1967 MGB loses power when hot

I have a 1967 MGB that runs great, until it gets warm or if it is particularly hot outside. It will then lose power for several minutes, then it will get better. I can “floor it” and it will only go a few miles per hour. What could be going on?

Could be fuel boiling, or it could be an overheated part of your ignition system. What kind of carb(s) do you have? It could be a weak fuel pump, too.

Have you posted this on an MGB forum?

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Someone knows better than I do, but my hunch is that today’s fuels are a lot more volatile than those of yore.

Good point, hopefully OP is only using ethanol free gas, if not?

Thanks for the suggestions. I will check for phase separation in my gas!

The problem is more that ethanol damages old rubber components in your fuel system.

How much of the car is original? All the rubber components should have been replaced by now, maybe twice.

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If this ancient British car has its original ignition coil (possibly sourced from Lucas…), it is very possible that the coil is the source of the problem.

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edited… the 1967 had SU carburetors and my post referred to Zenith Strombergs.

I’d sure like to hear from the OP more about his car - what’s been done to it (carb swaps are common), what’s the maintenance been like, etc, etc…

The Prince of Darkness strikes again! Will it ever stop?

Please come up with some more info.
Ignition system - points/condenser or electronic?, when was last service. Miles and months/years?
One or dual SU carbs (or other brand)?, heat shield - is that present between carb(s) and exhaust?.
Electric (which type) or mechanjcal fuel pump.
And this is just the beginning.
You cannot give too much info.

OP mentioned phase separation in the gas which leads me to think he is using gas with ethanol.

He said he’d check if there was separation. There are so many possibilities…