I have McCoy Testers O&R and K&B and they all still run, remember the old fuels that you could not get to burn and buying Caster at the drug store and mixing your own with a little either blowed the head clean off a 35 . I payed $4.95 for 29's ND $5.95 FOR 35'S in late 40's The speed engines sold for about $10.95 with the rear intake those were the days.