Fuel for unconverted TR3A

[Neil]

I have heard it said that Shell Optimax (with additive) is best for classics that haven't been converted for unleaded fuel. My car hasn't been converted and I put any unleaded in it (with additive).

 

Has anyone any experience of Optimax? does anyone know if it does make a difference? Is it worth the extra money?

 

I'd like to hear any views ...

 

TIA

Neil

[jonlar]

Hi Neil, most in here recommend it's worth using (haven't tried it yet personally but will eventually) especially if you have any problems with pinking or running on.

 

I've used Castol Valvemaster Plus (phosphate additive) which is available from Halfords (is Halfords part of the Castrol group - I'm sure they were) claimed to raise octane rating and protect valves.   Once this bottle is used, I'll be going over to Tetraboost, but must be handled with care as it contains real lead.

 

http://www.tetraboost.co.uk/

 

I'd suggest you check your valve clearances every few thousand, just to check there is no recession and closing up.

[Don Elliott]

I rebuilt my engine in 1988 and then Canada announced that leaded would no longer be available after January 1, 1990.  I had done the head as one would for leaded.  So when the TR was back on the road in 1990, I wanted to see how long I could run it before having to put in the inserts for the exhaust valves to accept un-leaded.

 

I always tried to use Shell Formula as it was called here in Canada.  Shell said it had a Manganese additive to replace the lead for cars not yet converted.  But the additive was a benefit to only about 0.1% of their customers who owned older cars.  Also the additive fouled the sensors on the new computer controlled cars.  So in 1993, Shell stopped putting in the additive.

 

By this time I had driven about 23,000 miles.  I had never used any substitute additive.

 

So I continued with the experiment.  Between 30,000 miles and 43,000 miles from the rebuild, I had to check the valve clearances more frequently as the unleaded was getting to cause the vlaves and seats to be eaten away.  I was gapping them about every 3000 miles when the exhaust valve gaps were at 0.002" instead of the usual 0.012" where I had set them.

 

As Jonlar says, you have to check them more often.

 

At 43,000 miles I removed the head and had it converted for unleaded.  Eight new valve guides and valves plus 4 steel inserts for the exhaust valves.  The old valves were razor sharp on the edges and very thin.  I could see the recession step in the seats area around the exhaust valves.

 

So the answer in my case was about 43,000 miles before it had to be done, providing everything is 100% before you start.

 

Since then, I have driven 40,000 miles and while I still check the clearances every 5000 miles, I have not had any change in the gaps and I have not had to regap the valves since the conversion was done.

 

Don Elliott, Original Owner, 1958 TR3A, Montreal, Canada

http://www.zen21606.zen.co.uk/Forum%20Gallery/don3a2_big.jpg

[Mychael]

I use optimax here in Australia. The octane rating of our fuels as I understand it is not as high as in Europe.

The car runs fine with optimax and valvesaver additive but was a bit prone to fouling the plugs when idleing, this resolved with the fitting of electronic ignition.

The optimax did nothing to alleviate the running on I get and the car will run ok on regular grade unleaded but seems to run a bit hotter so I try for optimax when I can.

 

Mychael

[Robin Powell]

I always use Optimax on both the TR3A & TR4A neither of which have been converted and add TetraBoost lead additive which makes leaded 98/99 octane petrol that the cars were designed to run with. I get no running on and the cars run much smoother than with lower octane.

[tony13579]

I noticed that tesco in Southampton removed LRP from its pumps this week claiming that it was no longer available in this region!

any one know any more?

[jean]

On the Euro Continent we still have grade 98 at most pumps, in addition to the 95.

I noticed on my TR3A that run-on only occurs when idling speed is above 1k rpm. The engine is tuned to operate on Webers and with the actual SUs I have to keep it on a rather high idle to run smooth.

So before switching off I give a pull on the accelerator pedal to decrease the idle, as soon as it reaches 800 rpm no problem with run-on anymore.

Jean