Static timing for current fuels

[KM]

I have a Tr4a which I set the timing at 4 degrees BTDC as the static timing and then advance it slightly after a few drives. No science involved. Is there a recognised static timing advance for 99 or 97 (or even 95 when desperate) octane fuels? If not how should the correct timing be arrived at. My crank pulley has a nick to show TDC but nothing else in terms of angle marks.

[thescrapman]

Find a flat piece of road, 4th gear at 30 mph and floor accelerator. It should pink momentarily and then no more. Keep advancing timing a bit at a time until you achieve the above.

 

[KM]

Just to clarify, when you say the above do you mean when it starts to pink?

[glang]

Yes the optimum end result is that it pinks momentarily then stops. I set my Vitesse so that the pinking stops when I hit 2000rpm on the flat accelerating hard in 4th but essentially it's the same thing. Normally however you set the timing to the manual setting (this was for old 5 star) then retard timing until you get the correct amount of pinking described. There's no point advancing the timing beyond manual setting whatever pinking you get and don't forget weak fuel mixture or a worn dizzy can also influence pinking

[RobPearce]

Yes, advance until it pinks just a little and then stops as you accelerate. These old engines are quite tolerant of a little bit of pinking but you don't want too much.

[KM]

And so I get there in as few iterations as possible what additional advance is likely? Less than 5 degrees? More?

Thanks in advance.

[thescrapman]

Not sure what you mean Kevin. 

You should not end up with more advance than the original factory setting, unless something has been changed from standard.

 

[glang]

I think Kevin wants to do it his own way

[KM]

Have settled on 7 degrees, mostly 97RON.

[KM]

Quoted from thescrapman-

Not sure what you mean Kevin. 

You should not end up with more advance than the original factory setting, unless something has been changed from standard.

 

Colin, I have a 4:2:1 exhaust but no other performance changes. Are you saying the timing should be retarded from the factory 4 degrees?