Ok I have a mildly built 340 4 speed when in nuetral and I rev it up I get a sqealing sound and when I wind it out alittle at a higher rpm I get the sound in all gears and I am not close to redlining it driving normal there is no sqeal and runs great so what could this be

 

This might be the obvious but it could be as simple as just a belt squeal, it is common to only show up under load or when the motor is revving quickly as that is when the most stress is put on it, I would swap on a new belt(or both) before going any further-if that doesnt fix it try to get a video of the noise or give more info-good luck!

 

Turn headlights and fan motor on to see if a load on the altenator changes the noise.

 

Sorry forgot to say in first post already changed belt that was my first idea. No change with lights on fan on high plus added radio on still squeals. Thanx to both of you for your ideas anymore ideas would be great!

 

Next thing to try is without the belt for a short time to eliminate alt and water pump bearings as the source.

 

Throwout bearing?

 

i had a similar issue
it turned out to be the carb gasket the bolts wer tight but the gasket wasn't sealing the carb and the air being drawn through was making a horrible squeal just as yours symptoms if the gasket is old maybe replace it might be your issue hope this info isn't to old to help

 

THAT was my first thought after i read the first post. Does it quit when you push in the clutch or change pitch? May not have enough 'free play' in the adjustments.

 

pilot bearing perhaps along with throwout bearing

 

Make sure ALL your pulleys LINE UP. I had the same problem, my alternator pulley was off a little bit (behind the crank pulley). Fixed it with a couple of washers, (3/32).

 

any luck yet