Triumph Repair: 1978 spitfire mk IV wont start, lrp petrol, spitfire mk

Question
I have a 1978 1500 spitfire that I bough recently. I was told by the garage where I bought it to use optimax/lrp petrol so I have. I was advised that I didn't need additive, I now know that to be wrong. It has ran fine the past 9 months but now it wont start.

I have added additives and petrol treatment.
I change the battery and when I cleaned the spark plugs it fires, it did start recently so I took it for a run (before I added the additives back into the petrol) I took it for a good long run, but alas it did not start and now just floods.

Could the change in battery or the lack of additives have caused this?

Any advice other would be immensely helpful.

Ben

Answer
ben I'm trying to get out of the answer business but i don't think the additives are needed. usually flooding ( gas pouring out from the carb throat ) is the needle and seat. the float goes up and pushes on it to shut off the gas. I've had trash get in between there and cause flooding. you might take the fuel bowl apart and look for dirt. sometimes just doing that will fix it. Dave