[rotdog]

Trying to figure out what the diffrence is other than year. Any info would be apreciated.

[Tom Vaught]

The valve size is identical. The spring height will be identical. The springs will be identical as will the other valvetrain parts.

The 64 head # 716 naturally is the last year of the early head Intake bolt pattern.

The 65 head # 92 naturally is the first year of the late head Intake bolt pattern.

All of the cast iron heads, EXCEPT for the 421 SD, RA-IV, and 455 HO/SD will flow about the same. RA-III and "Tri-Power heads" are same as stock as far as real flow goes.
A 421 SD, RA-IV, and 455 HO/SD will flow about 220-230 cfm out of the box compared to <200 cfm factory (normal Pontiac) head.

If you are restoring a car, still lots of these heads (716 - 092/093) out there cheap.

Tom Vaught

[John V.]

Tom, you gotta quit relying on memory, LOL! You are showing early signs of "auldtimers disease", ha ha! He isn't asking about the '64 9770716 ("716" head).

The 76 Head is the '65 premium fuel high compression (10.5 advertised cr) head, not to be confused with the 421HO & GTO 77 head.

The 092 Head (I assume you mean the '66 092 when you say 92) is the '66 equivalent to the 76 ('66 421HO & GTO Head was the 093).

For Service Replacement, the '65 Heads apparently required some sort of fitting for the RH head, the '66 did not.

According to pg. 346 of the GTO Resto Guide, when the '66 Service Replacement 093 Head was used on a '65 GTO Engine, a specific lower center head bolt was required with an extended bolt head that allowed for proper torquing.

There is some other verbiage in the Guide that says that two different 093 Head castings were used in production, the one for Calif cars had a cast in internal air galley (for the AIR pump taps I assume).

It isn't stated, but since only one p/n was used for Service, it would seem to me only the casting with the AIR air galley was serviced.

This info is specific to the 093 Head in the Guide, but I suspect the same was true for the 092 Head. Reference to the Service News Flash 66-12, perhaps somebody with this document can check more closely. The incorporation of the air galley in the Service Head (along with production Calif Heads) may also be the reason why the special head bolt was needed for a '65 Engine.

Aside from these possible casting differences, the general features of the 76 & 092 head should be very similar or same. Same valves, springs, valve inclination angle, combustion chamber size, etc.

[rotdog]

Hay,Thanks for that. You guys are a WEALTH of information. Just got a 65 gp 389 engine with the 76 heads & 4 bbl intake, Where my 66 has the 093. Thinking on rebuilding the 65 with the 76 heads to put back in my 65 lemans.

[Tom Vaught]

Man, I missed the lack of the 1 in the 76 deal for sure, John.

Was trying to finish the post before dinner, LOL!

Sorry for the 64 INFO in the 65 thread.

Tom Vaught

[gto_ron]

Tom, John

I've been following this thread and the info is valuable. Tom, if the flow is about the same for most of the cast iron heads mentioned does that mean the larger valve sizes in the later heads(670 etc.) didn't really increase horsepower as one would expect?

thanks again for the info, I'm always learning

Ron
64 convertible

[John V.]

Tom and a lot of other guys on this Board can answer the flow question a lot better than me but here's my

The early heads were limited to a valve combo of 1.92/1.66. Some used even smaller valves, but I believe the GTO Heads along with heads like the 76 & 092 all had the same valve size.

The production of power difference was likely related to the chamber vol., cam selection, rocker arm ratio, and rpm potential.

The later 2.11/1.77 big valve heads likely benefitted from the larger valve sizes which was made possible by the revised valve inclination angle that began in '67 with the 670 head (most '67 heads remained close chamber with the old valve inclination angle, not til the release of the late '67 061 followed by the '68 heads did the first open chamber heads appear which all had the new valve inclination angle).

Perhaps they had higher power potential, but if they were limited to the same static compression, same cams, same rocker ratios, and same rpm limitations as used with the earlier heads, they likely did not take advantage of the potential the increased valve sizes could offer.

I think what I am trying to say is that air flow was not the limiting factor for stock engines.

The topic has always been too technical for my grasp and this is my basic understanding of it.

It would be interesting if somebody could explain how the bigger valves were useful to a stock engine (if they were) and then how they help with power potential in a non-stock build.

[Ken K]

Originally Posted by gto_ron

Tom, John

I've been following this thread and the info is valuable. Tom, if the flow is about the same for most of the cast iron heads mentioned does that mean the larger valve sizes in the later heads(670 etc.) didn't really increase horsepower as one would expect?

thanks again for the info, I'm always learning

Ron
64 convertible

There is a noticeable difference in performance switching to big valve heads. The big valve heads also have guide plates. The pushrod hole on the 1965 heads is smaller, it keeps the pushrod in place. Chevy small block heads of the same era used the small pushrod hole. Later model Chevy heads opened up the pushrod hole like the big valve Pontiac heads.

[Ken K]

Pushrod hole on a #76 head.

[Ken K]

Pushrod hole on a big valve head.

[Ken K]

Intake ports #76 head.

[Ken K]

Intake ports #16 head.

[dld]

The information below reflects the research conducted by Pontiac enthusiast/ author Pete McCarthy, much of which is from his book, Pontiac Musclecar Performance 1955-1977, as well as information gathered from many other Pontiac enthusiasts world-wide. Information about PMD heads is still being gathered. What is apparent is that while Pontiac had policies and specifications, both seemed to fluctuate as need be to build engines and place them in passenger cars.
Chamber size of heads is given as an approximate CC as is static compression. When examining any Pontiac head today it requires an open mind. All chamber sizes should not be assumed but cc'd to confirm the chamber size. I wish to point out that Pontiac manufactured heads with push-in studs and screw-in studs using guide plates. Most if not all performance heads used screw-in studs. Today machinists can easily improve on any stock iron Pontiac head with the inclusion of hardened seats, screw-in studs, longer valves, taller installed height for after market springs working with high lift camshafts.

Porting remains a viable means of improving flow for increased power. Most importantly, one must know the overall condition of the heads before attempting any performance modifications. Be sure to have them cleaned and magnufluxed by a competent machine shop.

If you have any information that may be useful in improving this head chart, please email me at: [email protected]

Year CID Advertised HP Head casting # Valve Sizes
intake/exhaust Approx CC or static CR
1959 389 215-345 hp 531395 1.88/1.60 69
1960 389 215-345 hp 536109 1.88/1.60 69
389SD 348-363 hp 535461 1.92/1.60 69
1961 389 all 538177 1.88/1.60 69
421 all 538177 1.88/1.60 69
389SD 368/373 hp 540306 1.92/1.66 68
421SD 368/373 hp 540306 1.92/1.66 68
1962 389 all 538177 1.88/1.60 69
421 all 538177 1.88/1.60 69
389SD 385/405 hp 540306/544127 1.92/1.66;2.02/1.76 68
421SD 385/405 hp 540306/544127 1.92/1.66;2.02/1.76 68
1963 326 250 hP 543797 1.88/1.60 8.6 cr
326 260/280 hp 548232 1.88/1.60 10.25 cr
389 215/230/235 hp 543796 1.88/1.60 8.6 cr
389 267/283/303/313 hp 543797 1.88/1.60 10.25 cr
421 320 hp 543797 1.88/1.60 10.75 cr
421 353/370 hp 9770716 1.92/1.66 72
421SD 390/405/410 hp 544127/9771980 2.02/1.76 64
1964 326 250 hp 9773345 (845) 1.88/1.60 8.6 cr
326 280 hp 9773395 1.88/1.60 10.0 cr
389 215/230/235 hp 5437796 1.88/1.60 8.6 cr
389 267/283/303/306 hp 9773345/(845) 1.92/1.66 10.5 cr
421 320 hp 9773345/(834) 1.92/1.66 10.75 cr
389 325/330/348 hp 9770716 1.92/1.66 72
421 350/370 hp 9770716 1.96/1.66 68
1965 326 250 hp 62 1.88/1.60 8.6 cr
326 285 hp 22 1.88/1.60 10.5 cr.
389 256 hp 75 1.88/1.60 8.6 cr
389 290/325/333 hp 76 1.92/1.66 10.5 cr.
389 335/338/360 hp 77 1.92/1.66 10.5 cr
421 338 hp 76 1.92/1.66 10.75 cr.
421 356/376 hp 77 1.92/1.66 10.75 cr
1966 326 250 hp 094 1.88/1.60 8.6 cr
326 285 hp 095 1.88/1.60 10.5 cr
389 256 hp 091 1.92/1.66 8.6 cr
389 290/325/333 hp 092 1.92/1.66 10.5 cr
389 335/360 hp 093 1.92/1.66 10.5 cr 68cc
421 338/350 hp 092 1.92/1.66 10.75 cr 70 cc
421 356/376 hp 093 1.92/1.66 10.75 cr 68 cc
1967 326 250 HP 140 1.92/1.64 9.2 cr
326 285 HP 141 1.92/1.64 10.5 cr
400 255/260/265 HP 142 1.92/1.64 8.6 cr
400 290 HP 143/061 1.92/1.64 10.5 cr.
400 325/333 HP Big Car 143/061 (closed chamber) 1.92/1.64 10.5 cr
400 350 HP (GP) 670/9787671/187 2.11/1.77 72 cc
400 325/335/360 HP 670 (closed chamber) 2.11/1.77 72 cc
400 325/360 HP RA 670/97 (closed chamber) 2.11/1.77 72 cc
428 360/376HP 670/9787671 (closed) 2.11/1.77 72 cc
1968 350 265 HP 17 1.96/1.66 8.6 cr
350 320 HP 18 1.96/1.66 10.5 cr
400 265 HP 14 1.96/1.66 8.6 cr
400 290/340 HP Big Car 15/215 1.96/1.66 10.5 cr
400 350 HP (GP) 16/ 216/ 62 2.11/1.77 72-75 ccs
400 330 HP (FB) 16/ 216/ 62 2.11/1.77 72-75 ccs
400 335/350/360 HP 16/ 62 2.11/1.77 72-75 ccs
400 335/360 HP RA I 31/ (37) 2.11/1.77 72 cc
400 340 (FB) /366 (GTO) R/96/ A (RA II) (rd port) 2.11/1.77 72 cc
428 375 HP 16/ 216 2.11/1.77 72 cc
428 390 HP 16/ 216 2.11/1.77 72 cc
1969 350 265 HP 47 1.96/1.66 8.6 cr
350 325 HP 48 2.11/1.77 10.5 cr.
400 265 HP 45 1.96/1.66 8.6 cr
400 290 HP 46 1.96/1.66 10 cr
400 340 HP (GP) 16/ 62 2.11/1.77 72 cc
400 330,335,350/ 366 HP 16/ 62/ 48 (MT) 2.11/1.77 72cc
400 345(FB) /370 (GTO) 722 (RA-IV) 2.11/1.77 71 cc
428 360 HP 16 (small-valve ) 46 1.96/1.66 10 cr
428 370 HP (GP) 62 2.11/1.77 72 cc
428 390 HP 16/ 62 2.11/1.77 72 cc
400 375 HP(RA-V) 44 Tunnel Port 2.11/1.77 67 cc
303 RA=V Tunnel Port 546184 2.11/1.77 56 cc
1970 350 255 HP 11 1.96/1.66 8.8 cr
400 265 HP 11 1.96/1.66 8.6 cr
400 290 HP 16 (small valve) 1.96/1.66 10 cr
400 330 HP Big Car 16 1.96/1.66 10 cr
400 330 HP 12 (MT) 2.11/1.77 72 cc
400 330 HP 13 (AT) 2.11/1.77 72 cc
400 345 HP(FB/RAIII) 12 2.11/1.77 72 cc
400 350 HP (GP) 13 2.11/1.77 72 cc
400 350 HP (GTO) 12 (MT) 2.11/1.77 72 cc
400 350 HP (GTO) 13 (AT) 2.11/1.77 72 cc
400 366 HP (GTO) 12 (RA III) 2.11/1.77 72 cc
400 370 HP (RA IV) 614 (Round Ports) 2.11/1.77 71 cc
455 360 HP Big Car 15 1.96/1.66 87 cc
455 360/370 HP (GTO/GP) 64 2.11/1.77 87 cc
1971 350 250 net HP 94 1.96/1.66 96 cc
400 265 net HP 99 1.96/1.66 98 cc
400 300 net HP 96 2.11/1.77 96 cc
455 280 net HP 98 1.96/1.66 114 cc
455 325 net HP 66 2.11/1.77 114 cc
455 335 net HP (455HO) 197(191) (Round Ports) 2.11/1.77 111 cc
1972 350 175 net HP 7H1 1.96/1.66 7.6 cr
400 200 net HP 7J2 1.96/1.77 8.4 cr
400 250 net HP 7K3 2.11/1.77 96 cc
455 200 net HP 7L4 2.11/1.77 114 cc
455 250 net HP 7M4 2.11/1.77 114 cc
455 250 net HP 7M5 2.11/1.77 114 cc
455 300 net HP(455HO) 7F6 (Round Ports) 2.11/1.77 111 cc
1973 350 150/175 net HP 46/4C 1.96/1.66 96 cc
400 170/185 net HP 46/4C 1.96/1.66 98 cc
400 200 net HP 4x/4C 2.11/1.66 98 cc
400 230 net HP (AT) 4X-7H screw-in studs likely 2.11/1.66 98 cc
455 215/250 net HP 4X-1H screw-in studs likely 2.11/1.66 114 cc
455 290 net HP (455SD) 16 (Round Ports) 2.11/1.77 111 cc
1974 350 155/170 net HP 46/4C 1.96/1.66 7.6 cr
350 200 net HP (GTO) 46 (screw-in studs) 1.96/1.66 7.6 cr
400 175/190 net HP 46/4C 1.96/1.66 8.1 cr
400 200 net HP 4X-4H/4C 1.96/1.66 99 cc
400 225 net HP (AT) 4X screw-in studs likely 2.11/1.66 98 cc
400 225 net HP (AT) 4C 2.11/1.66 98 cc
400 225 net HP (MT) 4X-3H screw-in studs 2.11/1.66 98 cc
455 215/250 het hp 4X-1H screw-in studs likely 2.11/1.66 114 cc
455 215/250 net hp 4C 2.11/1.66 114 cc
455 290 net HP (455SD) 16 (Round Ports) 2.11/1.77 111 cc
1975 350 ALL 5c/ 6X 2.11/1.66 7.6 cr
400 ALL 5c/ 6X 2.11/1.66 7.6 cr
455 AIR 6S 2.11/1.66 7.6 cr
350 HO non-air 6H 2.11/1.66 7.6 cr
1976 350 ALL 6X-4/ 6S 2.11/1.66 7.6 cr
400 ALL 6X-8/ 6S 2.11/1.66 7.6 cr
455 AIR 6S 2.11/1.66 7.6 cr
455 HO non-air 6H 2.11/1.66 7.6 cr
1977 301 ALL 01 1.72/1.50 8.2 cr
350 ALL 6X-4/ 6S 2.11/1.66 7.6 cr
400 180 hp 6X-8 2.11/1.66 7.6 cr
400 200 hp 6X-4 2.11/1.66 8.0 cr
1978 301 ALL 01/02 1.72/1.50 8.2 cr
350 ALL 6X-4/ 6S 2.11/1.66 7.6 cr
400 180 hp 6X-8 2.11/1.66 7.6 cr
400 220 hp 6X-4 2.11/1.66 8.1 cr
1979 301 ALL 01 1.72/1.50 8. 2 cr
400 220 hp (MT only) 6X-4 2.11/1.66 8.1 cr

[dld]

source ..... previous post is from Wallace race web site

[michaelroy]

How do these heads differ. 092, as I understand,were put on big cars and 093's on GTO's. If I exchanged 093's for 092's would I gain horsepower?