Normal valve sizes are 1.875" intake & 1.500" exhaust from '57-'66 364/401/425. The lower performance 364/2bbl. low compression engines from '57-'59 "sometimes" have smaller intake & exhaust valves, although they can accommodate the larger valves. These 2bbl. heads are supposed to have smaller combustion chambers cc's also. As far as I know the ports sizes are the same. The ONLY real differences I know about are the seals added to the intakes on the '66 heads. Also, don't forget the stock tulip intake valve have a 3.7-4.0 cc capacity. So to increase or play around with compression ratio in each separate combustion chamber to equalize cc's all one has to do is to use a "flat" faced valves. On engines that have tuliped exhaust valves even more compression can be realized with flat faced valves.
I wont get to play with the car until the weekend, so if I can get a set of valves out then, I will measure them, not so sure on cc,ing the heads though as I dont really know how (I assume you would fill the chamber with clay and then see how much water it displaces?), but I dont have the clay (I do have water though ) Mick
Good information. I would really like to know if there were in fact 364 heads with less CC's. Any machine shop should be able to CC your heads, however this is how it is done: https://youtu.be/V7V40ZWNgCo
Ok, I got 129ml, so thats 12.9cc I think? So thats on a 1958 364 40 series head I havnt pulled the valves yet, but I think there are 2 valve sizes, but I thought it was valve stem length that was different? Mick
Pulled 1 set of valves and got Intake are 1.875", but the exhaust are smaller at 1.427, valve length is 4.787" Mick
Sounds like the taller pistons will be just fine then since the combustion chamber seems to be the same. The later heads have larger exhaust valves (1.50")
Cheers Mike Might do some more measuring once I get everything clean Surely 1/16" wont make any problems going by where the ridge from the top ring is, but far better to be safe than sorry Mick
