So in other words the typical 240-250cc aluminum head/9.5:1 compression/shorty header/2.5" exhaust 302 is not the best home for a B303.
A 240-250cc head on a 302 is hardly typical, did you mean 240-250cfm?
I reverse engineered the FMS cams a long time back.
The B303 fits over a range of combinations with inlet flow in the mid 200's (*at 28"). assume low to mid exh/int 75%
With total inlet flow in the 220-230 range, the motor will require 1 3/4 headers and 3" exhaust, and a minimum of 10.75:1
With total inlet flow in the 240-260 range, the motor will require 1 7/8 headers and 3" exhaust, and a minimum of 10.75:1
In a 300cid motor, max rpm will be in the 6400-6800 range. In a 350 cid motor, max rpm will be in the 6000-6500 range
Cylinder pressure is critical. the ramps are a little lazy, therefore for the seat timing, the actual lift area is low. This will require additional static compression (as evident in the 10.75). Outside of these paramaters, the cam is far less than optimum. many will say their car flies, but with these relationships it will really fly. The inlet and outlet relationship and static compression are the key.
These set-ups allow the engine flow parameters to match the valve events as good as possible. In these cases, is the FMS cam the best cam? no. But if you want the FMS cam to do its best, this is what it will want.
Kind of funny this comes up. From what I can find the B cam is a crane flat tappet profile for a big block chevy. They list the specs on their lobe catalog, as are most of the other FMS cams
I'm in the process of building a cheap engine using a 1986 flat top shortblock, ported GT40 heads, a B cam, of course, 1.7s, beehive springs, and the headers and exhaust I've got on my 90LX which are the 1 3/4 accufabs, 3" exhaust. Compression should be 10.4, not going to spend money to deck the block, although that would help aid compression I'm sure. Because I'm using a Vic Jr with a 4 hole throttle body I'm thinking I'll advance the cam a couple degrees. Seems to me an engine with a short runner, small plenum intake would need the earlier intake valve opening, whereas a longer runner, larger plenum intake would benefit from the later opening, so this cam would be best installed up to 4 degrees retarded. Is that not adviseable?