ignition timing and fuel

[Jimbo]

hi everyone
question about timing, mine is currently set to run on standard 95 ron fuel on standard 260z 1978 engine
however with all the fuel going e10 im going to start using super but will i need to advance the timing or can i leave it alone?
many thanks
james

 

[TimFZ]

If you have previously used 95 ron in E5 form, then using 97 to 99 super in E5 form won't require any adjustments. In fact if you wish you can advance a couple of degrees for more power potential.

If moving to E10 you may need to slightly richen your mixture, from 14.7:1 to 14:1 to make up for the increased oxygen in the fuel.

 

[Jimbo]

many thanks timfz im going from e5 unleaded to e5 super
so leaving the timing as is wont cause any harm? i can advance the timing but didnt know by how much
i do have a timing light so can do it but would rather leave it well alone if i can as it runs sweet as is

 

[TimFZ]

many thanks timfz im going from e5 unleaded to e5 super
so leaving the timing as is wont cause any harm? i can advance the timing but didnt know by how much
i do have a timing light so can do it but would rather leave it well alone if i can as it runs sweet as is

I would leave it alone. The extra octane just makes it more knock resistant so better. Great if you have a high compression engine but no adjustments necessary. I use Esso 99+ supreme which at present in most of the UK is completely ethanol free but still marked as E5 (ie up to 5% ethanol but in most cases only traces). On this, it runs really sweet and its also best to use ethanol free for layup time.