'1967 Holiday Race' ~ Plymouth GTX 440 vs. Pontiac GTO 400 'Ram Air'

TheseQUOTE=fratzog lover;1971068712]Wallace racing (Pontiac) cylinder head test. Conclusions:

I have no doubt that these figures are going to cause some conster*nation among a number of HPP's readers. The "I told you my head is better than yours" contingent should have a field day.
Before readers jump to conclu*sions based on airflow numbers alone, however, they must take into account all the other factors that compose a total engine combination. A well-set-up 400-cid engine with big-valve No.16 or No.48 D-port heads is going to run just as well as another engine with Ram Air IV heads, if the tuner doesn't have enough cam and gearing to utilize the higher-lift airflow
I'm sure our readers are quite capable of drawing their own con*clusions with respect to some of these heads. I cannot resist the temptation, however, to list a few of my own opinions (see “Pete's Picks"). Whether you agree with these assess*ments or not, I would imagine that most Pontiac die-hards will find the numbers researched to be of great interest.
We'll get into the complexities and complications of porting various Pontiac heads in the near future. I promise you that the surprises will be many.
Interesting on the

Best performance head 1970 Ram Air IV
Best intake port 1969-70 Ram Air V
Best exhaust port 1 968 1/2 Ram Air II
Best D-port head No.16, No.48, No.12 (tie)
Best low-compression D-port head No.96(1971)
Best low-compression post-1972 head No. 6X
Best balanced head (exhaust to intake) 1963 421 SD
Best low-lift (under .400) head 1967 No.670
Worst exhaust-to-intake port ratio 1969-70 Ram Air V
Worst intake-to exhaust ratio 1968 1/2 Ram Air II
Biggest surprise Intake port, No.17 350 head
Biggest disappointment 1969-70 RA V, 1973-74 455 SD (tie)
Biggest "sleeper" 1975 No. 5C
Most undercammed 1963 SD, 1971 455 HO, 1973-74 455 SD (tie)
Most underexhausted 1964 GTO (No.9770716)
Most potential for porting 1973-74 455 SD, 1968 1/2 RA II (tie)


A good low lift head.[/QUOTE]

Interesting ,on the 16 castings..I new they were good,not that good.. ( traded a set of 7K3 ported castings,for 16 castings. They lapped fair, loose guides...) The compression went 2 + points up, you already know what happens here...That 17 casting,is interesting.. Picked up a set for free, seemed to have a different intake port...