Misfire

[Mileso]

Hi, My S4 on SU's misfires when pushed hard after a good warm up, also after over run into/out of roundabouts (do all Elans pop and bang on over-run!). Not consistantly though. To save chasing my tail I am guessing the right thing is to just taking to a rolling road tuner?

[BrianA]

I'd be looking for an air leak on the inlet manifold from your description.

A worn spindle in the carb could also let in air on the overrun causing popping and banging - had this with a pair of SUs on an XK120.

Certainly worth a look

[USA64]

It should have Stromberg not SU carburetors. Have you topped them up? The Srombergs have replaceable spindle seals.

[Mileso]

Apologies, yes its strombergs.