3406b low boost and fuel pressure issues

Usually that’s the govnor spring guide but it causes an idle down slow condition. You could have linkage/bushing issues though. I can’t remember if it’s been this way since you’ve had it or a new problem but if you bought it that way some Jack ### may have been in there muck in around and have it really messed up. Key on engine off tie throttle all way back. Pull the cover on front of fuel pump with 2 7/16 bolts. Has one identical to it on back side. Anyway you’ll see the rack when you pull cover. Take your finger and try to push it back some more. There is a plug right on top of it put your timing pin in there and it should lay right at the back of that groove you see in the rack. I’m terrible at explaining things but I can get a friend to get you some pics outta my service manual if you need them. Just might take some collaboration lol

 

I do not like below 650 or over 700. I have seen several arrangements that spec was 600. But I don’t like the sound that low it has almost a no oil sound usually

 

How hard is it to move? It should move by itself for the most part

 

Only ones I ever saw that sounded right running that slow were some 1800 rate 425 arrangements that were around in the ‘80’s.