Ignition Timing for 95 Octane

[spitfire newbie]

Hi all,

I recently invested in a Mk3 Spitfire and am in the process of tuning up.  Unfortunately the only fuel I can get locally is standard 95 octane unleaded.  Although the stated ignition timing for 97 octane is 6 degrees BTDC, I have read that running with these settings for any length of time using 95 octane can damage the engine.

Does anyone know what the timing should be set to or is it just a case of trial and error until pinking is eliminated?  

Alternatively, is it better just to use additive and sod the expense?

Any advice appreciated!

[Deleted User]

Keep tweaking the timing until you get rid of the pinking (a little pinking under hard acceleration at low speed in a high gear up hill is OK) - the distributors are now so old and worn you will never get an accurate setting.

Has the engine been converted to run on unleaded ?
If yes, no problem,
If no, how do you intend to use the car ?
If it's going to be regular/occasional short distance stuff,  then just run it on unleaded and keep a close eye on the valve clearances and when it becomes obvious that there is a seat recession problem, get the head converted - this could be anything from 10,000 miles upwards before it even becomes noticeable.  The effect is called "lead memory" - do a search if you want more info.
If it's going to be long distance, high speed stuff, then consider getting the head converted.

[Clive]

Agree with kevin. Dont worry about figures, eliminate pinking and its about right. If you can get some new advance springs for the distributer so much the better!!
And I ran my vitesse on unleaded for 30000+miles with no additive. It had tyhe valves reground and only 3-4000miles of "leaded"use prior to this, so little lead memory.
When I finally stripped the engine the valve seats had no wear at all, and that car was thrashed.

[spitfire newbie]

Many thanks for that.

I don't plan to use the spit for heavy and hard use so I'm satisfied that I should be OK to run on unleaded.  It's a 1968 car with 47,000 miles on the clock, and I'm sure the valves should be seated OK.  I'll keep an eye on things all the same!

If the bodywork is anything to go by it has been well looked after and has obviously been somebody's baby, so I don't think it will have been driven to destruction either!

Thanks for the advice re. tweaking until pinking is eliminated - I'll give it a go.

Happy motoring!!