Vacuum advance flame trap - is it necessary?

[GavinL]

The vacuum advance pipe on my '68 saloon has a number of dodgy extra joints where the copper pipe has previously broken, so needs replacing. My question is can I replace it with plastic pipework with no flame trap, like that fitted to A series Midgets? If it's not required on Midgets why does the Moggy need a flame trap?

[Rasputin]

I have had the plastic pipe on my pick up for eighteen years with no problems.

[RobThomas]

I'd assume that the plastic pipe, being a slip-on type, can be popped off by high pressure if there was any sudden backfire in the carb, thus saving the diaphragm. The early pipes were held on with solid fixings so maybe they needed the flame trap more? Not sure, so just a guess.

[Monty-4]

The plastic pipes seem to be fine although I do worry (with no evidence) that they could shorten the life of the advance diaphragm. The modern rubber ends seem to degrade at an alarming rate too.

The metal one is far prettier!