I'm a new member and have enjoyed the roundtable section. I was interested in what you do when you have to buy lower octane gas on a trip. I've been trying differant timing setting to see what the lowest octane I can run. Any other suggestions.
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Mike J

You could add a can of actane booster to every tank, but I figure the extra 10 cents a gallon for Plus would cover the cost of the booster. My car runs fine on Plus or Super.

My problem was that I got in an area that only had 87 octane. The car didn't run to good & will not shut off.(diesels badly).I try to run 91 to 93. I was reading a article on toulene on another site & the charts. A bottle of the additives only raise the octane about 3 tens%.I did start carry bottles of the octane boost with though.Guess if that happens again I'll just get enough gas to get to the next station.
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Mike J

I'm about to type more than I know for sure but that never stopped me before.
The higher octane fuels today are a certain percentage alcohol. Now I've never been one to turn down alcohol you understand BUT I believe that certain rubber components of our fuel systems could be affected by that alky in the gasoline.

I just built my 'cookie cutter' SBC so that it runs just fine on unleaded and low octane. In my previous car I used "ReLead" and it seemed to work out just fine.

My .02

Jim
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Time is natures way of keeping everything from happening at once.

I'm from Iowa and every gas station sells gasahol. But I'v never drank it. Haven't put it in the car either. Not because I'm Afraid it would harm the motor but the car came from Michigan where they didn't have gasohol. I don't want the gasohol to clean all the varnish out of the tank and plug everything up. That is what happen when people first used it. Its only 89 octane. I can get the car to run on 89 Fairly well but doesn't shut off to good.
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Mike J

when 'gasohol' first came out, a different alcohol was used; methyl alcohol, (methanol), this raised havoc with fuel systems. they use ethyl alchol now, (ethanol), i havent heard of any problems with it, the change took place several years ago. i use it in my cars, lawn mowers etc., i haven't had any trouble at all. one of my cars had 150,000 miles on it when i started using it, it now has 185,000, no problems. unless you are superstitious, i wouldn't be afraid of using it.
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project...39 ford pickup

Short of putting an anti-diesel solenoid on the car you can either put it in gear (if'n it's a stick and kill it that way) or just mash the gas pedal. In effect this will flood the engine, only slightly, and kill it.

How's that?

Jim
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Time is natures way of keeping everything from happening at once.

I tried the the idle stop soleniod. I didn't help. Got my Chilton's out. It said timing or carbon build up.(i try not to let that happen) Or use better gas. I do shut it off in gear,its an automatic but it still helps.( shuts off fine with 93) Thanks for any info.
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Mike J

Try operating the idle solenoid with a toggle switch instead of the ignition. Drop the idle for a few seconds before you kill the ignition. Might help.

I knew a guy once that ran a manual choke cable to his distributor. He had built stops on the distributor so he could slow the timing down for starting and stopping, and speed it up for driving and racing. Pretty primitive (I think Model Ts came with manual spark advance) but it solved his problem.


bjb
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There's a world of difference between "good" and "good enough".

This sounds like a good idea. Will try it.
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Mike J

Octane boosters out of the can do little to enhance the real octane of the fuel even though they provide great lubricant and cleaning for the fuel system. A little 12 oz. bottle just doesn't have the means to do such in so far as octane is concerned.

However, add a gallon of toluene and it raises the octane to over 90! That's RON+MON/2 by the way. Toluene is the additive that makes racing gasoline what it is. Visit www.wauknet.com/douthitt/pumpgas.htm for an enlightening lesson in fuels, octanes and how it applys to you and yours.

The idle/turn off problem can be manifested by several things. Too high of a mechanical idle setting, too hot of an themostat (cooler works better because it slows the flamefront that keeps the car running), higher octane.....same reason as before and too much mechanical/static advance...run no more than 8 degrees with a vacuum advance. I would change to the lowest temperature of thermostat that you can get and play with the rest. You can get it so it works.

Steve Jack
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SOUTHEASTERN GOODGUYS REP

Thanks for the web address That is the best article on gas I belive I have ever read. I fried a motor in my old truck running part AV gas and never related it to the gas I always blamed it on somthing else but looking back it kinda makes sense. It was a 10.5:1 350 and running a Qjet I used to mik 7gal AV to 13 hi test and it seemed to run great but always hotter and I just thought it was because I was working it harder but it was leaning out...great bit of info thanks again.
Dr. Pepper

RETARD YOUR TIMING A DEGREE OR TWO! Yes I am yelling here, BTW. This should help the detonation from running the lower octane fuel.
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Damn, I wish I had more time.
35 Ford Pick-Up

I read the article Steve Jack suggested. Will buy a New Timing Light today. My ear isn't working..
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Mike J

Steve, once again you have come to the rescue with straight, easy to understand info.
I live in NH where MBTE is the additive as well as an increasing source of drinking water well polution; there is even a move afoot to have it banned in the state.

I have a 68 Impala SS-396 ragtop which has run fine in past years on pump gas until this month when the "reformulated" blends came out for the summer driving season. I now ping with even mild acceleration and dont want to retard the timing any more as performance had already suffered with last years setting.

The car is a low mileage numbers matching one so for "resto" reasons the Q-Jet will have to stay. Im not sure what was done internally but since it came from NC anything is possible! It has a non stock cam for certain, likely dealer installed.

Questions: What was the stock jetting and what would you recommend? Would jetting alone enable me to return to factory timing on 93 Octane or should I experiment with Toulene also? Would sending out the carb for professional rebuild and modifications be worthwhile?

Tnx, Carl

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Carl
Automotive gold is everywhere; you just have to learn how to dig for it

Carl........the rejetting of your carb is likely to do nothing for the detonation that you are experiencing, unless you have an overlean condition to start with. In some cases, a richer mix might take away some of the detonation, but the product of an overly rich condition is poor performance.....so you might as well set the timing back to start with.

The muscle cars of the past are notorious for their dynamic peak cylinder pressures, due to the cam grinds and compression designs that contribute to the detonation issue. This manifests itself with alterations in the fuel formulas meant for seasonal applications.

Summer blends are configured for each local region based on the vapor pressure points for each region. For example, a summer blend for Denver, a high altitude, semi-arrid and moderately warm climate, would never work in New Jersey, where it is located at sea level, moist and hot.......completely two diffening vapor pressure points! So....the formulas are all mixed up wherever you go demographically. The summer blends do tend to take about 3 points of Octane rating away according to my reseach and depending on location and of course the hot induction charge is a culprit as well.

My recommendation is to run a cool thermostat, try another brand to see if their octane is different, rethink timing and if the timing thing doesn't interest you, a gallon of toluene with a fill up is a start on the road back to an octane level that you can live with. It might only take half that....but that's a good start for a couple of octane points.

Steve Jack
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SOUTHEASTERN GOODGUYS REP

you could be running a slightly lean condition, with using the oxygenated gasolines of today. i run a 428ci police interceptor, 1968 vintage with 10:1 comp, bored, balanced, heads ported, slightly cammed, hi-rise, headers, 650 holley doublepumper on 89 octane pump gas. i prefer to use 92 octane, it likes it better,but can't buy it in the small town where i live. i can get by with the lower octane unless running it hard, then it will have a tendency to knock. i jetted the holley a couple of jet sizes larger and went one step cooler on the plugs and also run a cooler thermostat. i run my ignition timing @6 deg. initial with 36 total and vacuum advance on ported side; all seems to work ok that way.(you don't want to overjet the carb though or you'll start to lose performance, as steve jack stated). in my case i prefer to run slightly rich to help keep cyl temps down,verses lean and and worry about a lean meltdown. just my thoughts on this.
rickd :-)
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project...39 ford pickup

Tnx guys for the info. Im not even sure what the timing is , just backed it down until pings stopped last summer.
Started experimenting last evening with Xylene as an additive, couldnt find any Toulene locally.
The tank was near empty anyway so put in 20 gallons of 89 octane. With .25 gal of Xylene I noticed no difference after about 10 miles of driving. With .5 gal the pinging is only at severe loading when floored in Drive at around 30 mph. Also disconnected the TH400 kickdown lead to better able to force pings.
Will have to find Toulene since it appears to be the higher by volume in race fuel.
Will continue testing as time permits but the goal is to get back to stock timing with 89 octane.....maybe a bit of 93! Its going to be a long summer.
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Carl
Automotive gold is everywhere; you just have to learn how to dig for it

Carl.......look at commercial paint stores for Toluene and certainly auto paint suppliers as well. Some hardware stores such as ACE carry the stuff in gallons.

Toluene is the real octane enhancer........so try that first before getting too down on detonation.

My muscle car friend went around a few weeks when he bought his Chevelle with detonation. When he finally shown up with his car for the first time to show it to me he was excited but....he was disappointed in the detonation issue. I simply went over to the 5 gallon toluene can and dumped a couple of gallons in.....started the car and rocked it back and forth to mix ........and voila...no more ping! A big chevy grin and hard second shifts were his again!

Steve Jack
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SOUTHEASTERN GOODGUYS REP

i have been real interested in the info here on boosting octane.i just read an add in HEMMINGS for real tetraethyl lead additive.(probably not spelled right). i have seen this add in there for months.anyone tried this stuff,or is it too good to be true.the number is 219-232-6430,an individual. i think i will call him and see what gives.....
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dalecarbuff

Tetra-ethyl lead or TEL sold in little cans does little to enhance the octane.....and is polluting as all get out. If you refer to the web address that I previously posted it should clear the air about this.

I have been researching this subject for years and belive me....toluene or xylene is the safest and best way to gain significant octane boosting. There is a further site that is written for mixing your own. www.team.net/sol/tech/octane_b.html is the place to visit. I usually leave the tranny fluid and spirits out.

Steve Jack
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SOUTHEASTERN GOODGUYS REP

Steve Jack, I was looking, at the lacquer thinner, at the hardware store. It had several different chemicals in it. Toulene was listed first. Does this matter?
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Mike J

Makes a difference........don't use lacquer thinner. Toulene can be commercially bought somewhere in your vacinity. Toulene is sometimes refered to as Tolunol as well....and I have seen it in 5 gallon cans at Ace Hardware stores. Now that is not to say every one of them willhave it since they are just francises!

Steve Jack

ps.....sometimes I type so fast that I spell Toulene "toluene" when my fingers go faster than my brain. I hope this doesn't screw things up!...Sorry
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SOUTHEASTERN GOODGUYS REP

Steve,
you suffer from that too? I thought it was only me that had the brain/finger timing issue. My Sun timing light didn't help a bit.

Now, the detonation, pinging, pre-ignition deal.

With my engines, over the last several years, mostly NON emission machines, I've subscribed to the "run the timing up till it rattles, then back it off a bit" method. My T-Bucket with a cookie cutter 350/350 works well with that. I wound up about 18 deg btdc and it worked out.

My dad swore by water injection. He ran the most horrendous initial spark lead in so many cars and always ran water on them. With the spark lead, and then eliminating the pre-ignition with the water he did some bizarre things with early, turbocharged VW sedans. Things like the mid 13's with just the blower, cold air inlet, and water. I saw him do it. It was amazing.

Anywhoo, there you are.

Jim
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Time is natures way of keeping everything from happening at once.

Yep.....the water injection units worked because they affected the flame fronts performance or lack thereof. The cooling of the induction charge and the added density of the charge with humidity slows the advancing flame tremendously.

If you just look at the detonation thing as a slow burning process that will produce a peak pressure at some point in the process and then figure out how to slow it down so that the bulk of the pressure happens after TDC, then the rest is easy.

Things that slow or eliminate detonation are slower buring fuels (higher octanes), colder induction charge (either through the actual reduction in temps of the air or by the reduction in the engine surfaces thru the cooling system, reduction in dynamic compression pressures (either with cam timing or static compression ratio design), higher combustion chamber heat transfer (aluminum is a reducer of heat in the chamber), ignition timing, special design cylinders - that help control the flame propagation or burn, and special ignition systems that also help control burns.

Steve Jack


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SOUTHEASTERN GOODGUYS REP

gentlemen.........this is a reply to all of you from a new member who has been a street rodder since the 60's.........I've been in the racing business for 25 years......in case you can't tell, I was in auto shop in stead of typing class(with all the sissies) . what a fool, trying to hunt and peck!!!!!!!!!!anyway I saw your round table and questions and semi thoughtful answers about synthetic oils and was gratified that most were using them but not totally for the correct reasons.....more on that later......I know that most of you live in the general vicinity of a race track, circle, drag strip, roadcourse etc...you dont have to be a cemest or have to mix or mess with dangerous compounds...If you have electronics in your hot rod get some unleaded race gas.It wont bother your system and if you have used the electronics package from anything with a computer it will sence the octane quality and automatically advance.....all others, go buy 5 gallons of 110 race gas and put in 2 or 3 gallons per tank..your temperature will drop, the motor will smooth out and it will help your mileage..........your car will love it so will you..If you want to put more in it wont hurt anything but your wallet...race gas burns slower and cooler..........whow !!!!!!!!!!!!!first time around and I get writers cramp......hpee this helps, I'ts sure a lot simpler..............teebag
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teebag

Went to 91 octane and the car is running good. Noticed its not as loud inside.
I put a half a tank of 90 octane gasohol and the car wants to diesel a bit again. I haven't change the timing. It seems to be running ok though. It seems like the motor has loosened up with the lower octane. Haven't had anything plug running the gasohol yet. Noticed that the engine vapor locked on a warm restart. Doesn't start as quickly, but I'm just trying to find a happy medium. Getting close I think.
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Mike J

Mikej......I hate to break it to you, but gasohol is not what your looking for for hi po use unless you jet the carb for such. It also can cause certain rubber and plastic parts inline to dissolve....yikes!.....so stick to one or the other. The mix of ethanol and pump gas tends to lean the carb out as well. This would be productive to set the detonation off and again........sorry.

You can get your car adjusted to it though.

Steve Jack
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SOUTHEASTERN GOODGUYS REP

Mike, I also live in Iowa and have used gas with alcohol almost exclusively for many years. The varnish problem you referred to earlier might cause you to clog a fuel filter or two, shouldn't get more severe than that. Steve is correct in that you might again get some detonation IF you are jetted borderline lean in the first place.

Thanks for all of the input. I know I can run on the lower octanes now if I have to, without changing anything, but I'll go back to 91 plus.
All the info helped. Good reading. Steve Jack thanks for pointing the way. This lowered my operating temp about 30 degrees by getting everthing tuned right. And the 18 psi cap keeps the water in the radiator. Now running 200 in town, 180 on the highway.
Have run gasohol on all of my other cars and never have had any problems.


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Mike J

MikeJ.........congratulations on sticking with it....and thanks for the cudos!

Steve Jack
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SOUTHEASTERN GOODGUYS REP

Timing was on 8 deg. Vaccum line was hooked to the manifold port. Changed to venturi vaccum and no more ping. The dieseling problem was that the throttle plate were open to much.(throttle cable was to tight)Adjusted idle valves. Set idle speed with the idle stop solenoid and it now shuts off in park.
This motor is a 9:1 comp. I'm going to still try to go to a lower octane now. Thanks for info on gas and timing.
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Mike J