16HP Vanguard Engine Over Revving Question
 

I have a 1995 Cub Cadet 1641 (B&S Vanguard twin horizontal) that threw a rod and I’ve installed new rods, pistons & push rods. I followed the service manual instructions to set the governor. The problem I’m having is it wants to over rev. It starts fine, moving the throttle lever to ½ it revs up - throttling back down it goes to idle. Same when I cycle to ¾ throttle, no problems. When going to full throttle it wants to over rev, pushing the throttle down has no effect I have to turn the key off. Engine off the governor arm it moves freely and the governor shaft turns like normal. The really confusing thing when restarted it immediately over revs. I can move the carb butterfly lever to slow the engine down, but if I let go it goes back to over revving. I’ve pulled the crankcase cover twice and checked the governor weights and spool and they’re in the correct place and move freely. Put it back together and for whatever reason it run fine until full throttle. I thought about an air leak but think shutting the engine off would reset it. Would appreciate any advice.

Isn't the vanguard 16 a v engine?

Either way, that's odd, but it must be something in the throttle control.