Donnington Track Fun, Until Engine Died - Help Appreciated!

[PerthRS]

To save yourself working under assumptions. I'd still check the timing (confirm if valves are bent) for process of elimination.

Unless the garage already checked that before directing towards fueling components?

If you don't have a crank locking pin. Remove cyl 1 (gearbox end) sparkplug and rest a screwdriver on the pistons crown. Manually wrench the crank until it's at TDC. Then remove the rubber cam caps. Inspect the cams. You should see both cam timing tool slots inline with each other. Smaller crescent towards the bottom.
If this is what you see. The timing is not your concern.
View attachment 1766951

If it isn't the above.
Don't see it often, but my old 182 had starting/spluttering issues. Ended up being a faulty throttlebody.
Doing a quick swap would confirm if it's this.

 

[Flob]

Check everything tbh, I've not seen a bent valve with compression, bent valves for me have always = no compression however checking cam timing should be very high up on the list of things to do.