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head flow comparo - maybe of interest

June 11 2012 at 6:33 PM

James K  (Login 351CRanger)
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Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?

A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.

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