What fuel do you use? Any additives required?

for your 1974 mgb, you can use 87 octane, however you will need to add lead additives. if not you could damage your valves. if you have any other questions, about that particular car feel free to ask me. there was a time in the early eighties when I had 4 mgb gt. and one mgb.

Depends on your cylinder head, if it's been converted to unleaded (i.e. hardened valve seat inserts) there's no problem with running 95 RON (85 MON), you only need lead additive for an unconverted head. Also be wary of running alcohol rich fuels like E85 if you have viton tipped float needles, the alcohol tends to greatly reduce their lifespan.

Read the fuel additive label!

Thanks for the info so far. I have a 1977 MGB and I do not know if hardened valve seat inserts have been installed. Is it OK to add lead additive to the gas whether the valve seat inserts have or not have been installed? In other words, If valve seat inserts had been installed years ago before I bought it, Will adding a lead additive to the gas be a bad thing to do? Minnesota Guy