Valve C302 C302 C302B C302B C302B
Lift Intake Exhaust Intake Exhaust Exhaust
(inch) 2.15" 1.65" 2.19" 1.65" 1.65"
Tulip Std (from C302)
0.050 063 047 051 --- 047
0.100 096 073 081 --- 073
0.150 125 102 120 --- 111
0.200 160 123 157 131 124
0.300 218 155 223 180 156
0.400 274 191 266 210 188
0.500 313 220 306 223 206
0.600 318 234 331 228 215
0.650 --- 241 --- 230 220
0.700 --- 242 --- --- 222
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 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. I will measure the port cross-sectional areas this weekend but I still need to order a set of snap gauges to check the minumum areas. The C302B's, in particular, have a fairly small minimum throat area. My guess is they were originally set up for a restrictor plate engine. 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 was planning on swapping to stainless steel instead. An intake valve in one of the heads was given a quick back-cut as he didn't like the shape. I forgot to note which set it was from so I'll need to disassemble them to know for sure. Stiegemeyer says he has had a problem with Del West titanium valves pulling the heads off the stems (monster spring pressure) but hasn't had any trouble with other brands. He did not like the teflon valve seals that were on the heads as they do not allow enough oil through for lubrication and pulled out another seal type that he uses now.
By way of comparison, I have some flow data on some old NASCAR racing
heads that went through a shop that Chip Barret-Smith worked at. He
said the bench they use posts numbers that are a lttle more conservative
than what a Superflow reads.
Intake Flow
Bud Moore Wood Bros Davis Racing Stock
Lift C302 canted Yates head Yates head C302
-----
0.050 33.10 30.10 29.3 30.4
0.100 69.10 66.10 63.6 66.2
0.150 115.4 104.6 102.1 97.4
0.200 152.2 144.7 138.9 129
0.300 217.5 220.8 214.1 189
0.400 267.7 277.7 277.7 229
0.500 306.2 314.5 324.6 246
0.600 332.9 311.2 326.2 251
0.700 ----- ----- ----- ---
0.800 ----- ----- ----- ---
Exhaust Flow
Bud Moore Wood Bros Davis Racing Stock
Lift C302 canted Yates head Yates head C302
-----
0.050 21.40 21.40 23.90 28.3
0.100 50.20 46.00 51.00 57.7
0.150 78.60 72.80 77.80 76.8
0.200 108.7 95.40 100.4 93.9
0.300 142.2 138.9 135.5 108.0
0.400 202.4 179.0 187.4 116.6
0.500 219.2 214.1 212.5 119.4
0.600 224.2 237.6 227.5 ----
0.700 234.2 249.3 230.9 ----
0.800 235.9 254.3 ----- ----
Note: The Yates heads have 2.1" intakes and 1.6" exhausts.
The canted valve heads had 2.15" intakes and 1.65" exhausts.
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). It might be worthwhile to pour some rubber molds of the ports and make a set of templates.
Stiegemeyer usually starts flowing heads at 0.200" lift but Vizard's instructions for the cam selection software require low lift numbers, so I had him add a few low lift points. Stiegemeyer asked a few questions about the Pantera and wrote down some cam specs he thought would work well for what I wanted to do. The numbers were close to what I was expecting: single pattern, 260 degress @ 0.050" on a 108 LSA, installed at 105 degrees with 0.645" lift if solid roller, or 0.600" lift if hydraulic roller. That was assuming the independent runner EFI intake. He would drop the duration by 10 degrees if a single four barrel. He said the 4" stroke crank would cause it to peak at around 6000 RPM and thought I could make better power with a 3.75" stroke crank shifting at 6800 RPM. He said I'd give up some torque but wouldn't miss it on street tires. He also thought I should go no larger than a 1 7/8" header. After seeing the flow velocity of the heads on the bench, he thought the lobe separation could be widened slightly to 109 degrees.
I took along a stock rebuilt 1964 Buick 300 aluminum cylinder head to put on the flow bench. I wasn't expecting them to flow very well but wanted to get a baseline to compare a ported set against. They actually flowed better than expected:
Valve 1964 Buick 300 Ford 5.0L
Lift aluminum heads cast iron
(inch) Intake Exhaust Intake Exhaust
1.625" 1.312" 1.78" 1.45"
0.200 105 096 092 078
0.300 135 108 130 095
0.400 142 115 141 102
0.500 149 115 155 106
0.600 154 116 158 105
Same flow bench conditions as the C302's. Stock heads with stock valves
(standard valve job, no port work). The Buick 300 heads are an upgrade to
the Rover and Buick 215 aluminum V8 engines but still have small ports and
valves. For comparison, I've included flow numbers from a 5.0L Ford head
from Fordmuscle.com. I had seen flow numbers that suggested the Buick 300
heads flowed as well as Ford 5.0L heads but given the smaller ports and
valves, I really didn't believe them. I still plan to port the Buick 300
heads but was pleasantly surprised with the baseline numbers. It was funny
but I think Stiegemeyer got a bigger kick out of the little Buick heads than
he did the much higher flowing high port Motorsport heads. We discussed that
engine project briefly and he offered to weld up the combustion chambers and
rough them in for $250. I might just take him up on that. After reviewing
the flow chart for the Buick head, he warned you against over-scavenging the
exhaust side. I may head back with my home-ported Buick 215 heads to see how
they do. I increased both the intake and exhaust valve sizes but went
relatively larger on the exhaust and that was probably a mistake. I knew
better but the valves were on hand so I went with them. I'd also like to get
my A3's on the bench to see how they do.
Stiegemeyer's shop had a wide range of cylinder heads waiting to be worked on, including the usual small and big block Chevy and Ford, 392 Chrysler hemi, Ford 3.8L V6 (max effort pieces supplied to a Ford V6 specialist), Fiero four cylinder (tiny ports) and even a set of A3 high ports (for a sprint car). While we were talking, Stiegemeyer pulled out the flow sheets on some iron 4V's that he did as a "budget deal". No port work was done but different valve margins were tested, along with the Roush-type port stuffers. I didn't get a copy of the sheets but they showed a stock iron 4V head pulling 294 CFM (which just happens to be the same number that Dave Williams got on a set of stock 4V Clevelands). With no porting but with a fancy valve job and the port stuffers, he made 331 CFM with higher velocity. For so little effort, he was pleased with the results and said the engine made very good power.
In addition to the cylinder heads, there was lots of neat stuff around the shop including an old Mercury Comet rolling chassis (straight axle front, tubbed rear) set-up with a Donovan aluminum SBC, a 392 hemi with mechanical injection (along with a plastic mock-up). Stiegemeyer makes the nicest and strongest valve spring compressor I've ever seen but at $850 I won't be picking one up any time soon. While I was there, a guy rode up on a 3-seat SBC V8 powered trike that looked like it time-warped out of the 1970's and just before I left I got to help push a Chevelle up on a trailer after it twisted its driveshaft in two on the Dynojet.
Dan Jones