What's the best fuel?
 

I just got a 1979 Leyland Mini and I don't even know what the best fuel to run in it is. It's a 998cc engine and I want to make sure that I'm running the best fuel in it. Any help would be great.

Also does anyone know where I can get an owners manual for it?

Manual link here: http://www.gbcarparts.com/proddetail...d=ManualHaynes

I use only the highest octane in my 1275cc

edit: I just noticed that GB Cars is out of stock. You can email him or look for another one.

I use regular in my 998cc but I've heard you should run the high octane stuff but mine runs fine with the regular stuff.

Fuel
 

I tried mid-grade in my 1275 once - car bucked and backfired.....back to hi-test since. Now that said, this is the way my car is tuned.....since we're talking 'old' engines here much of this can be adjusted via timing, plugs and carb needle.

A source for the owners manual and other original documentation is the CD from Heritage (available from MiniMania and others) but note that this disk is not currently compatable with VISTA or MAC. It runs fine on XP systems. The authoring company has been non-responsive to questions about upgrades altho Heritage' website says "on the way...."

The manual for 1976 to 1980 850 & 1000 says on page 12:

"Choice of fuel The engine of your car is designed to use fuel having an octane rating of 90 (RON) which is within the 2 star UK rating band."

Note also that UK RON is not the same rating system as the US....close but different....see http://en.wikipedia.org/wiki/Octane_...rement_methods
or others

Thanks!
 

Thanks everyone for all the information. You guys are the best!

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Here is a picture of me with Sasha on the trailer.

https://www.northamericanmotoring.co...m/IMG_3057.jpg

Nice photo, thanks for sharing!!!

Very nice, congratulations!

congras on the mini. she's a cutie

I have to hold back from just spending lots on her... There are so many things I want to do to her. I just want wait to get home every afternoon and just do stuff and ride around... I'm smitten.

what a beaut! funny thing is, i was thinking about this allll day and was about to start a thread on it!

I'm glad I started this one because it is very important.

One question that hasn't been asked yet. Has your car been prepped to run on unleaded? Otherwise, in addition to the suggestions regarding octane ratings, you'll also need to run a lead additive.

Do they even sell leaded gas anymore? buy an unleaded head, saves you trouble in the future.

I run my Mini on mid-grade which is 89 octane in Vegas. It is quite happy on it and passed the smog check no worries. I tried with the cheap stuff and he was all sorts of upset.

The car has been prepped to run on unleaded. What kind of additive should I use?

I don't use any additives in mine. You can try the cheap stuff but if it kicks and spurts when you turn it off, put in the higher octane. Mine will run on for a few seconds with the low grade stuff. Only high octane here.

No additives are needed if its been prepped to run on unleaded fuels. I say buy the highest octane fuel you can afford to buy, but midgrade should be sufficient unless you can feel or hear it pinging under heavy loads or steep inclines then go higher in octane.

I use the highest I can find... I'd rather spend the money. Thanks for all the help.

Octane means?
 

Is it useful to discuss Octane and what it means for a minute?

http://auto.howstuffworks.com/question90.htm

"If your engine knocks, use higher octane...."

Our engines suck in a cylinder of fuel and air, then compress it, then blow it up, to produce the power that makes the wheels go round and round. When you compress the fuel/air mixture it can and will explode purely from the compression if u compress it enuf.....that's how a diesel engine works (no spark plug). 'Enuf' "depends" .... In a gas' engine we don't want spontanious combustion, we want it to blow at a specific time, when the spark plug provides the spark. When the explosion happens before the spark (which should happen at a specific place in the 'stroke' but let's not go there) .... you get 'knock'. Knock is bad. Maybe you don't knock around town, but stomp the gas....run up a long hill, you put more load on the engine and the 'back pressure' runs compression up....knock....knock is bad...we don't want knock....:nod:

Octane Rating is a measure of the resistance of the fuel to ignition. In a high compression engine you need higher octane to prevent the 'blow' until the right time..u wnat to b able to achieve more compression b4 it blows. You want it to be stable until the spark. Older Mini engines (if in decent shape) run at higher compression than is common today (a 'legal' import is 25 years old, right?). Which is why our 'average' gas, at lower octane for today's lower average compression, will blow up too early. (and why an engine with a "blower", turbo'c or super'c who's purpose is to compress the fuel/air mix, needs octane)

In the US, the major environmental concerns on engines - cat' convertors - and the like happened in the late 70's (UK followed along later...). As US companies put all the 'pollution crap' on the engines, and lowered the average compression ratios, those of us with strong and somewhat older cars were in a bind. We needed higher octane but couldn't get it......a 'trick' was to retart your timing a couple of degrees. (Two degrees additional before TDC on my 75 Cutlass/350cuin/4 barrel was good) Not really a good solution overall.....but by telling the engine to 'blow it' b4 it went off from compression and THEN having the spark you could get rid of the 'knock', Hence my earlier comment about engine tuning...

You can retart timing, or play with fuel mix to deal with the complex equation of when the fuel blows up. An older 'loose' engine may have poor compression.....and a rebuilt engine using performance parts may have compression beyond stock (see comments about oil relief valves for engines with too much oil pressure)

Why did I bother to post this? I think that once you understand the mechanics and physics you'll realize that what's in a 25 year old owner's manual, and what each of us experience in our car is a starting point....many of us "don't know what we got" anyway! If the previous owner set up the ignition and carb to run on 80 octane it will run GREAT on 80 octane....the HP output won't be up to specs but that may not have been the goal.

As I see it, here's the deal: We can agree that 'knock' aka pre-ignition is bad. One factor you can adjust is octane. It is probably the easiest factor to change. I can't find a reference that suggests running too HIGH of an octane is going to hurt anything....as long as we stay with gas!

So drop your octane if you want.....if the engine complains, go back up....

In Europe there is only 95 octane.

Our BEST is not as good as their normal gas.

High octane is all I use in EVERYTHNG.