With gas at 4 bucks I switched to 87 octane it seems to run ok but don't know if I am doing any damage to my 10 to 1 small block.

Jerry just keep reading the plugs and watch the timing. Depending on the cam and the dynamic comp ratio 10to1 with alum. heads can live on 87. And even live on 89 oct with a less forgiving dynamic.

Harley , I have iron heads and hardened valve seats

Depends on how hard you are driving your car, if you take it easy you can get away with lower octane. to me it's not worth the risk to save a few bucks now and end up spending a whole lot later. Every car and situation is different (weight, gear ratio, tranny type, engine specs, temperature, altitude, timing, etc..). If your car is running fine on 87 then there really is no reason to run Premium. As mentioned above read your plugs and see what they tell you.

With iron heads I would say your pushing it with the 87. I also agree that there are many things that factor into it. That's why I mentioned the dynamic comp. ratio, because it tells more of the story. I also run 92 as cheep insurance with my 427. Yea I could get away with 89 but The few bucks it costs me to run 92 is worth it to me.

Hmmm now you got me thinking . . . .
btw I have 4:11 rear and 4sp tranny , and not a really radical cam.
and I'm not going to risk it , I don't buy much gas for it anyway as I only drive it on weekends anyway.

I would put 93 back in it. I tried 87 once in my 10.25cr aluminum head engine and I could hear it rattle. I have never put 87 back in it. Pre-ignition is not good!

My Owner's Manual states I should use Premium grade.

And with 15 gallon gas discount coupons from the local grocery store, Farm Fresh the wife gets, 93 is cheaper than 87 at the pump. Once in a while, they run a special, buy $100 worth of groceries and get a $1/gal off for 15 gallons.

But they still don't give a gas discount when you purchase beer.........

8.5:1 = 87 octane :D .....But my 87 octane engine = :(

93 octane premium in the race car
87 octane in the drive car, truck, mower, chainsaw etc.

I have to run 93 octane in the Camaro AND in my BMW (required)

Used to run the prem.. but after reading the thoughts on it on the TC site.. decided to go with the lower grade. No probs. The cost up here for #1 is way out of line!:eek:

capt

With iron heads I would say your pushing it with the 87. I also agree that there are many things that factor into it. That's why I mentioned the dynamic comp. ratio, because it tells more of the story. I also run 92 as cheep insurance with my 427. Yea I could get away with 89 but The few bucks it costs me to run 92 is worth it to me.
I was wondering about what gas I'll run in the 427, Harley. Is 92 octane really ok? What's your compression at?

I've been running 93. Next time I'm empty I think I'll try a few gallons of 89 to see what happens. It's not the end of the world if it pings a few times. If it does, I'll just bump the timing back or head back to the pump and fill up with 93.:thumbsup:

I did my break-in with cam2 fuel because of the Ethanol. I went through 2.5 gallons of gas in 30 min. I plan on running a mix of fuel when the car hits the road.

I have iron heads 461's with hardened seats @ 9.7to1 ratio timed out at 14 degrees with 38 total I am having no issues with detonation.

regurlar gas dropped to $3.77 here the other day.
I used to run 87 with 9:1, iron heads and small cam.
Now I use 93 with 10.5:1 and aluminum heads, I could probably get away with 87 because of the heads and cam but wouldn't want to try it.
I love how the rednecks out here think by putting race gas or premium in their regular work trucks they will gain power, I'd bet they would loose a few horse power...

I live in minnesota.I am running a stock build 69 350 ss motor. however I have a 69 302 cam, lifters,intake and carb on top of this engine.It will ping when hot on 92 pump gas.So
I use a 50 percent blend of e-85 and 87 octane fuel. The engine loves thi combo,no ping
smoother idle and better response at low rpm. I was also able to add 6 degrees of additional timing. here e-85 is plentiful and sells today at 2.69 per gallon.

Tom, doesn't the E-85 eat regular rubber fuel hose and carb gaskets? I thought i read that you couldn't run that in a car set up for "dinosaur" fuel. E-85 is $3.24 a gallon here, i wonder if i should try that in my jalopy.;)
My father-in-law was complaining on the way back from the car craft show about pinging on 87. He asked what i was running and i said; "87, this thing could run on whole milk if needed!!" I thought he was going to wet himself!

Not real worried about the price of gas for the Camaro, but stick with 91 or better. Have ran a few gallons of Cam II with a nice smell and no gains (10.6:1 steel heads)

The e-85 mixed the way I have been doing has not caused any problems so far.I have run 3000 miles and have noticed other problems have gone away such as hot heat soak and some vapor lock on real hot days or in traffic. so far so good give it a try not much to loose as long as the burn is good

I use 93

With compression ratio nearing 10.5 with the 1094 gasket i run 93 octane.

I run 93 octane but hell I got a 502 with a 8/71 blower.

Hmmm now you got me thinking . . . .
btw I have 4:11 rear and 4sp tranny , and not a really radical cam.
and I'm not going to risk it , I don't buy much gas for it anyway as I only drive it on weekends anyway.

Jerry.. I have been running 94 Octane Gas and 118 Leaded Race Fuel at about a 80/20 ratio. For every 8 gallons of 94, I add 2 gal of 118 fuel. The motor runs cooler and doesn't ping. See if that ratio is something you like. :)


Kev

Jerry.. I have been running 94 Octane Gas and 118 Leaded Race Fuel at about a 80/20 ratio. For every 8 gallons of 94, I add 2 gal of 118 fuel. The motor runs cooler and doesn't ping. See if that ratio is something you like. :)


Kev


Kevin. How are you? Did you ever get the 396 in the Camaro?

I use pump 91....thats all we get.....

I run 87 and use the "Octane Supreme 130" additive to bring it 89. I used to run it on 93, but it didn't seem to run as well. I dropped it to 87 and the Octane Supreme 130 and it runs better. According to the Octane Supreme 130 website:

Engine Octane Needed

Compression Ratio Min. Max.

8:1 87 92

9:1 89 96

10:1 92 100

11:1 96 102

12:1 100 108

Typical requirements-some may vary

You can run e-85 and mix it with regular gasoline? Does it run better or it that just so you can run an 87/e-85 mix to save money? I couldn't run it even if I wanted to. The closest e-85 pump to me is 45minutes away. Kind of defeats the purpose.

Sure, i'll give it a try. I need an excuse to rebuild my 396 anyways (if i ka-blam my 355)!

Cheaper per gallon does not necessarily mean cheaper operating cost. Each engine and application will have its own needs but fuel economy also comes into play.

In my area 87 octane is at or just under $4/gal while 91 octane is usually about 25 cents higher. This is about a 6% increase in cost. If by using the higher price fuel, you can get 6% higher fuel economy, the actual cost is the same as you will be using 6% less fuel. If the higher octane will permit more agressive tuning such as timing/advance curves and/or higher compression the benefits may be greater making the more expensive fuel actually cheaper to use. I've found this to be the case on a couple of my own cars. After retuning, I liked the way they ran on higher octane fuel enough better that it was worth the extra cost for that alone. The fact that I gained enough mileage to make fuel costs cheaper was a welcome bonus.

Each vehicle, drivetrain and use thereof will be different and your mileage may vary.:D

Sure, i'll give it a try. I need an excuse to rebuild my 396 anyways

l:)

Kevin. How are you? Did you ever get the 396 in the Camaro?

Doug...
Sent an email.

Kev

I ran 89 on my 10.7 pass.9:7:1 comp bbc.
When its cold I run 87 in it.
If its realy hot and I might get stuck in traffic I run 93 just to be safe.

I only have a 9:1 at the most and it seemed that when I ran 93, it didn't run as well as when I run 89.

I was wondering about what gas I'll run in the 427, Harley. Is 92 octane really ok? What's your compression at?
10.78:1 aluminum heads and a real good quench area.

I only have a 9:1 at the most and it seemed that when I ran 93, it didn't run as well as when I run 89.
that's about right the higher octane burns slower so you need to bump up the timing or go back to 87 or 89.

I also mix 93 and 110. 10.6 to 1 with iron heads. I dont drive the car much so the $$ has not been a factor for me yet.

that's about right the higher octane burns slower so you need to bump up the timing or go back to 87 or 89.

How far should the timing go? I currently run 18* initial and 34* total.

How far should the timing go? I currently run 18* initial and 34* total.
Your timing is set almost where I have mine 18*/36*. Without knowing the rest of your combination and how you drive it a little hard to say if you should run 87 or 89. I would keep the timing where it's at for now. That's about where most guys I know run there's. I've played with more timing without issue but I was pushing the limits for power and decided to play it safer.

that's about right the higher octane burns slower so you need to bump up the timing or go back to 87 or 89.
I heard you need to retard your timing when running a higher octane fuel? The person may have been wrong but I can see why you would. Don't you retard your timing when your running nitrous any way?

Typically more octane will support more timing. You retard the timing if you don't have enough octane and the engine is pinging.

1970 350 w/RPM Air Gap, Thunder 650, 4.10's, Powerglide, Crane Hi-6 ignition, Pertronix dizzy, Comp 270H cam w/Rhoads variable duration lifters, 1 5/8" headers, 2" dual exhaust, stock heads, stock bore. The car seems to run good. I get 15hg of vacuum at idle. Car idles at 850rpm in park/neutral and 650 in drive. Pulls hard. The carb has .101 primaries and .104 secondaries w/6537 metering rod and the pink springs. I know it sounds rich, but it's the way the car wants it. I have tried other combos, but this is how it runs the best. I have a SMI stage 2 Q-Jet on the way to go with a Performer RPM(non Air Gap) manifold. I have a slight part throttle stumble and Sean relates it to the Air Gap feature. I think the car is going to run much better once the Q-jet goes on, both cruising and torque wise.

I heard you need to retard your timing when running a higher octane fuel? The person may have been wrong but I can see why you would. Don't you retard your timing when your running nitrous any way?
Ryoce hit it on the head. And yes you do retard the timing when running nitrous, but not because it raises oct. All nitrous does it increase cylinder pressure and add more oxygen to help burn the fuel. The increased cylinder pressure and the added fuel is why you retard timing.