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Discussion Starter · #1 · (Edited)
I recently purchased a 1964 GTO project and in tearing down the front end sheet metal I found this. It looks like an add on fresh air intake. I don't remember anything like this when I worked at a Pontiac dealership in the early 70s. I just want to confirm it is not some kind of option or dealer addon. Anyway the drivers side hose attachment is missing and the hole is where the trim tag goes. I found the trim tag in a box of paper work I got with the car.
 

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Interesting. Maybe you have a "special" former factory race car? If I had to guess, someone may have been pulling air off the windshield and feeding it into the air cleaner or tri-power top.

Check out these factory tri-power air cleaner assemblies. Some one being creative might turn the snorkels backards to face the firewall and then connect a few hoses to the "removed" snorkels that are now bolted to the firewall cut outs - might be something I might fabricate.

 

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I found this write up.


Hood Motor vehicle Automotive lighting Automotive fuel system Automotive design





By 1964 when the Pontiac GTO was introduced, General Motors was officially out of the organized racing game, but the Pontiac division continued to maintain less formal ties with the performance community— for example, through Royal Pontiac in suburban Detroit and its resident performance wizard, the late Milt Shornack (1935-2020). Sizing up the twin, broadly spaced fake hood scoops on the ’64 GTO, Shornack found them unsuitable for conversion into working intakes, so he adopted the Chevy-style system above. This setup was installed on the Car and Driver magazine ’64 GTO road test car, an infamous ringer prepared by Royal Pontiac. (Shornack’s book, Milt Shornack and the Royal Bobcat GTOs, as told to Keith J. MacDonald, is a worthy read.)
 

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Discussion Starter · #6 ·
Interesting. Maybe you have a "special" former factory race car? If I had to guess, someone may have been pulling air off the windshield and feeding it into the air cleaner or tri-power top.

Check out these factory tri-power air cleaner assemblies. Some one being creative might turn the snorkels backards to face the firewall and then connect a few hoses to the "removed" snorkels that are now bolted to the firewall cut outs - might be something I might fabricate.

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Well I think it is kind of special, I have been after this car for over ten years. Finally got the owner to part with it. It is a Tripower, 4 speed car, although not numbers matching. I would like to do a 389 since I have an early TP setup but can't find an early head that would give me between 9 to 10 to one compression.
 

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I found this write up.


View attachment 159320




By 1964 when the Pontiac GTO was introduced, General Motors was officially out of the organized racing game, but the Pontiac division continued to maintain less formal ties with the performance community— for example, through Royal Pontiac in suburban Detroit and its resident performance wizard, the late Milt Shornack (1935-2020). Sizing up the twin, broadly spaced fake hood scoops on the ’64 GTO, Shornack found them unsuitable for conversion into working intakes, so he adopted the Chevy-style system above. This setup was installed on the Car and Driver magazine ’64 GTO road test car, an infamous ringer prepared by Royal Pontiac. (Shornack’s book, Milt Shornack and the Royal Bobcat GTOs, as told to Keith J. MacDonald, is a worthy read.)
That is correct. The red '64 Car & Driver GTO had a similar setup that was designed by Shornack. After many runs/tests, it was determined that it made little to no difference. The set up was removed and a plate was put over the opening on the firewall. If my memory serves me correctly, Milt kept the same huge Tri-Power single air cleaner used in the experiment up until the car was sold in the 90's. I know for a fact they did not use the 3 individual air cleaners . When >>in my opinion<<, an unnecessary restoration that should have never of been done on that historic original vehicle, they covered up and eliminated the experimental "ram air/fresh air" history on the firewall and now you wouldn't even have known it was there. Pontiac history destroyed! I do know there is nothing telling that historic GTO today from any other "run of the mill" '64 GTO that has been restored. Put it side by side w/ another restored '64 red GTO and you won't be able to tell which one is which.
 

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That is correct. The red '64 Car & Driver GTO had a similar setup that was designed by Shornack. After many runs/tests, it was determined that it made little to no difference. The set up was removed and a plate was put over the opening on the firewall. If my memory serves me correctly, Milt kept the same huge Tri-Power single air cleaner used in the experiment up until the car was sold in the 90's. I know for a fact they did not use the 3 individual air cleaners . When >>in my opinion<<, an unnecessary restoration that should have never of been done on that historic original vehicle, they covered up and eliminated the experimental "ram air/fresh air" history on the firewall and now you wouldn't even have known it was there. Pontiac history destroyed! I do know there is nothing telling that historic GTO today from any other "run of the mill" '64 GTO that has been restored. Put it side by side w/ another restored '64 red GTO and you won't be able to tell which one is which.
The testing is really inconclusive because a narrow parameter was used in testing - drag racing down a strip on that day with those weather conditions.

It is not about the "ram" effect of the air which requires high speeds to make such a thing usefull, BUT, bringing in cooler denser outside air into the carb/engine. With the cooler air, Milt was able to increase jetting ad thus increase power. So the open scoop or pulling air off the windshield is not necessarliy about forced air and more HP, but cooler denser air that allows for an increase in the jetting which translates to more HP.


"These first scoops relied on the “boundary layer” principle. With this arrangement, the opening of the scoop wasn’t flush with the top of the hood. Instead, the inlet was raised slightly to account for the air flow passing over the nose and hood of the car. A scoop with an opening flush with the hood surface was essentially mounted in dead air. Placing the scoop in direct line with moving air improved the “ram” factor.

Chrysler’s findings: If the opening of the scoop was too large or too near the actual base of the hood, then the air would “stack up.” In effect, the air actually pushed backward against the floor and out of the scoop opening.

“For every 10-degree increase in air temperature, there is a 1-percent decrease in horsepower. The air under the hood of a typical street car is heated by the radiator, exhaust system, and engine. In contrast, a hood scoop supplies outside air at ambient temperature. The difference in output between a Pro Stock engine inducting 100-degree air and the same engine running on 60-degree air is approximately 4 percent, or about 48 horsepower.

“The amount of pressurization produced by a hood scoop varies as a function of the square of the speed of the vehicle. The formula for calculating pressure is:

0.0000176 x air speed in mph² = ram pressure increase in pounds per square inch (psi).

If you plug in the numbers, you’ll find an increase in inlet air pressure of .142 psi at 90 miles-per-hour. Standard atmospheric pressure is 14.7 psi, so this represents an increase of just under 1 percent. If the air/fuel ratio is adjusted to compensate for the increased pressure, there should be a corresponding 1-percent increase in horsepower. For a 1,200-horsepower Pro Stock engine, that’s a gain of 12 horsepower. Hood scoop pressurization increases dramatically at faster speeds: It’s 2 percent at approximately 130 miles-per-hour, and 3 percent at 158 miles-per-hour. At the magical 200 mile-per-hour mark, the theoretical pressure increase is .704 psi, or 4.8 percent. That equals 56 “free” horsepower.

Unfortunately in racing, just as in life, there is no free lunch. The penalty you pay for this increase in inlet air pressure is the extra aerodynamic drag produced by the hood scoop."

 

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Discussion Starter · #10 ·
You don't use the head to drop compression, use dished pistons.
That is what I have been able to determine on the 64 and earlier engines, not like the 67 and up head selection with different chamber sizes. I wanted the engine to look like a 64 engine and to use the parts I already have, a 64 389 block with the new .030 over 389 pistons and 64 Tripower I happen to have on hand. Anyway that was my reasoning for looking for larger chamber heads for the early valve angle engines. I know that Pontiac didn't build all 10.75 compression engines in the 389 engine lineup and all I have seen used flattop pistons so they must have varied the combustion chamber.
 

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That is what I have been able to determine on the 64 and earlier engines, not like the 67 and up head selection with different chamber sizes. I wanted the engine to look like a 64 engine and to use the parts I already have, a 64 389 block with the new .030 over 389 pistons and 64 Tripower I happen to have on hand. Anyway that was my reasoning for looking for larger chamber heads for the early valve angle engines. I know that Pontiac didn't build all 10.75 compression engines in the 389 engine lineup and all I have seen used flattop pistons so they must have varied the combustion chamber.
Be aware that 1964 and earlier heads (1964 was the change over) used oiling through the rocker arm studs.

Most all Pontiac pistons are flat tops with a couple exceptions on earlier engines were a small dish is used to drop compression because only 1 head was used across the board.

I am showing for 389 engines with 8.6 compression; 1964 used head # 543796, 1965 - "75', 1966 - "091". I don't know exactly what the chamber volume is, but best I could find was a mention of 90 CC's.
 

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Discussion Starter · #12 ·
Be aware that 1964 and earlier heads (1964 was the change over) used oiling through the rocker arm studs.

Most all Pontiac pistons are flat tops with a couple exceptions on earlier engines were a small dish is used to drop compression because only 1 head was used across the board.

I am showing for 389 engines with 8.6 compression; 1964 used head # 543796, 1965 - "75', 1966 - "091". I don't know exactly what the chamber volume is, but best I could find was a mention of 90 CC's.
That is what I came up with on the 63-64 heads. Most internet head charts regardless of who publish them are the same they switch from cc's to compression ratio. The 65 and 66 heads would be out because of the 5 bolt intake pattern. I guess I will have to find a set of 796's or the 8.6 equivalent to measure the chamber. I just want to be able to raise the hood and it look like it was assembled in 64. Thank you for your knowledge and impute on this little dilemma.
 

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That is what I came up with on the 63-64 heads. Most internet head charts regardless of who publish them are the same they switch from cc's to compression ratio. The 65 and 66 heads would be out because of the 5 bolt intake pattern. I guess I will have to find a set of 796's or the 8.6 equivalent to measure the chamber. I just want to be able to raise the hood and it look like it was assembled in 64. Thank you for your knowledge and impute on this little dilemma.
OK, sounds like a plan. Here is a little more info that might be of some help:

 
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