Question on gas type from newbie...

[Guest thug23]

I recently bought a 1960 Cadillac and this is my first classic car I've ever owned. My question is, obviously back in the day it would run on regular LEADED gasoline...what kind do I use today? Someone said I can use high test UNLEADED with some kind of lead additive ??? Does this sound right?

Any info please would be greatly appreciated.

[GUS VALERI]

UNLESS YOUR OWNERS MANUAL REQUIRES THE OLD HIGH TEST I THINK YOU COULD RUN REGULAR WITH LEAD ADDITIVE, IF NO KNOCKS.I USE REGULAR WITH ADDITIVES IN MY 48 BUICK SUPER.

[Twitch]

The lead substitude additives are very cheap so you aren't going to go broke using them. I use them in my 50 Packard. Definitely use premium for the octane though.

[ncgirl05]

Okay - one of you said to use regular, the other said use premium..... Is this a personal preference thing?

Right now our cars are in the "working on them" stage so the octane question is relevant for when we get them on the road. I didn't know a lead substitute was needed <img src="http://forums.aaca.org/images/graemlins/blush.gif" alt="" />, nor did I think premium fuel was needed. <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" />

I guess everyone has to be a newbie once in their lives <img src="http://forums.aaca.org/images/graemlins/smirk.gif" alt="" />

[Bob Kinker]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Okay - one of you said to use regular, the other said use premium..... Is this a personal preference thing?

Right now our cars are in the "working on them" stage so the octane question is relevant for when we get them on the road. I didn't know a lead substitute was needed <img src="http://forums.aaca.org/images/graemlins/blush.gif" alt="" />, nor did I think premium fuel was needed. <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" />

Use Premium (high test) unleaded in your Caddy. It has a higher compression engine in it than the above mentioned 48 Buick.

Hope you get the car on the road soon!

I guess everyone has to be a newbie once in their lives <img src="http://forums.aaca.org/images/graemlins/smirk.gif" alt="" /> </div></div>

[Dave@Moon]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> It really depends on what your compression ratio is. </div></div>

The 390 Cadillac used from 1959 to 1963 had a 10.5:1 compression ratio. That's kind of high for today's pump gas, even premium. The Cadillac-LaSalle forum would be a good place to find people who have first hand experience with this motor. You <span style="font-style: italic">may</span> have to go with an octane booster.

[RPrice]

Keep in mind that regular gas in 1960 had an octane rating equivalent to

what premium is today.

My 59 Studebaker Lark is supposed to run on regular, but it pings on today's regular.

When I switched to intermediate grade, it ran fine. The timing checks out

fine.

Rog

[SolidAxle]

Post deleted by SolidAxle

[carbking]

As mentioned by others, the Cadillac engine of this period is probably going to require premium octane fuel, possibly higher. But once you get the vehicle licensed, it is quite easy to determine the answer yourself.

Start with a tank of premium fuel. Now locate a mild hill along an interstate highway where you can maintain a fairly constant speed. With the engine up to normal operating temperature, approach the hill at a speed somewhat below the maximum legal limit. When you have began climbing the hill, attempt to GENTLY accelerate. Listen for ping. If no ping, you can run through this tank full, and then try the next lower grade using the same procedure. The idea is to run on the lowest octane you can with no ping. My personal opinion is that a 1960 Cadillac is going to require at least the highest pump grade available; but don't take my or others opinion. Test and then you know.

Jon.

[R W Burgess]

Jon, this is assuming the timing is correct on the engine in question. Even then, minor pinging can be "adjusted out" by backing the timing up, if you'd prefer to not use the next grade up on your gasoline.

Wayne

[Guest thug23]

Thanks guys for all your advice, I appreciate it. I certainly didn't mean to start any type of fighting among you but it is always great to get everyones opinion.

[Rusty_OToole]

Your octane should look like your compression ratio. My 1951 DeSoto flathead six with 7:1 compression ratio will run fine on 70 octane. My 94 Plymouth minivan has 8.5:1 compression and it takes 87 octane regular. If I had a car with 9.5:1 compression I would buy 92 octane hi test. Naturally you have to make allowances, this is only approximate.

If your Cadillac has 10.5:1 compression it was supposed to get 103 octane Blue Sunoco or the equivalent heavily leaded hi test gas. This stuff has not been available since 1970.

Your best option would be aviation gas from the airport (if they will still sell it to you) or pump hi test with an octane booster additive.

In a pinch it may run OK on pump hi test alone if you back off the timing a bit and baby the gas pedal. But you should use an additive to protect the valves from burning.

[Rusty_OToole]

Incidentally there is nothing to be gained by using higher octane fuel than your car needs. A low compression engine will run better on low octane fuel.

I have heard of some owners of low compression cars and motorcycles who add kerosene to their gas to lower the octane. They report easier starting, smoother running and more power. Also their engines run cooler. These are motors from the teens, 20s and 30s with compression ratios of 4:1 to 6:1.

[ted sweet]

THERE are no octane boosters that actually work, i have tryed them all.

[Guest thug23]

So if there are no octaine boosts that actually work like they are discribed to do...what would you do next? Just use high test unleaded and work on the timing adjustment? I ask because I really don't think I can get aviation gas and I really don't want to mix in kerosene ....my luck I'll blow up the neighborhood. <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

[Rick Hoover]

thug23,

You needn't mix anything in your gas or fool with any timing to compensate. For years, I have reguarly driven and maintained a '59 Eldorado Birritz which has the 390 / 345 hp with 3X2's and I run nothing more than hi-test gasoline in it. Usually Sunoco. So just do that, set your engine to factory tune up specs and enjoy your car.

Rick

[Guest thug23]

Thank you.

[ted sweet]

WHY would you mix in kerosene?

[Guest J446]

Install hardened valve seats and run premium unleaded.

I do this with all my street driven Le Mans cars and they run fine.

[ronbarn]

I have been on many tours with Big Red, my 1961 Cadillac Model 62 convertible. Have always used regular with no additives. I run it often enough to keep track of how the gas is holding up since, as we all know, gas can go bad. For long term storage, av gas is a good idea. The local military museum uses that type of gas since their vehicles set in storage for long periods.

Back many tours ago Howard Scotland was having a recurring vapor lock problem with his '41 Cadillac on hot summer days. Based on another tourists advice he mixed some kerosine (not much) and it seemed to cure the vapor locking. My 1936 John Deere Model B was designed to start (and warm up) on gasoline and then run on kerosine. Since kero is more expensive than gas, I had decided to just run gasoline. A local John Deere collector told me that his multi-fuel tractors run better on a mixture of one part kero to four parts gasoline, so that's what I using now - now it runs like a deere and smells like a john.

[Rusty_OToole]

There are several good brands of octane booster you can buy to RAISE octane.

Some antique car and motorcycle owners add kerosene to LOWER the octane.

Now why would you do that? Because your engine will run best on the octane fuel it was made for. We all know a high compression engine has issues with too low octane fuel, but a low compression engine will run better on low octane fuel than on high octane fuel.

So how do you know what octane you need? The octane of your gas should look like the compression ratio.

If you have 10.5:1, get 105 octane gas. If you have 9:1 get 90 octane gas. If you have 4.5:1 get 45 octane gas.

There have been cars made, and sold for road use, that had compression ratios from 4 or 4.5:1 (Model T, Model A, Rolls Royce Silver Ghost) to 13:1 ( Muscle cars from the 60s like the Max Wedge Dodge 426 and 327 Corvette).

Unfortunately the only gas you can buy today is around 87 (Regular) or 92 (Premium).

So you have to improvise, by buying aviation gas, or octane booster, or using water injection.

Alcohol will also increase octane.

If you want lower octane, kerosene will do the trick. It has the additional advantage of burning slower than gas, which is good for an old time, long stroke, slow revving engine. It helps develop full power all the way thru the power stroke.

Hope this is clear.

[Rusty_OToole]

To answer the original question. If I had an old car like a Cadillac with 10.5:1 compression I would definitely add octane booster or lead substitute to protect my engine and assure smooth running, better performance and protect against overheating.

[ted sweet]

ok, which octane boosters work?

[Rusty_OToole]

Don't know as I never use them. You might try a muscle car bulletin board, they must have tried them all. Or you could try a few different ones and find which works best in your car.

First I would try the car on a tank of hi test and see how it runs. Possibly it won't need anything.

I did have a 68 Buick 430,400HP with 10.5:1 compression. This was in the 70s. It would run OK on hi test, with the timing backed off, as long as you babied the gas pedal. Today I would spend the money on the additive.

[Mike Cullen]

Five or six years ago I had a SBC built to way more than necessary for the street. I was running something on the order of 12:1 CR. In order to run the way it should, I had to mix 2 gal. Leaded racing fuel (110) or 5 gal of AVGAS (101) with every 10 gal. of pump Hi-Test (93) It ran well, but got way too expensive to drive much.

BTW increasing octane slows the burn of the fuel.

[ted sweet]

I have: Thats where the consense that none then work is from.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Don't know as I never use them. You might try a muscle car bulletin board, they must have tried them all. Or you could try a few different ones and find which works best in your car.

First I would try the car on a tank of hi test and see how it runs. Possibly it won't need anything.

I did have a 68 Buick 430,400HP with 10.5:1 compression. This was in the 70s. It would run OK on hi test, with the timing backed off, as long as you babied the gas pedal. Today I would spend the money on the additive. </div></div>

[carbking]

There have been numerous independant tests of the various "octane boosters". All of the tests that I have seen come to the same conclusion; and that is that most of the octane boosters do NOT work and those that do are misleading. The tests indicate when the manufacture advertises that an octane booster will raise the octane 2 points, the manufacture means tenths. So if one had 91 octane fuel, and used a booster that actually did raise the octane; mixing per instructions would raise the octane from 91.0 to 91.2. Thus the booster did work, but will it do one any good? Probably not!

What many octane booster WILL do is destroy any rubber/neopreme in the fuel system to include the rubber cup on most modern accelerator pumps.

As far as the kerosene is concerned: the first time I heard adding kerosene (lots of years ago), I was skeptical that any benefit would accrue. However, I did my homework, and found that kerosene actually contains more energy per unit than gasoline. Thus kerosene CAN be beneficial in older low compression engines IF one supplies sufficient heat to the system to vaporize the kerosene. Without adding sufficient heat, the kerosene would enter the combustion chamber as a liquid, which could cause severe engine damage.

All who are considering the use of alternate fuels should research the amount of heat energy present in the fuel (compared to gasoline). Both heat energy and octane (2 different properties) enter into the amount of power and economy that an engine may provide.

While different labs will derive different actual values depending on the methods used (these differences are quite small) the chart below is typical for heat energy values in BTU/US gallon:

Gasoline 115,000

Gasoline RFG (reformulated) 112,000

Liquid natural gas 75,000

Liquified petroleum gas (propane) 84,000

Ethanol E-100 76,000

Ethanol E-85 82,000

Ethanol E-15 109,000

Kerosene 130,000

So when one sees various alternative fuels at "cheaper" costs than gasoline, one can calulate potential cost savings AFTER the engine is modified to take FULL ADVANTAGE of the fuel. As an example, to maximize power and economy from E-15, the typical engine will require higher compression, more timing, and major carburetor recalibrations (or switch to electronic fuel injection/ignition with fuel sensors to determine the presence and amount of ethanol.

Jon.

[Rusty_OToole]

The kerosene is for very old, long stroke, low compression engines mainly from the teens and 20s. Gas in those days contained a lot of kerosene and car makers went to a lot of trouble to get it to vaporise.