Does anybody know what the flow (cfm) is for the GM 416 (14014416) cylinder heads.  These heads came off of 305's.  I am looking at buying a set due to the small combustion chambers but wanted to know how they flowed.  Thanks  

I suppose these are going on a 350?

Back in the not so good ole SMOG days of the late 70's thru the 80s it was popular to put 305 heads on 350s to gain back compression without having to replace the pistons. But today there's so many better choices available this just isn't much done, especially when considering the cost of a decent rebuild against the cost of new heads, it becomes pretty hard to justify going this route.

For flow the 305 heads are marginal at best for a 350, they have 130-140 cc intake ports which at best will only flow about 150-160 cfm at .5 inch lift which limits RPMs to a bit over 5 grand before the engine falls on it's face. Porting is required but you've got to make the walls real thin where cracking becomes a serious problem for a street engine that has to go thru many heating and cooling cycles whiile maintaining reliability. The valves are small, and while 1.94 and 1.55 valves can be installed, it carves out the hardened seats pretty far and you can run into softer material which will lead to seat regression with unleaded fuels.

If you retain the factory pistons with their large circular dish and deep valve pockets, it still is a problem resisting detonation as this design just doesn't take advantage of the available quench area as effectivly as "D" dish or flat top pistons running under a 64 cc chamber.

I really can't recommend you go this way if this is what you're thinking, it's just too much expense for too little result. If you own or have access to the equipment to restore heads the answer for cost could be different, but otherwise if you do an honest cost estimate, you'll find the price of a reliably rebuilt set of 416s won't be far from a new set of SR Torquers for example.

Bogie  

Yes was looking at going on a 350.  Had a Local engine shop going out of business and they had several heads for sale, but I didnt know much about the 416 head.  Saw that it had small combustion chambers and it quickly appealed to me.  I was building up a 350 .060 over with 2 valve relief flat tops.  I already have several different heads that are "more desirable" but I wanted some flow data on the 416s.  Valve size is okay, but with the runners only flowing 160 cfm, it wont do what I need them to do.  Thanks.