How do you advance the timing on a fixed endbell motor? is it possible?

I think the purpose of a fixed endbell is that timing changes are not alowed.......
Most simple way is an adjustment in the ESC.

But if it is just a motor you want to use then get an optional endbell to set the timing or with some motors you can get optional sensor plates with different timings.

And if you want to play dirty you have to be an expert in SMD soldering.

fixed end bell.. to keep the playing field even.. ( so they say.).

most racing leagues ,,, altering the timing is NOT LEGAL.. and the reason for FIXED ...

or learn, machining .. motor design, electronic motor control...

or purchase a new adjustable timing motor...

No, I would blatenly like to cheat. Everyone else is,so I would like to also!

have at it...

I do not cheat... no need to.. 28 years of rc racing...... yes 1991...
I pick my line,,, I drive my line... and finish the best I can... on dirt.

Yesterdays race.... of the 5 minute race.. I turned 5 laps of 50 seconds and one of 52 seconds.. finished third... 10 car heat.
I never touched another truck.. an not one board..

most of the trucks run 6.5 to 8.5 motors.. I run a 10.5... on dirt its not possible to use all the power.
and yes.. we have a LARGE race track. the 17.5 stock class average 60 to 66 seconds per lap

​​​Very likely not the case.

Straight line speed is based off corner speed. You are getting passed on the straights because they slowed down less for the corner before the straight. Getting through a corner as quickly as possible is a skill you need to improve. You need a well built, well set up car on the right tires to be able to maximize corner speed. A few more degrees of motor timing won't make up for inability to take a corner as fast as possible.

You can cheat, but you lack the driving ability to take advantage of the power gain you would get by changing the timing. Does this class have a gear ratio limit too?

If you want to change the sensor timing you can do it in many ways, you only need to shift the sensors a bit but think of what can happen if you get caught. Sensor timing is easy to measure with a motor analyzer and any mods to stretch up the position of the sensorplate will be noticed with an inspection so any degree too much and you are sended home.
Although some people are optimizing the motor sensor positions to get them as equal as they can what does improve some performance in a more balanced rotation but only noticeable to those who are on the limit. Several tutorial about this can be found on the web and on these forums.

But there is a book you can buy called "speed secrets", its all about getting the maximum out of RC car driving.

the timing changes the powerband a simple gear change can fix the speed issue, no need to cheat