46 casting head, what valve length??
 

I have a set of 46 heads. What should the valve length be?? I have a set that are 5.08, and a set that are 4.99. I am not sure what I should be using!! Thanks. Aaron.

It might make a difference to know if they are 1969 or 1973-74 style.
And if they have screw-in studs.
Just to be sure

Sorry. They are 1973 casting, and have press in studs.

Valve length really depends on what you have in mind for the heads. If you are doing a stock rebuild, then stock or near stock springs will be used. There is .090" difference between those two valves - or a nice .060" locator under the valve and a .030" shim for the taller valve to have the same installed height as the shorter valve. So either would work. Another consideration is whether the valves are recessed into their seats, because that might require the addition of thicker shims to maintain the correct installed height for the springs. After the valve job is complete, test fit the valves and see which one is closest to the correct installed height required for the springs used. What worked best when the head was new, might not be the best choice today.

The shorter 4.98" is the factory length for 1973 #46 heads.

If the heads will get a valve job done before use and your cam choise will not extend past .500" lift, then stay with 4.98" valves but be sure to have the guide tops cut for positive type PC seals if your valve lift will go over .480"
A nice change while having a valve job done and to add more power is to step up to the larger 2.11" and 1.77" valve sizes.

If the #46´s are staying on the 350 i would keep the 1.96"-1.66" valves.
On a 400 or larger engine the larger valves may be beneficial.

Thanks for the help. It doesn't much matter anymore, as I was porting them today, and hit the water port. Bummer. Aaron.

The 46´s should be plentiful at your side of the ocean, just get another pair and get on with it! Look for the threaded studs though.

I scrapped several sets of those, still have one set with screw in studs in the shop I think, you should be able to find them close

Into water jacket or the pushrod bulge? Figured I'd just double check.

Into the water jacket, right next to the guide, in an exhaust port.

Too bad, that hurt`s, plus flat top boss section is one of the least productive parts of the port to spend time and effort on .