Petrol, Optimax or Additives?

[jedo]

Hi,
I have just bought a 1972 1850 Dolly. I've started running the car on Shell Optimax for the higher octane, but do i need to put lead additives in aswell or any further octane boost?
What does anyone recommend?
Thanks James

[Howard81]

I've always ran regular unleaded with Castrol Valvemaster additive. Haven't noticed any difference between regular Valvemaster and Valvemaster Plus though!

[jedo]

Thanks, i'll look into them!!

[bifold]

I am running on optimax ,and the 1850 dont need no lead,

[JPB]

Shell V-Power and, as Mike (BiFold) said, the engine is metallurgically suited to petrol without added lead, so it doesn't get additives. Mine's just as happy on supermarket 99RON unleaded from the big Tesco or 97 from Sainsbury. I tried some real 4 star once, just for the hell of it, but it was just a waste of the extra 3p per litre and the base fuel's the same as the premium unleaded in any case, so those fuel pump diaphragms still ought to be the nitrile ones rather than latex.

[Toledo Man]

I use supermarket unleaded (95 RON) with no ill effects and I certainly don't use any additive. The 1850 lump doesn't need it.

[jedo]

Thanks for all these comments, really useful!!

[JPB]

I use supermarket unleaded (95 RON) with no ill effects and I certainly don't use any additive. The 1850 lump doesn't need it.

Unless your timing is set back from 11 to about 8 degrees, you'd definitely get far better MPG figures on 97 or 99.
Mine doesn't pink on 95, even at the 13 degrees that it prefers to run at, but the difference in the consumption actually outweighs the slight extra cost of the higher Octane rating, around here that's currently 95.9 vs 97.9p per litre. Emission figures are greatly improved too; otherwise unaltered, I get 221ppm unburnt HCs on 95, 117ppm on 97 and oddly enough, 181 on 99RON.
Those figures have each been taken as an average, based on 500 Miles of each grade of fuel at a variety of ambient temps and humidity readings, CO was a constant 2.8% throughout.

[jedo]

Can i also just ask do i need any Valve Seat Protection for using unleaded fuel. I know one person has said they use it and another said they don't, does the car actually need this, will it do it damage if i don't use it?

Thanks J

[JPB]

Can i also just ask do i need any Valve Seat Protection for using unleaded fuel. I know one person has said they use it and another said they don't, does the car actually need this, will it do it damage if i don't use it?

Thanks J

No.
The inserts used in any aluminium head must be hard steel or they'd fall out since cast iron doesn't expand anywhere near as much as the surrounding ali, and the valves won't weld themselves to their seats as they're dissimilar. I've raced and hillclimbed any number of Reliant Rebels (Reliant's own all-aluminium "F750" engines) with original heads on, there was a scare during the '90s when some garages were actually charging people for "conversions" but it turned out that the tube stock supplied was exactly the same as the original material. The only thing that may need to be changed would be rubbers such as stem seals, fuel pump diaphragm and carb diaphragms, but even if you were using leaded four star, the current base fuel is the same as the bog stock unleaded and would still burn holes in exposed, latex-based components. Don't let that worry you either, I just had a fresh fuel pump for mine and that has a nitrile diaphragm, Triumph valve guides aren't too sloppy either, so unlike any of my old F750 engines, even running without stem seals wouldn't be the end of the World, the original ones on there are fine though.

Just fill the tank with 97 octane stuff for best efficiency and get out there and enjoy!

My old, Ice blue Dolomite auto last had its head off at 160,000 miles approximately, and that showed no recession, no pocketing and no signs of trouble at all after 70,000 mainly motorway miles on unleaded. When that car came off the road in '95, at 191,000 miles, the engine still had the same valve clearances as it had when purchased by me, at 30,000 miles from new.