# Type of Gasoline



## Dozermatt (Dec 24, 2013)

we have a 1966 GTO Tripower, WS block and the #093 H.O. heads, what kind of fuel do I need to be putting into this? We have a premium here but its only 91 octane. Any thoughts?

Thanks!
Matt


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## geeteeohguy (Feb 2, 2008)

I have the same engine/combo, but it's 1965. 91 octane doesn't cut it. I run 91 mixed with TEL130 octane booster (the only booster that works) or mix race gas with the 91. It's a big reason I don't drive it very much. You can back the timing down to about TDC (from 6 degrees) initial and drive it on 91, but it will tend to be sluggish and run a bit hot. These engines need 95-100 octane.


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## rvp986 (Sep 19, 2012)

Would anyone mind keeping this gas burning question going, a bit longer? Don't intend to butt in or rain on your tread, but this subject causes curiosity for me, as well. 

I have a '69-400. GTO with the standard 4-Rochester Carburetor. I eliminated the points, condenser, old style rotor, distributor cap (standard ignition equipment) and have switched over to the newer style HEI PerTronix D1200 Flame-Thrower. Quite honestly the car was a complete and true "frame off" restoration, engine/body overhauled and totally rebuild. No bolt unturned. The car is now (finally) in the body shop after that point in time beyond my expertise (time for the expert body man) and getting ready for paint, very soon. The engine (in the car) is wrapped in shrink wrap with break-in oil in the pan and never turned over... not even one complete revolution. I will be installing a new fuel tank, new fuel pump (already installed), new fuel lines (already installed), etc. So, this is all brand new and ready to crank over with... hopefully, minor adjustments, keeping our fingers crossed. 

My same question.... What type of fuel and/or additives should I be using. Sounds like 91 octane just doesn't cut it, or at least give suggestions and opinions. Pretty expensive project, as some of you well know. A lot invested here and want to do things right. We do come across 93 octane here in Nebraska, from time to time and as you all know this is a big ethanol state... Granted, I'm a farmer and promote ethanol for obvious reasons, but I'm not saying this is the correct product to use in a 44 year old classic as nice as this. In fact, I'm sure, we could call this another subject for another time.

Been working on this project for a bit over three years now. It only gets the best. That includes care, as well, and we're getting really close. 

Thanks in advance to all for your ideas and opinions.


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## geeteeohguy (Feb 2, 2008)

Simply put, your ignition system has nothing to do with the octane requirements of a stock high compression Pontiac V8. In fact, no power is gained in changing the points and condensor for an HEI unit. Merely the convenience of not maintaining a points system. When new, and now, these engines require about 100 octane fuel. Some owners get away with 93 octane in cooler and more humid climates. I've been driving these cars continuously, day in and day out, for over 35 years now, and I can tell you, they used to run better on the 94 octane leaded I could still get then. The addition of alcohol has been the worst thing to happen to our fuels, as it destroys carburetors, fuel pumps, fuel lines, and fuel tanks. It also decreases gas mileage and causes the car to run too lean. So, with the poor fuels available today, you are looking at a compression ratio of about 9:1 with and iron headed Pontiac, or 10-10.5:1 if you are running aluminum heads. That is the reality. No amount of fancy products or bolt on whiz-wangers will make any difference. High compression needs high octane.


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## Bill H (Aug 4, 2013)

This has been a topic I've been interested in as well. 

I haven't had the car out for more than just some quick trips around the block, but plan to remedy that in the near future and I've been debating my fuel options. Sounds like I know which way I'm leaning after reading this, and other similar threads.

Luckily I've got some options available, not only in town but also close to my house, 93 octane (standard "Premium" at the pumps), Sunoco 100 octane and 90 octane with no ethanol.

Seems I'll be going the Sunoco 100 octane route with an additive for the ethanol over the 90 octane non-ethanol.


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## Chris-Austria (Dec 23, 2010)

I agree to everything geeteeohguy said.

As far as I know the Ethanol in the fuel will react as soon as it has absorbed the most water it can, which will lead to a chemical reaction and set the bad substances free.
Premium fuels over here (Austria) have less Ethanol than Standard so you should always choose the best and probably most expensive fuel a gas station near you offers if you own a high-compression Pontiac.
It's also a bad thing to not run your car for a longer time if your fuel lines, fuel tank, carburator are full of gas. Gas gets older and it will build that "yellow to brown crusty crap". It's always a good idea to have the gas tank full to reduce the amount of condensed water that will lead to the chemical reaction I mentioned and to run the car from time to time. This will reduce the bad influence of the Ethanol in the gas ( and if you burn the fuel you will need some new, so it doesn't get too old  )

You will need at least 93oct if your SCR is about 9.5 to 10. Above that you shoulnd't even try to use 93oct with the timing retarded if you ask me. Get race gas or higher octane at some other gas station. A good cooling system, carb a little on the rich side and not too much timing surely helps, but changing the timing is just a band aid and no insurance to be on the safe side at all.

I also want to mention the need of ZDDP in the engine's oil. This is the only additive I use.

There are also rubber fuel lines available that are for use with up to 10% Ethanol, not every rubber line should be used if your ethanol level is that high.

I would rather lower the compression or get aluminium heads than do some band aid's that could destroy the engine a little later instead of now if you cannot get higher octance or don't want to use race fuel.


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## BearGFR (Aug 25, 2008)

Good job, Chris! :cheers

Bear


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## geeteeohguy (Feb 2, 2008)

.....and he didn't have to blow up a 428 to learn it, either, like yours truly!!


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## PONTIAC CLASS (Feb 4, 2014)

Wanting to learn at every GTO turn in the road how was a 428 "blown up".
Thanks.


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## geeteeohguy (Feb 2, 2008)

I was 'getting away' with running 89 octane gas in my '65 GTO with a 3.55 gear and a 4 speed and a '69 428 with tripower. I was commuting 100+ miles to and from work at the time, and gas was expensive and I was using a lot of it. The 89 was cheaper than the then-available 92 octane by quite a bit. I ended up breaking 4 or 5 pistons....the ring lands were broken off. From detonation. The crank was hammered, too. From detonation. It was detonating for many miles and I never heard a thing. And I was in my early 20's at the time with perfect hearing. I learned my lesson on that one: if you have high compression, you can't 'cheap out' on the fuel. I still have that GTO, but now it has a 389 in it, and it sits most of the time because, you guessed it, it needs race gas to run. When I built it many years ago, there were few options. I am currently toying with the idea of fitting it with aluminum heads so that I can DRIVE it, like I do my low compression '67!


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## rvp986 (Sep 19, 2012)

Not only am I a lover of Pontiacs and especially GTO's, I am also very addicted to Harley-Davidson's. Just checked out my dealer's fuel prices where I'm a chapter member as I knew they sold 100 octane. Here the current prices in Lincoln, Nebraska...

BUFFALO GAS Prices

WE HAVE HI-POWER GAS!

91-Octane $3.699

95-Octane $5.499

100-Octane $7.799

*WOW!*

Seems there's quite a spread between all three, but I can attest my Harley's all run better on 95 and really 'pure' like kittens on 100 octane. Normally, I get by just fine on the 91 Octane, but if I even try use anything less, I get the infamous knocking sound and they don't start worth a crap. Switch to the good stuff, and they pop right off and handle very impressively. Guess I'll be treating my GTO, before starting her for the first time to 100 Octane, but at 17 gallons per fill (or at least for the first fill) and paying $7.799 per gallon or $136 I think I'll be driving it on Saturdays and Sundays like I had originally planned and only for cruising and going to the good 'ole Drive-In Movies. Guess that's what I intended/wanted it to do in the first place. 

Thanks guys for your worthy input!


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## Chris-Austria (Dec 23, 2010)

I forgot to mention... the higher above see level, the better it can deal with the detonation problem. But in reality you would have to live at 10.000 feet or something to get away with 10.75 and 93oct. Don't try it unless you live in Nepal or something like that.
But if it's on the edge I would say 98oct over here where I live (1500 feet) should be enough... but I use the 100oct anyway as it is just a little more expensive. ($7.90 for a gallon instead of $6.90)


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## BearGFR (Aug 25, 2008)

Is there such a thing as "too much" octane? Yep, there sure is.

Octane rating is a measure of how quickly the fuel burns. It is NOT a measure of how much energy the fuel releases when you burn it. (In fact, in general, the slower a fuel burns the less potential energy it contains - and the less power it will make.) The purpose of the octane rating is to "control" the burn rate of the fuel so that in the high pressure, high heat conditions of the combustion chamber the fuel does in fact continue to just "burn" and not "explode" - which is the root of detonation. So, the perfect fuel for an engine if you're interested in making power, is the one that has "just enough" octane to stay out of detonation, but doesn't burn so slowly that it "gives up" power.

Bear


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## geeteeohguy (Feb 2, 2008)

Bear is absolutely correct. The less octane, the more 'energy' in the fuel due to its faster burning. Higher octane fuel burns slower. The higher the octane, the slower the burn. This is why it works well with high compression. A car that will run without detonation on 87 octane will run _slower_ with 92 octane. But if you run too low of an octane for your engine, it will do harm. I just wish I could easily get fuel like rvp986...Where I am, ALL fuel contains 10% alcohol, and the highest octane at the pump is 91, at over $4 per gallon. Makes me want to move to somewhere like _TEXAS_!!


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## Bill H (Aug 4, 2013)

I remember doing an experiment back in HS shop class when we were covering fuel systems.

two different test tubes, one with 87 octane the other with 93. Lit them both, the 93 octane had a nice, steady, slow burn that moved along the length of the tube. The 87 blew up the test tube.

Puts it in perspective.


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## BearGFR (Aug 25, 2008)

geeteeohguy said:


> Makes me want to move to somewhere like _TEXAS_!!


Bring it on  I know where there's a house in Garland with a nice 4-car garage, insulated, has its own separate HVAC system, extra power, sink... 

Bear


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## geeteeohguy (Feb 2, 2008)

If I did that, I'd have to put a stroker crank in my '67 to keep up with the Bear's! And I'd _still_ be left in the dust!!! LOL..............Have to admit, when I went to Chickasha OK two years back, I was amazed at the availability of 'real' stuff for sale at real gas stations, sporting goods stores, etc. In CA, _anything_ perceived to be more dangerous than a Nerf football has been legislated out of existence!!


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## rvp986 (Sep 19, 2012)

AMEN to that. I'm not going to get into politics. My grandfather told me once, you never talk about Politics, Religion, or Sex (in that order) unless you want to get yourself into trouble. I'm thinking California might be in that equation as well, but you didn't hear me say that. I just suggested it. I do like Texas, thought.


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## skurfan (Sep 19, 2012)

Ok, so after reading all of this....what is the recommended octane for my 1967? 400, pretty much stock with a little more than stock cam rebuilt 35 years ago. I have been running 91 unleaded with a can per tank of Octane Supreme. It seems to do fine, but if there is better I would like to know. I don't know what my compression is. Also, where in Lincoln, Nebr is that 100 octane? I get there a couple times a year and could pack some big gas cans.


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## geeteeohguy (Feb 2, 2008)

"....I'm thinking California might be in that equation as well, but you didn't hear me say that..." rvp986, that is the funniest thing I've heard all week!! Of course it's absolutely true. Nailed it! Skurf, your car needs high octane.....95 to 100, but you may be able to get by with 93 in humid MO. with the right tune and a good cooling system. The TEL130 is expensive, but a quart added to a 20 gallon tank will absolutely increase the octane to sky high levels. Not cheap, but it actually does work, so nothing wrong with what you're doing!


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## rvp986 (Sep 19, 2012)

For Skurfan... 91 runs fine in my Harleys, too. But nothing wrong with a little more insurance using 95 or 100. An investment protected. That's how I look at it. Fuel isn't cheep, but a ruined engine, especially after the buck we all shell out taking care of our cars. 

The high octane fuel, in Lincoln, NE, is at the Harley Dealer. The dealers name is "Frontier Harley-Davidson". They are located on west "O" Street, just to the south of I80 as you're headed west out of the city. You can Google them and find them, no problem, but here's the link... http://www.frontierhd.com/ 

Ya, I plan to use as high of octane as I can get. Normally, I can find 91-93, depending where in Nebraska, but if I pull into the Harley Dealer I'll be sure to use 100 octane. Put way to damn much money into this car to destroy :shutme it now. Part of my life too.


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## ZooKypr (Jan 15, 2014)

Dozermatt said:


> we have a 1966 GTO Tripower, WS block and the #093 H.O. heads, what kind of fuel do I need to be putting into this? We have a premium here but its only 91 octane. Any thoughts?
> 
> Thanks!
> Matt


I'm always running 93 octane and every gas station in the area has it.


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## skurfan (Sep 19, 2012)

There is 92 with no ethanol in it 50 miles west of me. Cost me a third of a tank to get there and back though. Thanks for the inputs.


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## xconcepts (Jan 4, 2009)

So I only have 91 here, would my best bet be to start using the Kemco supreme 130? Anything else I could use?


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## geeteeohguy (Feb 2, 2008)

Either the Kemco Supreme 130 or race gas. No other 'octane boosters' are worth the bother. The Kemco Supreme 130 works great in my '65 mixed with 91. I'm at about 11:1 CR (milled small chamber #77 heads). Expensive, though, and takes the fun out of driving it a lot.


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## jgotzens (Jul 15, 2014)

Been reading this thread and still a little confused. First, my 66 GTO is a 389 Tri Power with 670 heads. Right now running 93 octane (highest around other than 100 race or without an additive.) It runs good and I don't hear any detonation. But after reading GEETEEOHGUY's story maybe I'm just not hearing it. I have a drop top and it's down all the time so who knows. My flowmasters could be drowning it out. I know 670's need special attention to run on a 389 and they seem to have the right cam/piston set up since it all runs good. I haven't checked the timing myself, but the guy place I bought it from said it was close to 9 degrees rather than 6. It idles fine but does "clunk" a little when I put the His/hers shifter into t gear so it's probably can be backed down some. With all that said, I'm wondering even if everything "seems "OK" I shouldn't go to 100 octane or an additive to 93 just to be safe.


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## geeteeohguy (Feb 2, 2008)

jgotzens, I answered your PM. In addition, you can periodically pull the spark plugs and check for aluminum on the center insulator. Microscopic bits of aluminum are piston particles, and means you are pinging away! Lower the top or open up the window and drive along side a sound wall, guard rail, or tunnel wall, and roll into it on a hot day with a warm engine. You should be able to hear it rattle if it's going to.


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## 666bbl (Apr 13, 2014)

3 pages and no mention of E85, so I have to ask about availability to those in the topic. I can get it at a place about 9 miles away which is the closest. I see it at almost every station along the turnpike and the rest of I-80 in PA on my annual pilgrimage to Hershey. No love for E85 at 100-105 octane? Not worth the mechanical up grades?


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## geeteeohguy (Feb 2, 2008)

Not available here. Had a friend run his '67 GTO on alcohol back in the late '70's when in college. He simply took the jets out of his Q-jet and went at it. Said it ran super cool, and produced great power. Went from 15 mpg on gasoline to about 6mpg on alcohol. No corrosion issues, don't know how he got around that, but it was in Arizona. E85 would be attractive if it were more widely available, though. Even with half of the energy gasoline has.


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## 666bbl (Apr 13, 2014)

I don't know that it's 1/2 the energy but the BTU factor is indeed less. I'm not there on my project yet but I fully intend to exploit the performance and detonation safety of E85 when I am. I'm still looking for that story about the 57 Ford Power Tour car. As I recall it was one bad mutha of a street car.


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## Goat Roper (Oct 28, 2014)

My '67 knocks hard on the 91 we get out here in Ca. and the engine is very tired.
I pulled it and tore it down yesterday, it had 6-8lbs oil pressure down from 55 when cold @ idle.
The cam bearings were galled but the bores were shiny but clean and measured 4.120
So original engine that has never been bored.
The oil pick up was filled with remnants of the plastic teeth off of the original timing gear and chunks of metal from the cam bearings.

Going to pallet the block, crank and heads today and ship it off to Jim @ CVMS in Virginia for a low compression rebuild so it will run on this crappy gas we get out here in Ca.
I played with octane boosters and the local parts store carries Sunoco 100 but 67 bucks for 5 gallons isn't going to work for me.
I was heading for a rod out the side of the block so better to just pull it before I grenaded the block.
The rest of the car is done so once I install the engine all that is left to do is drive it.


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## geeteeohguy (Feb 2, 2008)

Very smart move, GR. You'll get back your original engine and it'll be powerful and bulletproof.....and you'll be able to run it all day long on pump gas to enjoy your car. Dropping the compression on my own '67 a few years ago was the best thing I ever did for the car. I drive the wheels off of it now, and don't need to mess around with additives, retarded timing, water injection, etc. etc. Just fill up the tank and go!!


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## geeteeohguy (Feb 2, 2008)

Oh, another thing: be sure to tell Jim that the guys on this forum recommended you!! Can't hurt anything.....he used to post here himself as "MrPbody".


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## Goat Roper (Oct 28, 2014)

geeteeohguy said:


> Oh, another thing: be sure to tell Jim that the guys on this forum recommended you!! Can't hurt anything.....he used to post here himself as "MrPbody".


I already told him he came highly recommended from the members here and he grew up and went to HS in Berdoo and knows this area well.
He remembers Sig Nelson and when Mission Pontiac was still open.
Sig is gone along with Speed Donaldson and anyone in So Cal I would trust with this engine so it is worth the shipping to get er done right.
Engine will be on it's way on Tues. and I just had the car flatbedded from my buddy's shop to my garage for it's winter nap.
Now I can detail the engine compartment, replace the rag joint and a few more details.
Up here they use salt and cinders so I gimped it around town until the first snow so I could get the engine done during the winter and be ready to roll in the spring.


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