ok doke . i have to very soon pull the intake and take a gander at the valves in the third cylinder on the passenger side of my flatty . i seem to have developed any number of possible things that basically has the valve , guide and all jumping up and down . she still runs fine , no miss or loss of power . it's the same cylinder that had the bent valve when i bought her . had to replace the guide and valve .well anyway as part and parcel of this whole lets take it aprt again ordeal , i am replacing the radiator , rebuilding the pumps , switching over to electronic ignition , electric fan to do away with the weird oe one , and a number of other things . well i am gonna run another leakdown / compression test as i seem to have a lil' extra pressure building up in the cooling system {and i got the feeling i'm gonna have to pull at least one of the heads anyway } . so i was wondering what would be the safest minimum to maximum amount i could mill off the heads to make sure they are straight , which we checked before and they were then . obviously i'll get the added benefit of a lil' more compression ratio . also and im assuming here , that i'm gonna have to put some sort of spacer / washer under the head bolts to keep them from bottoming out and damaging the block ??? am i correct ??

 

wow! getting serious on the flattie. what model flattie? i can't imagine that you will be cutting off any real meat on heads. especially if they were already straight. so, no, you shouldn't need spacers on bolts. almost sounds like guide seat was damaged with bent valve. how big a fan, cfm,s, are you using? thinking about doing this to my truck.

 

The tradeoff for a flathead with milling the head is that it reduces the transfer area between the valves and the cylinder. You really don't want to try to gain compression by milling; it's a futile exercise. The only practical way to inccrease compression is to stroke the crank, that's why Merc cranks are so valued.

So anyway, if they need the milling to make them flat, don't go any more than needed. If you have to go more than .020", you'll want to check to see what the valve-to-head clearance is afterwards, using a used head gasket and with clay on top of the valves.

As far as the valve jumping up and down; is the clip still there? I don't see what else could allow the guide to move except a missing clip.

 

ross milling the heads is only if they need it . yep im thinking a clip exited stage left , but although she's sitting right now , i still haven't had the opportunity to get her apart yet . the head gaskets are leaking too , so the whole top end is gonna come off . four cylinders ; 1,5,7,8, are carrying almost 120 lbs. the other four are at 90-95 , so im gonna assume head gaskets are going away . petey it's the ol' 8ba thats been in it for many moons and im gonna assume since new . the fan issue , well i haven't had a chance to fully investigate and ask what i need of the many manufacturers out there as i am literally at work all the time as of late , and when not looking for parts for the various wild hair up my a-- ideas . still gotta go part the 61 one ton for it's gauges and switches , and get over and drag that pos 55 home to part as well as all the dain work on the 53 that has to be done ... anyone know how to clone ???????????????