Reverb

How much movement should there be in a 4V 351C valve - I mean lateral not up and down. Mine, with no spring or seal, move a small amount.

67mustang302

With the head off, and holding the head of the valve with it slightly open, there should only be enough movement to feel, but not really see. Guide clearance is one of those things in an engine where you don't measure it, you feel it. Technically it's prolly only like .0015" intake and maybe .002-.0025" exhaust. It ain't much, but just enough to feel. If it feels sloppy, then it is.

my77stang

nah you should be able to see the movement, but it shouldnt be "sloppy". check your exhausts, they are usually looser and its usually the ones towards the center of the head.

if i had to give a number i'd say 1/16 of an inch movement up and down with the valve open to the point where the tip of the valve is flush with the top of the guide is ok, but 1/8" would be sloppy.

dgulian

You should not feel any movement and remove the valve seals first. .001 to .0015 max. Check the valve on the stem area that is moving in the guide. I check mine with a dial indicator on the valve head and with it held open about 1/4 inch. move the stem on the spring side in line with the indicator. Once they get enough wear to feel the seat will be beat to death. I have found most of the wear in the guide from side to side due to the rocker movement. Ant thing over.0015 on the exhaust could cause a hot valve head. the heat will not transfer well. I have seen detonation problems from this after a couple of hard runs.

67mustang302

There should be a little movement when cold. Once it heats up and expands, the movement is gone. Whether you feel it or not is going to depend on how far the valve is open when you check, the farther you pull it open, the more you'll feel it. Depends on the valves too, the newer sodium filled valves that are on GM's LS7 will have a much tighter cold clearance, since they cool better and don't expand as much.

my77stang

also a smaller stem feels looser. some of the newer DOCH stuff with the smalllllll stems feel SO sloppy, but they arent.

im a firm believer that when it comes to a motor a little loose is better than a little tight. i go by feel since i did heads ALL day long at work, but with something hipo im happier with .0015 and .0025 than .001 and .002

Reverb

There really isn't alot of movement there. I bought the heads used, but they look like they've had new seats. It's not going to be running until the car is ready so everything is still in boxes. It's got milodon valves. I wasn't too worried about it as I figured the springs and valve stem seals will keep it in place. Rocker rollers won't be putting too much side force on it anyway so should be fine.

dgulian

The springs and seals will not keep the valves in place. Don't short cut the engine. Have you rebuilt an engine crank up?

Reverb

I've rebuilt many engines crank up. This is the first one I've dealt with that has so many aftermarket parts available. I'm from the UK and we don't have the luxury there unless you go german or japanese. I'm going to get a dial gauge and check movement, but from what I've read above the movement I have is normal.

67mustang302

+10 billion on a little loose > a little tight.

Too loose will live, too tight won't. A little extra bearing clearance, a little extra piston clearance, a little extra ring end gap.....I sleep better at night that way. Besides, I'd rather take up the extra .001 clearance with a HV oil pump or heavier oil, than burn my engine up. Granted, you don't want it too large either.

And yeah, the springs/seals etc are NOT going to hold tht valve in place, that's what the guide is for. Take it to a shop and have them check it out, they should be able to tell you if it's good or not if you're really not sure.