Anyone here currently running a v12 with additional 5 degree advance (like the AJ6 Andy bracket) ? I'm curious to knkw if it's worth the effort.

 

If that’s all you do, then don’t!!!!
The Jaguar will take additional advance if the fuel is up to it. That’s a great big if. !!!!!
It’s typically not the brand or what you read on the pump. Most stations in a given area are serviced by a refinery. It doesn’t make Economic sense to haul gasoline too far from a refinery. And in spite of marketing to the contrary gasoline is pretty standard. Do you think they have your brand everyplace in the world? Plus the pump listing might be different from what you get. Not by a lot but a little bit. Gasoline that sits in a tank will evaporate some of the lighter ends. If the tank is filled every week or several times a week then no problems. Even several weeks you might be able to get by.

Then again it depends on your driving. If you’re a foot flat to the floor at every light or down the freeway that’s really when extra advance will turn around and bite you. If the fuel isn’t up to it valves get burned and pistons can develop holes in them.

Now we racers always advance the timing. As far as we can. The factory is too conservative and leave power on the table. They don’t want warranty claims.

If you’re willing to risk it, what I do is simply pull the distributor and advance it a tooth. Achieves the same thing. When I’m using E85 I can safely advance it 2 teeth.*

But my race car I’ve put an additional pointer in so I can check the timing as I advance the distributor.

* but I also make the fuel richer. Those two things combined can give me up to 30 extra horsepower.

 

https://www.jaguarforums.com/forum/x...ssible-128515/

 

I have the picture saved of the modded disk to advance it slightly. Bit of effort to do.