geckonz08

I have heard and read about how some olds heads flow better than others ; that the c heads in BBO are regarded as the best but A to F vary from C by approx. 10% or so.; and that Olds heads generally are not the best flowing heads.
Fair enough .
But what are we comparing them too ?? BBO to BBC to BBF ?? edelbrock? other? and if so, by what %^ are we missing out ??
Anyone assist with some knowledge or figures pls ???
mike

J-(Chicago)

Stock Oldsmobile Edelbrocks according to MJproformance.com with a single back cut on the valves.
Lift Intake Exhaust E/I ratio
.100 80 63 79
.200 148 105 71
.300 203 138 68
.400 237 166 70
.500 251 175 70
.600 257 180 70
.700 257 183 71


Stock flow numbers according to midamericaperformance:
BIG BLOCK INTAKE PORTS (STOCK)


Valve Lift
A B C D E F G&Ga H J Ka

.100 84 85 85 92 89 92 91 87 81 85
.200 159 159 162 164 156 165 158 159 144 157
.300 208 209 211 207 215 210 205 209 206 209
.400 233 232 233 228 243 227 225 232 223 224
.450 243 244 244 233 246 234 231 239 225 231
.500 250 250 250 239 250 240 236 243 227 236
.550 254 253 253 243 252 242 237 245 227 237
.600 259 258 259 245 253 244 239 248 227 239


BIG BLOCK EXHAUST PORTS (STOCK)


Valve Lift A B C D E F G&Ga H J Ka

.100 54 50 49 50 48 49 47 50 49 47
.200 101 99 99 98 92 99 96 98 89 94
.300 135 133 133 133 127 129 129 131 121 126
.400 151 146 145 147 147 144 145 147 125 144
.450 154 152 151 153 153 148 151 153 126 149
.500 160 158 158 157 158 154 156 158 126 156
.550 163 161 160 162 162 158 158 162 127 150
.600 169 163 162 166 166 162 161 165 127 161



Looks like they all suck equally to me.
You could google stock Chevy and Ford numbers and compare if you like. Olds heads all need some help in the bowl area to start flowing decent.

geckonz08

Tx for those J -chic.Have been googling flat out --They (chev n ford ) must be hiding the figures .All too happy to show their modern, flash ,cnc jobs --will keep searching.

Your figures above seem to say that the A B C D E F HEADS are all within a WHISKER flow -wise --seems as though porting , milling and valve size will make the only real difference

Smitty275

Correct. Porting is what makes the big difference. In the hands of a good porter any of the factory iron BBO heads can be made to perform exceptionally well with intake numbers of 300+cfm and exhaust numbers of 200+cfm. The J heads intake runner cannot be taken quite as far as the others but it is still a very good head to work with especially for street and mild strip application. Plus people will usually give you their worn out J heads for free.

geckonz08

Tx Smitty. So, it seems that the c heads being the real good uns is possibly correct but they ain`t that much better .As one chap ( whom I haven`t seen here for a while )used to quote regularly " urban myth "