Can somebody tell me about 351C heads? Like the differences between 2V and 4V , the different valve sizes used and the chamber sizes . Also is there any benifit to using 2V open chamber heads with flat pistons and 2.18 intakes over 4V or closed chamber heads. This is on a 351C with a 396 stroker kit. I want to use this in my 94 F150.

 

There's 3 basic groups: (1) 2V-Used 2.04/1.66 valves with flat tops for a 9.5:1 comp ratio. They had 76.2cc comb chambers. (2) The next is 4V/CJ-They used the same valves (2.19/1.71) but the 4V used smaller comb chambers (62.8) to make 11.0:1 comp ratio. The CJ used the 2V comb chamber essentially (75.4cc). And (3) the Boss/HO-They also used the 2.19/1.71 valves, however the Boss used 66.1cc heads with pop up pistons to make 11.7:1 comp ratio. The HO utilized 75.4cc heads with flat top 9.2:1 comp ratio. These two were both adjustable also.
I am thinking that the last 4V may of had 2V valves with slightly larger comb chambers but this was like the last year of production (1974?). The comp ratio was down to like 8.7:1.
From my experience (that being drag racing a '72 Mach about 15 years ago with several Clevelands) I would use the 2V/open chamber heads unless I was building something for the track only (meaning high rpm launches). The 2V flow so well that with a valve job and some decent valves the heads will never hold you back. I would probably raise the comp ratio up a little to the low/mid tens though. On the other hand the other heads (meaning non 2V) flow soooo much that at lower rpm's they are a dog. I was getting my but kicked on the street with CJ heads and ended changing to 2V with '79 351M valves (longer stems/same size). Unless I could do a big burn out to heat the slicks so I could launch at 4500 rpm, which is hard on the street. You can have the pedestals machined off the non adjustable heads, install studs and you have a adjustable valve train. Crane and Comp used to carry the stuff.