Reply to "Edelbrock 351C Head Flow Numbers"

Not sure if the forum software will preserve my formatting but here's some additional head flow data on the Ford high port head family:

Valve C302 C302 C302B C302B C302B A3 A3
Lift Intake Exhaust Intake Exhaust Exhaust Intake Exhaust
(inch) 2.15" 1.65" 2.19" 1.65" 1.65" 2.19" 1.71"
Tulip Std (from
C302)
0.025 --- --- --- --- --- 33 33
0.050 063 047 051 --- 047 48 45
0.100 096 073 081 --- 073 84 67
0.150 125 102 120 --- 111 119 86
0.200 160 123 157 131 124 154 108
0.250 --- --- --- --- --- 187 128
0.300 218 155 223 180 156 211 142
0.400 274 191 266 210 188 257 169
0.500 313 220 306 223 206 299 191
0.600 318 234 331 228 215 327 214
0.650 --- 241 --- 230 220 --- ---
0.700 --- 242 --- --- 222 309 226
0.800 --- --- --- --- --- --- 234

The flow is in CFM and was tested at 28" pressure drop on a SuperFlow 600
flow bench at Stiegemeyer Racing Heads in St. Charles, Missouri. A 4.155"
diameter tube was used to simulate the bore and the intake was flowed without
a manifold, using a piece of clay around the intake port. No pipe was used
on the exhaust. When Dave Williams had a pair of iron 4V Cleveland heads
tested on Jim Kuntz's bench, the operator mentioned that naked intake ports
usually flow 20-30 CFM less than a port with manifold. I'm also told an
exhaust port with pipe picks up a similar amount.

Both sets of cylinder C302 heads have had some work done to them. The bowls
were blended and the ports smoothed but the ports were not hogged out and
remain fairly small. The C302B's have intake port volumes of 217 cc's and
exhaust port volumes of 112 cc's, roughly similar to the CHI 3V heads. The
C302B's were also fitted with titanium tulip exhaust valves. We swapped a
standard exhaust valve from the C302 head to see how it compared to the tulip
valve in the C302B. Note that the valve was simply dropped in the port and
flowed, no valve job was done. Stiegemeyer says the tulip shape works even
better on heads with large seat areas but makes the valve heavier. That's
not a problem with titanium but I plan on swapping to stainless steel instead
since my engine is a street stroker and won't be turning extreme RPM.
The A3 heads were not ported but were given a quick clean up with a sanding
roll.

Stiegemeyer likes high flowing, moderate cross-sectional area, cylinder
heads mated to high flowing single plane race intake manifolds (Roush/Ford
Motorsport, Edelbrock Victor and the like). More than just the raw CFM of
the heads, he was quite impressed with the velocity of the C302 and C302B
heads and thought either pair would make for a killer street engine.
Actually, the heads flowed a bit better than the numbers suggest as the
lifts were actually lower than the reading due to the angle required by
the test fixture (the lift gauge was at an angle to the valve). Stiegemeyer
has since ported a friend's set of C302 heads which flowed over 350 CFM on
the intake side.

Dan Jones