I'm going to be replacing my intake/exhaust manifold pretty

soon, so I should be eliminating most of the weird vacuum

leaks and such I've had.

After I do this I'm going to take the car to a buddy who has

a smog check station to try to check the mixture on the car

at various RPMs and under load. What sort of numbers should I

shoot for when setting the carbs? I've read that older cars

*need* to run richer than modern cars (hence you can't use a

generic O2 sensor), and I don't want to melt holes in my crazy

tractor's pistons...

thanks