drive it around, tweak the carb, etc etc... Break in the rings, hard acceleration, engine braking, etc...
Then fill up with 91 octane or better, and bump up the timing after.
Actually, with vortecs, 30* might make best power anyway, and you can get away with the lesser quality fuel...
Just don't lug the car in high gear, low speed, high load. That's hard on the motor, and has the best chance of getting it to ping anyway. Avoid that, avoid overheating it, you'll be fine.
Then fill up with 91 octane or better, and bump up the timing after.
Actually, with vortecs, 30* might make best power anyway, and you can get away with the lesser quality fuel...
Just don't lug the car in high gear, low speed, high load. That's hard on the motor, and has the best chance of getting it to ping anyway. Avoid that, avoid overheating it, you'll be fine.
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Joined: Jul 2006
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From: Dallas
Car: 89 Formula
Engine: LB9
Transmission: MM5
Axle/Gears: G80/GM3
Figure your dynamic compression. There are several calcs on the net you can use, some arguably more accurate than others, but all should get you close. You should always work with dynamic compression when designing a motor to run a particular grade of fuel with a given cam/static compression combo. I'm sure you'll find you'll be just fine just as Sonix states, but learn to love dynamic compression. 
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Joined: May 2003
Posts: 1,995
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From: Toledo, OH
Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
Originally Posted by Sonix
just leave the timing at 30* total. Break it in (flat tappet cam?)... Drive it around, tweak the carb, etc etc... Break in the rings, hard acceleration, engine braking, etc...
Then fill up with 91 octane or better, and bump up the timing after.
Actually, with vortecs, 30* might make best power anyway, and you can get away with the lesser quality fuel...
Just don't lug the car in high gear, low speed, high load. That's hard on the motor, and has the best chance of getting it to ping anyway. Avoid that, avoid overheating it, you'll be fine.
Then fill up with 91 octane or better, and bump up the timing after.
Actually, with vortecs, 30* might make best power anyway, and you can get away with the lesser quality fuel...
Just don't lug the car in high gear, low speed, high load. That's hard on the motor, and has the best chance of getting it to ping anyway. Avoid that, avoid overheating it, you'll be fine.
so you say 30* would be best? alright I'll give that a shot. That's about 12-14 base right?
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From: Saint Clair Shores, Michigan
Car: 1985 IROC
Engine: 350 TPI (block was swapped)
Transmission: 700r4 w/corvette servo
Axle/Gears: no idea
Token!
So youre finally getting that thing running?
I beat you to it! I got a new engine for my camaro after blowing a rod through my oil pan *didnt you do that too?*
But yeah, ann arbor isnt that far, we should meet up some time and find some "insert dirogetory female term*
You get the point
-Blair
So youre finally getting that thing running?
I beat you to it! I got a new engine for my camaro after blowing a rod through my oil pan *didnt you do that too?*
But yeah, ann arbor isnt that far, we should meet up some time and find some "insert dirogetory female term*
You get the point
-Blair
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From: Saskatoon, SK, Canada
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi
9.8 is nothing (for pump gas) when you have the right cam. Mine is a full point more than that and runs just fine on 91.
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From: Chicago
Car: Only a daily driver, but comin home
Engine: I have one that runs ;)
Transmission: Caged hamster that runs really fast
Axle/Gears: They are round, I know that much
I am running premium (which I think around me is 93) on a smidge over 11:1 compression ratio with NO problems and have my timing set at 35*. I was getting pinging when I was using E85 (was trying something there that didn't work to well) and went to regular pump gas and nothing is wrong....except for the leaky valve covers I can't get to stop 
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