The tech website says that all plugs on tecumsah engines is .030
I have used a Champion RJ19LM or J19LM, both work fine.
No way of knowing without much more info.
Get the model # and click the link I will post.
Put lots of oil in the cylinder through the spark plug hole, and let it sit overnight.
10HP to 20HP according to engine displacement and condition.
Check wires for insulation cracks. Buy an electronic (solid state) ignition conversion from Stens for $10 and install (instructions come w/kit). This will bypass old and unreliable condensor and point ignition system.
Should be 36 ounces + 4 more ounces if it has an oil filter. Just do not overfill it.
http://www4.briggsandstratton.com/miscpdfs/RNT/Engine%20Specifications%20Chart_ms3992.pdf
Because a 5hp motor does not have enough power to turn a 10hp load.
10HP Subaru gas enginereferenced: http://www.acehardwaresuperstore.com/coleman-powermate-5000-generator-p-88980.html?ref=42
Horse power calculations consider several variables, but for rotational engines, the formula is (torque x speed)/5252; Where torque is in lbft and speed is rpm. For the 242 series engine with an estimated 8.5 compression ratio, the engine is 10HP.
It depends on how you tune it. They can be about 10HP from the factory as is, but after tuning and/or using good gas, you can get about 17 HP max. I am 14, so this may not be the "best" answer, but I do know how much the engine should produce.