ORIGINAL: Bipe Flyer
They all use special plugs, but the plugs are less expensive than an OS #8 and often last a year or more. I also have a TT .07, but it is heavier and not very powerful compared to the Norvels. I think that the Norvel .074 is one of the best sport engines of any size.
There is an option of using the Galbreath head with Nelson plugs on the .049 and .061 -- I'm not aware of a similar option with the .074. I also agree with Andrew's assessment of the .074 -- it s is a fine engine.
the "other" andrew