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MG MGA - Putting a tiger in the tank

I have the 1800 5-bearing in my MGA. It goes great but has always been subject to ignition run-on and pinking, despite my playing around endlessly with the timing. And yes, I do have very good timing eqipment for setting the dynamic timing.

A month ago I was chatting to my friendly specialist and, without hesitation, he said to put super unleaded fuel (97 octane) in the tank instead of the standard unleaded (95 octane) fuel.

I am now on my second tank of this better fuel (8p a litre more than the standard - currently using Esso but I am told that Shell Optrimax is better and is 98+octane) and I have to admit that the difference is brilliant. Without having touched any carburettor and distributor settings the engine idles 100RPM less, does not pink, does not overrun, runs cooler, accelerates better and generally feels a lot happier.

I am also a lot happier, albeit poorer (89p a litre but it could have gone up again!). Just thought I would share my experience.

Steve

PS. The tiger in the tank was an Esso advertising slogan over here in the 60s/70s.
Steve Gyles

Steve
Good to hear you sorted it out. I always used the higher octaine fuel in my MGB and now use the middle octaine in my 1500 MGA. I am in the process of putting an 1800 3main in my A and will experiment with the different fuels to find the best one. The later MGB engines had an anti run on valve connected to the carbs. I disconected it once and found it made a big difference even with the better fuel when not hooked up I still got some run on.
Kris Sorensen

In Caterham race cars just about all of us use Optimax - not for more power, but because (allegedly) it runs the engine cooler.

And the extra cost is fairly small in the overall scheme of these things!

Geoff

Geoff

It is a colleague of mine who is also a Caterham track day enthusiast who said use Optimax. My initial observations confirm the running cooler bit.

Steve
Steve Gyles

I use nothing but high octane in all my LBCs. None of them like anything less.
Steve Simmons

Steve I think if the car is running as well as you say its probebly doing better milage as well and not costing you any more. Denis
DENIS

I agree that Shell Optimax is by far the best fuel. I run my stage III tuned 1600 MKI and a race tuned 1400cc midget on the stuff.

Here in Germany 100 octane is readily avaiable, which is even better - although somewhat expensive, but the cars do run MUCH better.

Tom Airey (http://www.aireytuning.com)swears by Optimax !!

John
J Harle

I put a tiger in my tank once, the damn thing bit me. They are a protected species now, so dont mess with them
T DRINKWATER

The owner's manual of the 1968 MGB I had, which had the 5-main engine, said to never use less than 98 octane gas. I have a 5-main in my MGA, too, and always use the highest octane. "Put a tiger in your tank" was a big Enco/Esso ad campaign in the States, too, before they combined to Exxon.
They couldn't use the "Esso" name in most of the western US because Standard Oil of California (Chevron) owned the "S.O." (Standard Oil) moniker in this part of the world. Are they still Esso in Europe or did they change to Exxon there, too?
David Breneman

David

Still Esso. One of the bigger names over here.

Steve
Steve Gyles

This thread was discussed between 08/10/2004 and 16/10/2004

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