What octane fuel?

[fireguy514]

Hi all,
I have a '65 Fury III with a 383 V8 Commando engine. I'm wondering what type of octane fuel you all put in your classic cars. 93 octane or 100 octane racing fuel?

 

[Davea Lux]

Hi all,
I have a '65 Fury III with a 383 V8 Commando engine. I'm wondering what type of octane fuel you all put in your classic cars. 93 octane or 100 octane racing fuel?

I run the "real gas", moonshine free premium. Has sufficient octane for a performance engine and does not leave any nasty carb residue if the car sits for extended periods of time.

Dave

 

[CBODY67]

"93 Pump Octane" is about "97 Research Octane", which is what Premium was in 1958. Issues can be "no lead" and "Ethanol". Even "race gas" can have ethanol in it, too. Some are still available with lead, too. Read their information sheet for these things.

CBODY67

 

[71Polara383]

I run 87 in my old cars. Alot of folks swear you gotta use 93. Pretty sure they are wasting money. But that's their preference and their money so it's not my problem.

If you don't have high compression where you will ping with lower octane fuel its gonna be just fine. If you can find ethanol free 90, that'd probably be the best thing. I normally don't even bother unless I feel like splurging a little.

I'm sure someone's gonna come spewing their crap about why you MUST run 93...I've been daily driving old mopars on modern-day 87 for more than a decade and haven't had a single issue.

 

[darth_linux]

I run 91 ethanol-free with my 66 383 2V. No issues at all.

 

[Big_John]

Hi all,
I have a '65 Fury III with a 383 V8 Commando engine. I'm wondering what type of octane fuel you all put in your classic cars. 93 octane or 100 octane racing fuel?

Unless you've done something to raise the compression ratio, the 100 octane racing fuel isn't needed.

Myself, I run 91 octane ethanol free gas. That seems to work well for my cars. Since I'm in the Finger Lakes, and boating is big here, the ethanol free gas is easy to get and not too crazy for cost.

IMHO, you are better off running the ethanol free gas, but sometimes it's tough to find. I also think that a lot of the horror stories of ethanol laced gas are exaggerated, but that's another discussion.

If ethanol free isn't easily available, I would suggest starting out with the 93 octane and see how it runs. I'm assuming this car is new to you by this question. Once you've got a few miles under your belt, and know how the car behaves, try running some 87 octane if you'd like to. If the car pings excessively, run the 93.

Too much octane won't hurt, but at the same time, it doesn't buy you anything if you don't need it.

Some guys will also mix a little 2 cycle oil in their ethanol mixed gas. @Ripinator and @detmatt have been using it for a while and can elaborate more on it than I can.

 

[CBODY67]

Back in the later 1960s, I noticed what grade of fuel people bought for their cars back then. It was unusual to see a Cadillac owner who bought Premium fuel, opting for Regular instead. Yet the engines were 10.0CR. They claimed "no clattering", which I found hard to believe, but that was their consistent story of the several that I gently inquired about. By the same token, ALL Lincoln owners said "Fill it up with Premium" and didn't bat an eye.

From the time we bought our '66 Newport 383 2bbl with 7100 miles on it, when the '67s came out, it never liked Regular, so we just upgraded to Premium. Of course if you drove a Chrysler, you should be able to afford the higher cost fuel, if needed, back then. Kind of an additional status symbol . . . which also allowed me to tweak the timing up a bit to 15 degrees BTDC (from 12).

In many cases, people never got past 1/2 throttle very much, so lesser octane tended to work for them, then as now. Whatever works!

Current Pump Octane "+ 4" usually, roughly, equates to the old Research Octane numbers quoted in the owners/service manuals back then, pre-1973. Regular was 94-95 Research Octane and Premium was 97+ Research Octane. Sub-Regular (as Gulf Gulftane was) was about 91 Research Octane. The original Low-Lead and Unleaded fuels were 91 Research Octane, now 87 Pump Octane. What I observed happening "back then in real time".

What ever works!
CBODY67

 

[commando1]

I run the lowest octane possible without pinging under hard acceleration.
The lowest octane possible is dependent upon your timing,
9 times out 10, our cars need premium to achieve this. I found this true even on a '76 440 with a CR as low as you can go.
Ethanol? Life is short. I have better things to do than chasing around looking for it.
Most of us don't drive our cars enough where ethanol is going to hurt you.
I think this whole ethanol thing is the biggest scam to come out of Washington, second only to vaccine shots.

 

[Ripinator]

Unless you've done something to raise the compression ratio, the 100 octane racing fuel isn't needed.

Myself, I run 91 octane ethanol free gas. That seems to work well for my cars. Since I'm in the Finger Lakes, and boating is big here, the ethanol free gas is easy to get and not too crazy for cost.

IMHO, you are better off running the ethanol free gas, but sometimes it's tough to find. I also think that a lot of the horror stories of ethanol laced gas are exaggerated, but that's another discussion.

If ethanol free isn't easily available, I would suggest starting out with the 93 octane and see how it runs. I'm assuming this car is new to you by this question. Once you've got a few miles under your belt, and know how the car behaves, try running some 87 octane if you'd like to. If the car pings excessively, run the 93.

Too much octane won't hurt, but at the same time, it doesn't buy you anything if you don't need it.

Some guys will also mix a little 2 cycle oil in their ethanol mixed gas. @Ripinator and @detmatt have been using it for a while and can elaborate more on it than I can.

Yes. I run one ounce of marine two-cycle oil per five gallons of gas in all my vehicles - old and new. The two cycle oil does not add anything that would impact octane rating, but it does help keep intake valves and plugs clean. It also provides extra lubrication to electric fuel pumps and lubricates the pistons ring pack, thereby improving combustion. I find that the engine just runs better when I use the two-cycle oil; there is also a slight improvement (two to five) in mpg. The two-cycle oil I use is from Wally World - their brand. I buy it by the gallon for about $18.00.

Regarding octane rating and the fuel you should use: Two of my cars have TNT engines with 10:1 compression ratios. I run 93 octane in them. My '73 Chrysler Navajo has the low compression 400 cu. in engine; in that car I run 89 octane. In addition to the foregoing, I also set timing to spec in my cars and then reset the timing by ear. I drive the car and gradually advance the timing until I hear the engine ping; then I gradually back it off until the ping goes away. Viola!

 

[MoPar~Man]

There are people that swear by adding oil to ethanol-gasoline. There is mention of something called tcw3 (ashless 2-cycle oil) and mmo (marvel mystery oil). At a mixing ratio of 400:1 to 600:1. I guess that's 2 to 4 oz per 10 gallons. Some claim smoother idle.

https://bobistheoilguy.com/forums/threads/luvin-the-tcw3.113639/#post-1573591

 

[Ripinator]

There are people that swear by adding oil to ethanol-gasoline. There is mention of something called tcw3 (ashless 2-cycle oil) and mmo (marvel mystery oil). At a mixing ratio of 400:1 to 600:1. I guess that's 2 to 4 oz per 10 gallons. Some claim smoother idle.

http://[URL]https://bobistheoilguy.com/forums/threads/luvin-the-tcw3.113639/#post-1573591

[/URL]

Yes. I should have noted that the marine two-cycle oil to use should have the TC-W3 additive package. Again - use one ounce per five gallons.

You could use Marvel Mystery Oil, but it would be very expensive as compared with the marine oil from WalMart.

 

[mrfury68]

I run 93 0ctane premium in my "G" code 383 2 bbl. for a few reasons: It pings on 87 octane and even mid grade 89, but not on premium. Timing is set with a light and vacuum gauge and the driveability is second to none. Premium grade fuel has the least amount of ethanol than the lower grades. Ethanol free gas around here is around $5 per gallon if you can find it. I also put in a can of Sea Foam in the tank for winter storage. Every so often I will run a bottle of Marvel Mystery Oil through the tank. As they say, "your mileage may vary." Find what works best for you and your ride and run with it.

 

[Just Carbs]

I have a 64 New Yorker with a 60k mile 10 to 1 (says Chrysler) four barrel 413, timing at 10 BTDC per Chrysler. Vacuum and centrifugal advance appear to be relatively correct.
It doesn't like non ethanol 91, "very" slight audible ping.
No audible ping with 93 ethanol.
I'll try 91 non ethanol at 6/8 BTDC and see what happens.
I add 1-ounce TC-W3 oil to 5/10 gallons of gas to prevent tank corrosion.

 

[carguy300]

I know in texas a lot more places are carrying non ethanol fuel, mostly 90 oct. Ran it in my last 300. Didnt have any issues with it, was only few cents higher. Was a buckees just a few miles away. Plan on running it in this 300,.. as soon as its running!

 

[Snotty]

I run the highest grade I can get. If it pings I add a bottle of Octane Booster.

 

[SuperDave]

90 or 91 octane ethanol free here in NE Texas. I won't run corn gas in my hotrod '73 Newport if I can help it. Always with Pro-Long fuel stabilizer, as it may sit for weeks or even months at a time. Lots of boaters out here in my neck of the woods so real gas is plentiful.

400 motor isn't stock, only the block, oil pan and crank are original. Flat top pistons, shaved 440 motorhome heads, 4 bbl Eddy, cloned "purple" cam, headers. Compression works out about 9.6:1. I COULD run 87 and retune it but then it runs like a dog. Right now I tune it by ear & the seat of my pants.

My '02 Ram runs 87, with a bottle of STP fuel treatment in every tank. It's fuel injected & has O2 & a knock sensor so it can self tune on the fly. It's my daily driver, Project Turd is my weekend warrior.

 

[Reliabilityman]

Whatever you do if the car sits a lot and has non-ethanal rubber treated lines/carb gaskets etc. Do yourself a favor and only by "non-ethanol" premium. While more pricey up front will save you a lot of headaches in the future........well worth that.

 

[guss]

I run 93 0ctane premium in my "G" code 383 2 bbl. for a few reasons: It pings on 87 octane and even mid grade 89, but not on premium. Timing is set with a light and vacuum gauge and the driveability is second to none. Premium grade fuel has the least amount of ethanol than the lower grades. Ethanol free gas around here is around $5 per gallon if you can find it. I also put in a can of Sea Foam in the tank for winter storage. Every so often I will run a bottle of Marvel Mystery Oil through the tank. As they say, "your mileage may vary." Find what works best for you and your ride and run with it.

Talk to the fuel supplier. The higher the octane the more ethanol in the gas. That’s how they raise the octane level in unleaded gas.

 

[notsosan]

Hi all,
I have a '65 Fury III with a 383 V8 Commando engine. I'm wondering what type of octane fuel you all put in your classic cars. 93 octane or 100 octane racing fuel?

I run 91 ethanol free in my 66 440 TNT. Runs fine. Some guys will only use 93 or 94 but I haven't found it necessary.

 

[NitrousTuner1]

Hi all,
I have a '65 Fury III with a 383 V8 Commando engine. I'm wondering what type of octane fuel you all put in your classic cars. 93 octane or 100 octane racing fuel?

91 or 93 is fine. The to engine life & exhaust valve seats is lubricant.
Since the lead is missing you want to Add
TCW-3 2-stroke oil to the dry fuel of today.
The best place to start is 4gal of gas to 1 Oz of oil...
It's a well known secret that was figured out about 15-16 year's ago. It even helps greatly with diesels. I travel alot for my tuning. And even the brand new rentals car's I use will gain 1-2mpg's by adding the TCW-3.
The other HUGE improvement that should be made is make sure that the vacuum advance is hooked up to Idle/Manifold vacuum & Not ported. You want the vacuum advance to work at idle/high vacuum NOT stepping on top of the mechanical advance in the distributor.
That way you can keep it up around 34° All the time