A while back a person made this comment:
"We have built Pontiacs, Fords, Chevies, Olds, Buicks, Hondas, Mopars and others over the years. Most all have been on the dyno and the heads always on the flow bench. 14 degree valve angles have no bearing in this conversation and are meaningless. In fact, stock 14 degree Pontiac big block heads are TERRIBLE flowing heads and to claim that's something special makes their actual flow even more laughable. Even Stock Edelbrock heads are NOTHING to right home about. Almost any decent aftermarket 23 degree Chevy head is either going to equal a stock Pontiac head with the better CNC variations blowing away even the Edelbrock head, all 14 degrees of them. NOW, step up to a RR 23 or 21 degree or 13-18 degree Chevy small block head and your in a different ballpark compared to the typical Pontiac aftermarket head. Only the very best Pontiac big block aftermarket heads are going to be in the same range as what these upper level types of heads offer."
Now my question is which is it? In one sentence this person says 14 degree valve angles are meaningless and in another sentence s/he says step up to a 21 degree or 13-18 degree chevy small block head and you’re in a different ball park. Now I take different ball park to mean superior, untouchable, to create a gainful advantage.
Now we all know that the stock gen 1 sbchevy has a stock 23 degree valve stem angle but nearly all top dog aftermarket heads tilt the valve stems closer 10 and 4 degrees. For example Dart race series heads claim “Dart 15’, 16’ and 18’ aluminum small-block cylinder heads offer a dramatic performance improvement over conventional 23’ designs.” When moving up the ladder to a pro stock style Little Chief head (notice the Indian’ish name given to this head, kind of remind you of a brand P engine) the valve stems are further pushed to 11 degrees where they claim “The huge flow resulting from the 11 degree angle”. They say that if you want to build the “ultimate bad-nasty small block race motor, you want the Little Chief.” Does valve stem tip angles matter?
A flow test @28 of water showed that a sbchevy head casting # 462, 156cc, peaked at 218/142 cfm @ .600 lift, a 23 degree head. Going to a 13 degree valve stem angle TFS 200cc was able to squeeze out 265/211 cfm @ .600 lift. To keep it even, a WP Sportsman II 201cc, same valve size and port size flowed at 243/156 cfm @ .600 lift. That is a 22 cfm difference in intake flow comparing to approximately 45HP difference on a 8 cylinder engine.
Another flow test of mid to late 1970’s model Pontiac head 6X-8 with 153cc intake ports came in at 214/158 cfm @ .550 lift, 28 inches of water. A #16 head ported flows 250cfm @ .550 lift on the 160cc intake.
Before and after tests of Edelbrock 2.11/1.65 Pontiac heads flowed 290/208 cfm @.600 lift, 215cc and 299/217 cfm ported.
For comparison Edelbrock 2.02/1.60 Performer RPM sbchevy heads flowed 227/176 cfm @ .600 lift, 170cc and 248/192 cfm ported.
Now if remember, the above professional engine builder claims that “In fact, stock 14 degree Pontiac big block heads are TERRIBLE flowing heads and to claim that's something special makes their actual flow even more laughable. Even Stock Edelbrock heads are NOTHING to right home about. Almost any decent aftermarket 23 degree Chevy head is either going to equal a stock Pontiac head with the better CNC variations blowing away even the Edelbrock head, all 14 degrees of them”.
VICTOR 23° HIGH-PORT HEADS - APPROVED FOR NASCAR TOURING CLASSES
70cc combustion chambers #77559*
VICTOR 18° HEADS
52cc combustion chambers #77509*
65cc combustion chambers #77519*
VICTOR 18° HEADS - WITH SEATS .100" CLOSER TO DECK
65cc combustion chambers #77529*
65cc combustion chambers (no seats & guides) #77539*
VICTOR 15° HEADS
43cc combustion chambers (seats and guides not included) #77549*
PERFORMER RPM WITH ANGLED PLUGS
Chamber Size Intake Port Size Valve Sizes (in/ex) Bare (single) Complete (single)
70cc 170cc 2.02"/1.60" #60619* #60719*
64cc 170cc 2.02"/1.60" #60949* #60999*
PERFORMER RPM WITH STRAIGHT PLUGS
70cc 170cc 2.02"/1.60" #60639* #60739*
64cc 170cc 2.02"/1.60" #60889* #60899*
POLISHED PERFORMER RPM WITH ANGLED PLUGS
70cc 170cc 2.02"/1.60" N/A #607119*
POLISHED PERFORMER RPM WITH STRAIGHT PLUGS
70cc 170cc 2.02"/1.60" N/A #607319*
64cc 170cc 2.02"/1.60" N/A #608919*
.100 .600
#60719, #60739 73/61 140/108 200/144 238/163 244/175 244/183
PERFORMER RPM PONTIAC
Chamber Size Intake Port Size Valve Sizes (in/ex) Bare (single) Complete (single)
72cc 215cc 2.11"/1.66" #60589* #60599*
72cc (semi-machined) 215cc 2.11"/1.66"(B) #60509* N/A
.100 .600
#60599 71/69 143/120 208/151 253/173 272/191 286/199
By the way, a Edelbrock/Chapman 6104 head w/236cc intake will flow 314/250cfm @ 28”. These are 18 degree high dollar heads. What happens when we tilt these valves another 3 degrees with the Edelbrock 15 degree 283cc intake head? 363/254cfm @.600 lift.
I guess valve stem angle don’t matter?
This thread will only deal with Gen 1 Chevy small block 23 degree valve stem angle head vs. all other non 23 degree valve stem angle wedge/compound wedge Gen 1 Chevy small block head. This is going to be done to keep from stepping on other's toes or breaking someone's heart.
"We have built Pontiacs, Fords, Chevies, Olds, Buicks, Hondas, Mopars and others over the years. Most all have been on the dyno and the heads always on the flow bench. 14 degree valve angles have no bearing in this conversation and are meaningless. In fact, stock 14 degree Pontiac big block heads are TERRIBLE flowing heads and to claim that's something special makes their actual flow even more laughable. Even Stock Edelbrock heads are NOTHING to right home about. Almost any decent aftermarket 23 degree Chevy head is either going to equal a stock Pontiac head with the better CNC variations blowing away even the Edelbrock head, all 14 degrees of them. NOW, step up to a RR 23 or 21 degree or 13-18 degree Chevy small block head and your in a different ballpark compared to the typical Pontiac aftermarket head. Only the very best Pontiac big block aftermarket heads are going to be in the same range as what these upper level types of heads offer."
Now my question is which is it? In one sentence this person says 14 degree valve angles are meaningless and in another sentence s/he says step up to a 21 degree or 13-18 degree chevy small block head and you’re in a different ball park. Now I take different ball park to mean superior, untouchable, to create a gainful advantage.
Now we all know that the stock gen 1 sbchevy has a stock 23 degree valve stem angle but nearly all top dog aftermarket heads tilt the valve stems closer 10 and 4 degrees. For example Dart race series heads claim “Dart 15’, 16’ and 18’ aluminum small-block cylinder heads offer a dramatic performance improvement over conventional 23’ designs.” When moving up the ladder to a pro stock style Little Chief head (notice the Indian’ish name given to this head, kind of remind you of a brand P engine) the valve stems are further pushed to 11 degrees where they claim “The huge flow resulting from the 11 degree angle”. They say that if you want to build the “ultimate bad-nasty small block race motor, you want the Little Chief.” Does valve stem tip angles matter?
A flow test @28 of water showed that a sbchevy head casting # 462, 156cc, peaked at 218/142 cfm @ .600 lift, a 23 degree head. Going to a 13 degree valve stem angle TFS 200cc was able to squeeze out 265/211 cfm @ .600 lift. To keep it even, a WP Sportsman II 201cc, same valve size and port size flowed at 243/156 cfm @ .600 lift. That is a 22 cfm difference in intake flow comparing to approximately 45HP difference on a 8 cylinder engine.
Another flow test of mid to late 1970’s model Pontiac head 6X-8 with 153cc intake ports came in at 214/158 cfm @ .550 lift, 28 inches of water. A #16 head ported flows 250cfm @ .550 lift on the 160cc intake.
Before and after tests of Edelbrock 2.11/1.65 Pontiac heads flowed 290/208 cfm @.600 lift, 215cc and 299/217 cfm ported.
For comparison Edelbrock 2.02/1.60 Performer RPM sbchevy heads flowed 227/176 cfm @ .600 lift, 170cc and 248/192 cfm ported.
Now if remember, the above professional engine builder claims that “In fact, stock 14 degree Pontiac big block heads are TERRIBLE flowing heads and to claim that's something special makes their actual flow even more laughable. Even Stock Edelbrock heads are NOTHING to right home about. Almost any decent aftermarket 23 degree Chevy head is either going to equal a stock Pontiac head with the better CNC variations blowing away even the Edelbrock head, all 14 degrees of them”.
VICTOR 23° HIGH-PORT HEADS - APPROVED FOR NASCAR TOURING CLASSES
70cc combustion chambers #77559*
VICTOR 18° HEADS
52cc combustion chambers #77509*
65cc combustion chambers #77519*
VICTOR 18° HEADS - WITH SEATS .100" CLOSER TO DECK
65cc combustion chambers #77529*
65cc combustion chambers (no seats & guides) #77539*
VICTOR 15° HEADS
43cc combustion chambers (seats and guides not included) #77549*
PERFORMER RPM WITH ANGLED PLUGS
Chamber Size Intake Port Size Valve Sizes (in/ex) Bare (single) Complete (single)
70cc 170cc 2.02"/1.60" #60619* #60719*
64cc 170cc 2.02"/1.60" #60949* #60999*
PERFORMER RPM WITH STRAIGHT PLUGS
70cc 170cc 2.02"/1.60" #60639* #60739*
64cc 170cc 2.02"/1.60" #60889* #60899*
POLISHED PERFORMER RPM WITH ANGLED PLUGS
70cc 170cc 2.02"/1.60" N/A #607119*
POLISHED PERFORMER RPM WITH STRAIGHT PLUGS
70cc 170cc 2.02"/1.60" N/A #607319*
64cc 170cc 2.02"/1.60" N/A #608919*
.100 .600
#60719, #60739 73/61 140/108 200/144 238/163 244/175 244/183
PERFORMER RPM PONTIAC
Chamber Size Intake Port Size Valve Sizes (in/ex) Bare (single) Complete (single)
72cc 215cc 2.11"/1.66" #60589* #60599*
72cc (semi-machined) 215cc 2.11"/1.66"(B) #60509* N/A
.100 .600
#60599 71/69 143/120 208/151 253/173 272/191 286/199
By the way, a Edelbrock/Chapman 6104 head w/236cc intake will flow 314/250cfm @ 28”. These are 18 degree high dollar heads. What happens when we tilt these valves another 3 degrees with the Edelbrock 15 degree 283cc intake head? 363/254cfm @.600 lift.
I guess valve stem angle don’t matter?
This thread will only deal with Gen 1 Chevy small block 23 degree valve stem angle head vs. all other non 23 degree valve stem angle wedge/compound wedge Gen 1 Chevy small block head. This is going to be done to keep from stepping on other's toes or breaking someone's heart.