Smoky petrol on starting

Got a petrol 90, so posted here as it is n/a. it runs well and starts well from cold but when it's hot it is a bit reluctant to start sometimes (not always).

When it is reluctant it will then start with a big cloud of grey/blue smoke (no smoke at any other time). It's 2.5L with the twin choke weber. Do you think this is a carb issue or is it oil via the valve guides (although as I say it doesn't always do it). If it's the carb, any thoughts on how to fix please?

Thanks

would say its valve guides as the smoke is from oil, when its warm the oil is thinner and seeps into the piston chamber. You try to crank it over and immediatley oil up your plugs causing a poor spark, hence no firing....

Thanks - That's kinda what i thought but my hope was it only does it occasionally so it might be carb related. Head-off job then this autumn.

just a forethought, I did work experience in Appleyards (was a rover dealer) and when we did the valve guides on some engines, sometimes we didnt take the head off. Just adapated a compressed air line into a spark plug size adapter to fire compressed air into the barrell so the valves didnt drop... saved removing the head..

Although, if you take the head off at least you can see if everything else is ok, maybe be worth checking your valve seats as well, jsut to make sure they're not losing compression. Easiest way is to turn the head upside down and poor petrol into each cylinder port onthe head. As long as no petrol "leaks" away faster than the others then all should be ok