Is all your tinware present? Mine was getting that high on hot days looked over the engine when I was changing my clutch and found I was missing four pieces.
I would supect something wrong if it does this at 50 mph. 130 degrees at 75mph on a hot day you might just be being cruel to your engine. Dont drive it like that or things will age rapidly - cylinder head cracks , bearings may wear faster. That would either be lean jetting or a stuck thermostat rod causing the flaps to stay shut or the airflow round the engine is wrong due to tinware missing or too much foam from the engine bay seal wrapped round the cylinders or rags in the fan...
will have to give it a run tonight but it defiantly hit that temperature at one point, would too much oil cause it to over heat? @zed @mikedjames @snotty
By changing the jets. Did I read you have 125 mains? Do this - start it up and warm it up. increase the revs until you're at full speed. If it farts and pops your mains are too small and it'll get very hot even at the lower non-farting revs. Your new engine will run hot though until the rings have bedded in. I would advise keeping journeys to 20-30 miles then full cool down for the first couple of hundred miles.
@zed, as it stands she doesnt pop or bang through the gear ranges at all, i think i have a little to much oil and i have smacked that temp sending dip stick a few times so its accuracy is questionable. going to make further investigations tonight though. perhaps a sump plate temp sender is better?
It might cause you to suck in hot exhaust air into the engine compartment... but I would have thought this unlikely when you're rattling along...
Probably doesn't make that much difference but it's there for a reason so you might as well bung one on.
I think i need to add that, drop out a bit of oil, then take her for a spin and see whats being read. its the firs time shes been driven after about 4 months also.
The dipstick sender seems pretty accurate after mistreatment - I have bent mine and kinked it, trapping it between the tinware and the body, and it still reads OK. The more oil you have the "cooler" it runs as there is more oil to heat up, which on a shorter journey means it stays cooler - it was one way I used to tell that the oil on my old leaky engine was near minimum was noticing the temperature would creep up a bit. It may be worth doing the plug colour test to look up how lean it is running.
