[track73]

I'm thinking of changing the intake on the Trans Am since I don't race the car and turned it into a cruiser. I own 4 cast iron q jet manifolds. They include a '68 '70,'72, and '79. The '72 and '79 would fit the 96 heads. The 72 is awful heavy and the '79 looks restrictive with the D shaped secondaries. I know about blocking the crossover port, but I'm a little hesitant. Would the EGR '72 manifold work by just blocking the EGR port and would the weight make any difference, besides hurting my back installing it?

[Jim Moshier]

I have heard that the stock cast iron intake all flow pretty much the same even the 1979 intake with the EGR valve flowed pretty good even with the D-shaped secondaries. I have noticed the early ones seem to be a bit taller and the later ones a little short....it may be just a visual perception as they have more material around them. I have a 1969,1971 and 1979 intake and would not hesitate to put it on and run it as is, and I think the 1968-1969 look the best. I dynoed my new motor and the stock 1969 intake gave up nothing to the Edelbrock RPM running a re-worked QJ and the Edelbrock AVS-2 both 800cfm. JMO
Jim

[Kenth]

All of your intakes will fit your #96 heads equally well, just use 1972 and later intake gaskets for 1972 and later intakes.
The 1972 intake is the same weight as the earlier siblings.
1973-74 EGR intakes with the deep EGR channels are the heaviest and require corresponding valley covers.
With all this said i would use the 68 or 70 intake on your #96 heads.

FWIW

[grandam1979]

Your not going to feel a big difference between the two intakes on the street. When I had my 80 t/a setup a lot like your car 455 6x heads 9.5 comp. 3.42 gears I went the other way from a dual plane to a HSD the car picked up .2 and 1-2 mph with no other changes. I know everybody thinks all your bottom end is gone with the single plan and with a stock converter it would be true with a stall 2400 up not so much. With all that said your running the Rhoads lifters so the dual plan might help your bottom end running the highway gear.

[74Grandville]

not sure choke is a concern, but you may want to base it on that as well. if electric, i would swap in the 72 and sell the rest. keep that HSD, you may want to reinstall someday. the 72 intake works with early and late heads.

[Baron Von Zeppelin]

The "later" 68 intakes (ending in #234) are better than the earlier 68's.
The 70 intake was tested/flowed as supposedly flowing the best of them all.
By best - it was slim margins on all of them.
Even the EGR and 3/4 port late models.

Check your month/year on the Intakes , the one you call 72 sounds like a 73 production.
72 didn't have EGR

Your 68 - might be a 69 Production (also ends in #234)
Your 70 - might be a 71 - depending on Month it was cast.

Your 79 - was likely cast in early/mid 1978, those were done for the 1979 400 T/A's only, and held back for them to use on the W72 cars only.
Everything else in 1979 was 301 P. or 305 C. or 403 O.

[Baron Von Zeppelin]

The exact dates - and the part numbers - from your Intakes will tell us what you actually have. To make the best choice.

Off the shoulder i think the 1970 Intake part number ends in #068

[77 TRASHCAN]

I was also wondering if the 72 intake was a 73 design, cast in 72. 73 was the first year for EGR.
The true (non EGR) intakes are nice, for the exhaust crossover holes lining up without modifying anything when using 72-up heads.
I emailed Dave Bisschop, years ago about the last EGR intakes, approximately 1975-1979. He related to me they were as good as the earlier units. I don’t know about the deep sump units, though...

[Rocky Rotella]

I’ve had a large variety of 67-78 (and 79 400) cast iron 4bbl intake manifolds on my flow bench. At least a couple of every type, meaning 67, 68-72, 73-74, and 75-79.

I can say with absolute certainty that in as-cast condition the flow differences between the factory cast iron units is marginal. This obviously excludes the 73-74 SD-455 unit.

The last units Pontiac produced in the late 70s were the very best from a production quality and consistency standpoint.

From a performance standpoint, I might suggest one goes with whatever manifold has the features that best fit their application. Those features include exhaust crossover size, choke heat source, throttle linkage bracket type, deep or shallow valley pan, and the position of the rear AC bracket mounting boss (if AC is being used). And if EGR is required for emissions inspection, then one must consider that too.

In the end, run what you have that will fit your application and from the drivers seat you and your engine will never know the difference!

[Slick]

Fel Pro 1233 intake gasket set allows the use of a pre-72 intake on a 72+ set of heads without exhaust crossover issues. Optional inserts are provided for blocking off or leaving open the crossover without leaks.

I have personally used them a couple of times now with zero issues.

https://www.summitracing.com/parts/f...3/make/pontiac

Stuart

[Formulas]

Myself I like the open webbing around the exhaust crossover on the 68
As I usually block off the crossover combined with open webbing there is less of a metal path to conduct what heat there still is

Just personal preference

Point of interest

One night when I had my 68 GTO I had the crossover blocked I got off the freeway quickly pulled into a parking lot got out engine still running touched some intake runners and they were very cold mild summer night

[Slick]

Originally Posted by Formulas

Myself I like the open webbing around the exhaust crossover on the 68
As I usually block off the crossover combined with open webbing there is less of a metal path to conduct what heat there still is

Just personal preference

Point of interest

One night when I had my 68 GTO I had the crossover blocked I got off the freeway quickly pulled into a parking lot got out engine still running touched some intake runners and they were very cold mild summer night

Completely agree about the crossover!