[mgarblik]

Originally Posted by jhein

The question is, why? I'm sure someone here knows. Something about the fit of the Formula air cleaner assembly on that particular configuration? But in 73 those weren't functional, right? So that's probably not it. The shaker was also not functional in 73, but easier to convert than the Formula setup. Could that be it, easier to convert to functional? Somehow, I doubt that too. I'd love to know though.

Here is an educated "guess" as to why the SD-455 cars had the shaker regardless of whether in a TA or Formula. To meet EPA emissions certiifications, the engine is treated as an "engine package", with all equipment as installed on the engine including the air cleaner. The shaker scoop, functional or not, must have been included as part of the engine package. Therefore, to install the SD-455 in a Formula without the scoop, a separate EPA Certification would have to be obtained for that "different", engine package. I know it sounds stupid, but I bet that played into the reasoning for just installing the few SD formulas with the shaker hood. It takes several days of testing and costs thousands of dollars to certify each "engine package" This is another reason so few cars are available with manual transmissions today. They also require separate certifications from automatic versions of the same engine. Now referred to as a "powertrain package including final drive ratio" Hope this makes some sense.

[jhein]

Originally Posted by 71GP76TA

There's a silver SD Formula sitting in my garage.

Obviously, there are lots of folks here that have super cool rare cars, but, I'm particularly fond of TAs and Formulas. That is just cooler than cool that you have that car. I'm jealous. Makes mine seem like a cold McDonald's hamburger with a dried up, crooked bun. LOL.

[bird72]

I believe the SD would have required EPA recertification with the Formula / RA set up, may not have met noise standards. Easy out was stick the TA hood on the Formula as already certified. Correct me if my memory is off. The 73 boarded up shaker is part of this story also, I believe.

[jhein]

Originally Posted by mgarblik

Here is an educated "guess" as to why the SD-455 cars had the shaker regardless of whether in a TA or Formula. To meet EPA emissions certiifications, the engine is treated as an "engine package", with all equipment as installed on the engine including the air cleaner. The shaker scoop, functional or not, must have been included as part of the engine package. Therefore, to install the SD-455 in a Formula without the scoop, a separate EPA Certification would have to be obtained for that "different", engine package. I know it sounds stupid, but I bet that played into the reasoning for just installing the few SD formulas with the shaker hood. It takes several days of testing and costs thousands of dollars to certify each "engine package" This is another reason so few cars are available with manual transmissions today. They also require separate certifications from automatic versions of the same engine. Now referred to as a "powertrain package including final drive ratio" Hope this makes some sense.

That does makes a lot of sense. If you watch the video below, the dude talks about how they got around EPA requirements for a "new" engine, so maybe that's it. Although, he does say that they got around the EPA because the 455 was an existing platform that already went through testing. If that's the reason, then the fact that they had already offered the 455 with the Formula hood should have made that OK, no? But, that stuff was complicated and political so who knows.

https://www.youtube.com/watch?v=e9UtMwJ9m1U

[johnta1]

As Mike said, it was for EPA testing.
The late introduction of the SD engine (SD heads mainly and cam probably), required it to pass a certification test. There was not enough time to get it certified with the Formula hood, so since the TA hood had been tested, they used the TA hood on the Formula.
It's well documented, don't have the facts in front of me at this moment though.

[71GP76TA]

Originally Posted by jhein

Obviously, there are lots of folks here that have super cool rare cars, but, I'm particularly fond of TAs and Formulas. That is just cooler than cool that you have that car. I'm jealous. Makes mine seem like a cold McDonald's hamburger with a dried up, crooked bun. LOL.

I had a '70 4 speed T/A that I regretfully sold last summer.. It ended up getting replaced with a '75 T/A.... which is just a pacifier for now..

[johnta1]

(SD heads mainly and cam probably)

I think the exhaust manifolds (round ports) may have been a reason also.

[necdb3]

Originally Posted by johnta1

As Mike said, it was for EPA testing.
The late introduction of the SD engine (SD heads mainly and cam probably), required it to pass a certification test. There was not enough time to get it certified with the Formula hood, so since the TA hood had been tested, they used the TA hood on the Formula.
It's well documented, don't have the facts in front of me at this moment though.

I remember reading it was for certification of noise levels. The noise levels were the reason the functional shakers went away for 73. The shaker hood was tested with that engine, the Formula hood was not. I don't think they wanted to recertify that engine with a different induction system for cost purposes.

[johnta1]

That was also my thought. (but didn't write it down)

The different SD equipment required testing because it was different than the d-port 455 setup.
With the EGR change it probably delayed a lot of things. Along with the late introduction of the SD engine.

I'll have to look for the docs.

[jhein]

Originally Posted by necdb3

I remember reading it was for certification of noise levels. The noise levels were the reason the functional shakers went away for 73. The shaker hood was tested with that engine, the Formula hood was not. I don't think they wanted to recertify that engine with a different induction system for cost purposes.

I've read the same about the shaker and the noise level. I've never heard any explanation for why the Formula lost the functional scoops.

The thing that's confusing me is that what you and others have said about needing testing for different induction systems makes total sense, but in 73 neither the shaker scoop or the Formula hoods were functional. So they weren't actually part of the induction system. I guess technically they could have considered the shaker to be just because the "scoop" (that's not actually a scoop) was physically attached to the air cleaner assembly. But the Formula hoods were not.

[jhein]

OK, so I just found this: https://tran-zam.com/history/1973/Facts.htm

This person concludes that because the parts were, or may have been, available that the factory option was also (possibly) available. He still has ifs, buts and maybes in there though.

"Formula Twin Snorkel Hood
Whether the Formula Hood Scoops could be mad efunctional from the factory is a controversial topic. Both The Fabulaous Firebird by Michale Lamm and Firebird, America's Premiere Performance Car by Gary Witzenberg say that all hood scoops were closed beginning in 1973 but option 634/WU3 listed Ram Air Hood as available for 400 and 400 equipped Formula's. It is not unusual for Pontiac to cancel options if regulation were involved as it was for the Trans Am (Trans Am could not meet Federal noise emissions standard with a functional scoop) but in this case it was probably not. Pontiac parts manauls show Hood part number 490661 as RAM AIR EXC SHAKER HOOD - W/FUNCTIONAL SCOOPS as available up to 1975. The same parts manual shows RAM AIR Decal part numbers (black or White) available until 1974. It is tehrefore determined that the 634/WU3 option was valaid for 1973.

Note that since the Formula with the SD-455 engine shared Trans Am's shaker hood scoop the SD-455 could not be ordered with a functional scoop. The Trans Am with a standard 455 engine would have a closed shaker as well so it is possible that a Formula ordered with the optional 455 engine and functional scoops may have had more horsepower than a TA."

[Old Goat Racer]

I bought this book in 1973 when I was car shopping. I bought a used 1970 Lucy Blue TA for $1700 instead.

The prices were staggering.

$675 for the SD engine.

The book also list the SD engine for the LeMans/GTO and Grand Am BUT the factory never made that ?? LOL

[ta6point6]

Speaking of factory or not, I had seen this on my local craigslist

[Chief of the 60's]

Originally Posted by ta6point6

Speaking of factory or not, I had seen this on my local craigslist

I believe Superior did them. They're called an Airport Limo.

[GT182]

As I understood it, the shaker hood scoop was also blocked off for the 455-Formula SD. Not open at all from the factory, just like it was closed for the normal 455 TA.

Read just below the photo of the SD 455 shaker hood scoop.....

https://www.hemmings.com/stories/art...rans-am-sd-455

What exactly is this 634/WU3 option? Open hood scoop? As for the Formula's open hood scoops, the "standard" 400 engine, Formula scoops were available open as an option or closed from the factory. Not sure what year allowed the option of "open". I never got into the earlier Formula Firebirds because I didn't really care to the looks of them with hood scoops, and I couldn't afford one anyways. It wasn't until 1979 that I was struck by the Formula Firebird and it's looks. I still don't know if even that year and 1980 Formulas could come with open scoops or not.

That Trans Am.com link sure is missing info on Formulas with the WS6 package [of which my 1979 Formula was one of them], and other info pertaining to the Trans Ams thru to 1981.

[bird72]

While I love and have had Ram Air, I personally believe it is barely negligible in added HP. adding an open element air cleaner probably equals adding factory style RA. Flame away!

[Old Goat Racer]

In my Edmonds book the 634 code (Ram Air Hood) is listed for the 400 and 455 engines on the Formula for $56

[johnta1]

I think the twin scooped hood was available with the open scoops only for the Formula with 400 4 bbl engine in 1973 and 1974.
The 'TA' hood was used for the SD 455 engine.
On the PHS it would show a credit for the hood being non-functional.

I show the price as $56 for the Ram Air hood.

[Old Goat Racer]

Originally Posted by johnta1

I think the twin scooped hood was available with the open scoops only for the Formula with 400 4 bbl engine in 1973 and 1974.
The 'TA' hood was used for the SD 455 engine.
On the PHS it would show a credit for the hood being non-functional.

I show the price as $56 for the Ram Air hood.

You are correct John. I need thicker glasses.

[Tellyshavilli]

Originally Posted by necdb3

I don't think that's the same car. Steve bought that car out of Canada. Bob bought it from Steve. Unless the buyer shipped it to Canada. I owned a 72 F455 cardinal red/ black 4spd with air back then also.

You’re right it’s not the same car there was a different one in Jersey