Cehbra

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This thread is for thirdgen enthusiasts (like myself), who love that famous asymmetrical hood from the third generation Firebirds.

My very first car was a red 1982 LG4 Trans Am. Just for nostalgia and the looks I wanted a bulge hood for my 1991 LO3 TBI Firebird. So I treated myself to one from a carbed 1984 Trans Am. At first I neglected the plastic box that was mounted inside the bulge. But as time went by I got interested in that thing sitting on the shelf and subsequently read into cowl induction. That’s when I decided to fit that system into my Firebird.

And then I thought I learned so much from dweling on TGO that in return I should post the knowledge I have gathered over time so that it wouldn’t get forgotten. Of course, much of what you’re going to read here has been posted before. But there are some things I found out myself in the process, too.

And heck - just for the love of it - here are my $ 0.02 on the topic. And it is gonna be a looooong post !

Look and enjoy, comment and complain!

Part 1: Short (long) history of the power bulge hood
Part 2: Tech bits on (factory) cowl induction
Part 3: Parts needed
Part 4: Fitting cowl induction to LG4/L69/LO3

Disclaimer: most of the pictures are my own. And some were taken from other sites and the copyright belongs to them.

Cehbra

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Part 1: Short (long) history of the power bulge hood

Introduction
In 1982 Pontiac simply called it “sport hood”. Others reference it by “cowl induction hood”, which was true for 1982-1984 / early thirdgens. After that it was frequently called “Formula hood” because it was used on the 1987-1992 Formulas. Then again a popular name is “power bulge hood”, named like that for obvious reasons. I also like “turbo hood”, as it refers to its original intention of carrying the design of the 1980/81 Turbo Trans Am into the third F-body generation, although without the turbo. Anyway, it remained the same hood throughout the whole third generation.



My power bulge hood – still dented and covered with many layers of non-factory paint

Cehbra

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Side track on second generation Firebirds: the 1980/1981 Turbo Trans Am
The Turbo Trans Am 4.9L introduced the turbo hood, making it the first Trans Am since the 69's to not have a shaker hood. The hood had about a 22 inch bulge that extended upwards 1.25 inches and was offset to the left of the hood centerline.



1981 Trans Am Pontiac 400 Turbo with turbo hood. © www.restoreamusclecar.com

Clearance for the relocated carburetor and plumbing from the turbocharger made this bulge necessary. Meaning: it wasn’t used for cowl induction.



The conventional carb is offset to the right and the turbo to the left, on top of the engine. © www.restoreamusclecar.com

To make things a bit more interesting, a "turbo boost gauge" (RPO UR4) could be ordered for $40 and consisted of a series of three orange lamps which were located at the rear of the bulge facing the driver. The three lights that illuminated in sequence as the turbocharger’s boost pressure rose were just a gimmick. But one with a high coolness factor!



The trailing edge of the Firebird Trans Am Turbo’s hood bulge contains this rudimentary “boost indicator”. © ateupwithmotor.com/model-histories/pontiac-trans-am-turbo

Cehbra

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Third generation Trans Am: the early years 1982 - 1984
The 1982 turbo hood was originally developed to be used with the Pontiac 4.9L turbo engine from the 1981 models. Sadly GM gave it the axe and Pontiac was to only use the Chevrolet V8 power plants in the Trans Am until 1989. Since the change in the engine program was so late, they didn't have time to change the design of the hood for the 1982 Trans Am. But fortunately, the hood bulge remained and was even made functional later in 1982.

Engine / hood / cowl induction options available in the early thirdgens
There were several hood/CI combinations available in 1982-1984:

• Flat hood, no cowl induction
• Turbo hood, no cowl induction
• Turbo hood with cowl induction, i.e. functional

The following table lists the engines that were available in 82-84. Options where functional cowl induction was obtainable are marked green (data from GM/Pontiac sales brochures and Firebird manuals):

Green: functional cowl induction available (or mandatory for LU5)
S = standard option
A = available option
1 downgrade option

Basically the turbo hood could not be ordered on a base Firebird or Firebird S/E, not even with an LG4 engine upgrade. So in the early third generation the turbo hood always indicates a Trans Am. But the inverse isn’t true – at least not for 1982 – as there were (although not many) Trans Ams sold with the flat hood.

Cehbra

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LG4: the carbureted 4 barrel 5.0L V8 engine was the standard option for a Trans Am and could not be downgraded. Interestingly, standard in 1982 was the flat hood on LG4 Trans Ams, but you could option a Trans Am LG4 with the – initially – non-functional Turbo Hood as an appearance upgrade. The hood would be sealed with a block off plate. Adding WS6/WS7 did not automatically add the turbo hood but WS6/WS7 was mandatory to get it as the two options were paired. The functional induction turbo hood for the LG4 did not appear until somewhere around mid/late 1982. So most of the 1982 LG4 cars have a non-functional hood, but there are some late 1982 Trans Ams with a functional cowl induction setup. Yet still in 1983/84, all Trans Ams with the LG4 also came standard with a non-functional turbo hood, however not the flat hood. The functional turbo hood was an option, and most cars were also ordered with it. But LG4 Trans Ams with the non-functional turbo hoods do exist for 1983/84... not common, but they are out there.



My first car – 1982 LG4 with non-functional turbo hood, scoop has honeycomb mesh

LU5: In 1982 the new fuel-injected crossfire 5.0L V8 power plant was available as an upgrade option for the Trans Am exclusively. The LU5 was retired midway through 1983 and replaced by the carbureted L69 HO 305. All crossfire Trans Ams had the functional turbo/cowl induction hood mandatory and all came with WS6/WS7. The LU5 cowl induction setup differed from the LG4/L69 in shape and actuator, see later.



LU5 crossfire engine with double air filters (don’t remember where I got that picture from, sorry)

L69: When the LU5 crossfire was dismissed mid/late 1983 it was replaced with the carbed L69 which used the exact same air cleaner as the LG4. Until the end of the 1984 production year all L69 had functional cowl induction and therefore the turbo hood. That changed in 1985 when cowl induction was scrapped entirely for all third generation Pontiac F-bodies. The L69 continued to live until 1986, but without the cowl induction setup.



L69 engine bay with open air cleaner © http://www.hotrod.com/cars/featured/...ntiac-trans-am

Cehbra

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The Formula years 1987 - 1992
The power bulge hood wasn’t available from 1985 to 1986. It didn’t make its reappearance until 1987 when the Firebird Formula was reintroduced. I can only speculate on the reasons Pontiac made that choice. I guess that customers simply demanded it. The hood was the same as on the 1982-84 Trans Ams, only it had been sealed off. So there was no solenoid activated hood scoop and no open air cleaner assembly. The power bulge hood had been relegated to pure decoration. Back then tuned port injection engines were introduced and they couldn't use the cowl induction system – at least not without major reworking of the intake and induction system. So the cold air induction system was scrapped. With the coming demise of any carburetor engine in the GM lineup, a functioning cowl induction system sadly didn't really make sense either mechanically or economically. Still, theoretically the later 5.0 liter TBI injected small block cars like the LO3 could benefit from a cowl induction setup – that’s what this post is all about.
It is said that the first production 1987 Formulas received leftover stock hoods from 1984. Subsequent cars were provided with newly produced hoods that were punch pressed on the original molds but with thinner sheet metal. So at some point after 1987, the hoods became lighter and maybe a bit flimsier, too.



© 1987 Pontiac Formula 350 Showroom Picture Brochure

Hope you enjoyed it so far... Stay tuned for part 2: Tech bits on (factory) cowl induction

((Mike))

iTrader: (1)

Thanks for making this post. I never knew anything about the TAs. What did the functional crossfire TA hoods look like? Did they have reverse facing flaps like the 80-81 air induction Z28s? If you have a photo of the TA LU5 hood I would like to see that setup. Thanks again!

Cehbra

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You're welcome. The LU5 version came with the same exact hood as the LG4/L69. However the air duct inside the bulge was different. I'll post up more later... busy at work right now

PurelyPMD

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Subd.

dmccain

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When I first got my car the previous owner had installed the lil air induction off an 83 HO car I believe. A switch was installed to open the flap to let the cool air in the lil donut hole on top the breather sealed to a duct. I sold it to someone on this website who needed it for a restoration. I did not like the look of it

dmccain

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The middle picture is the air cleaner to the cowl induction setup.

chazman

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Cehbra

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Back from work.

Thanks for the comments, pals!

Let's move on to the second part...

Cehbra

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Part 2: Tech bits on (factory) cowl induction

General
When the laminar air flow over the hood hits the windshield, turbulences develop and an air flow in the opposite direction is formed at speeds > 35 mph (55 km/h). Thus by opening the reverse scoop on the hood, cold air can be inducted into the engine. The air from inside the engine compartment is hot (often 140 – 200°F), but cold air holds more oxygen. More oxygen – more power. Plus a „forced“ - that’s a strong word here - induction could theoretically provide even more power. A poor man’s supercharger, so to speak.

There was the April 1987 issue of Popular Hot Rodding which included the article "Fresh Air Induction For Budget 'Bird" by Jim Losee. It states that […] These same ideas can be used to increase the power of today’s computer controlled GM cars that come equipped with a carburetor. Because the computer control system has a built in +/- 15 percent variability factor, as long as we don’t go overboard with how much fresh air is inducted into the carb, there should be an increase in power without causing a problem with the computer control system. A subsequent benefit of fresh air induction is an increase in fuel mileage […]. When they tested their Firebird on the chassis dyno it showed an increase of respectable 18 rwhp!

Cehbra

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Air duct mechanics
To duct air through the hood scoop and into the engine Pontiac designed a two-piece setup. First there is the hood-side piece that consists of the “airbox”, as I call it. This plastic element guides the air from the vertical scoop to a horizontal opening. A solenoid activated flap is mounted inside the box, more on that later. The engine-side piece consists of an open air cleaner assembly. When the hood is closed, both parts are adjacent and a silicone gasket seals the induction unit. There are several drains and slopes on the airbox to prevent water from entering the air cleaner.

LG4/L69 vs LU5 version
The air cleaner from the carbed LG4 and L69 has a round lid with an off center circular 4.3“ opening. That hole was encased with a silicone ring. The air cleaner from the LU5 crossfire setup is different and contains two small air filters and a non-encased diamond-shaped opening. The seal was attached to the airbox, which also had a diamond-shaped opening. In both versions the solenoid that opens the flap is mounted at the side of the airbox. On the carbed cars it is activated by a series of probes and switches (described later). On the crossfire cars the ECM controls the solenoid.

Cehbra

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Electrics
Most of the effort that went into the cowl induction setup really is about operating the solenoid/flap at just the right time to get the air into the engine exactly when needed, but keep the box closed the rest of the time. Here is a detail of the diagram from the 1984 Firebird owner’s manual.



If not in use - the flap inside the air box is meant to stay closed. As the hood is above the engine, rain and dirt could enter inside the carb. Some hydrolocked engines have been reported when the flap is constantly open. There really is only one situation where the scoop flap should open up: when extra oxygen is needed and that is only at wide open throttle. At WOT, manifold vacuum drops and that is what can be sensed with a simple vacuum switch off a vacuum line beneath the air cleaner.

So when vacuum drops, the switch should close and activate the hood solenoid. Naturally we therefore need a vacuum switch that (electrically) is normally closed (NC) and is open at vacuum. Unfortunately there is one drawback: when the engine is not running (key in run) there is no vacuum as well, and so the switch is conducting and activating the solenoid – discharging the battery and potentially damaging the solenoid. To make sure that the solenoid can only be activated when the engine is running, Pontiac engineers ran the power through the oil pressure switch first (which is closed only when the engine is running, obviously).

As can be seen in the diagram there is yet third switch, a so called “cold override switch” in between the oil pressure switch and the vacuum switch. The purpose of that probe - according to the 1984 Pontiac Firebird Service Manual - was that without the switch when the engine was cold, if you hit full throttle, the scoop flap would open up and let all that cold air in and the engine could stall. So that temperature switch simply prevents the flap to open when the engine isn’t properly warmed up to at least 140°F (60°C).

It’s all that simple! As I mentioned, in the LU5 cross fire engine the system does not work that way. There the solenoid is controlled by the ECM and that is a totally different thing not covered in this article.

Cehbra

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Anyone care for part 3? Coming right up anyway

Cehbra

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Part 3: Parts needed

Here is a list with the parts needed for cowl induction on a Firebird (either for repair of a stock system from 82-84 or retrofitting to a LG4, L69 or LO3 engine). Items with a * are mandatory:

• * Cowl induction hood (2 parts: hood plus scoop insert aka air inlet panel)
• * Honeycomb mesh grille
• Drip rail (optional)
• * “Airbox” with screw clip and screws
• * Solenoid with link arm (+1 screw to attach to flap)
• * Solenoid bracket and 2 screws
• * Air cleaner lid with hole
• Lid spacer
• * Silicone gasket +2 retaining clips
• Hood side harness
• Socket for harness
• * Vacuum switch
• * Socket for vac switch
• * approx 2 yrds of vac line
• * Vac line T piece
• Temperature switch
• adapter for temp switch (if needed)
• * Standard automotive relay SPST
• * Some 14 gauge wire and electric sockets

Cehbra

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Cowl induction hood (GM #10014649)
By far most of the power bulge hoods were made of steel, although a few ones out there are made of aluminum. These aluminum hoods are considered the holy grail of thirdgen Firebirds and go for $$$. Steel and aluminum power bulge hoods both share the same GM part number, but some aluminum hoods have an additional A stamped on the underside. Of course a steel hood will do for the project



Air inlet panel (GM #10035292)
Pontiac called this insert “ornament”. Made of steel (edited: made of zinc) it is the frame for the opening and holds the grill. It was water sealed to the hood with a foam gasket (GM #10030132 AIR INLET PANEL GASKET). I instead just used some adhesive window seal rubber.

Cehbra

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Air cleaner intake (GM #10026078)
I call this part “airbox”. It is made of plastic and is the main hood side element that ducts cold air from above the hood into the air cleaner. The LU5 crossfire version has the GM #10026515.



Solenoid (GM #10025693)
The rod of the solenoid extends outward by 18 mm (0.7 inch) when activated. A spring pulls it back when there is no current. The solenoid itself is a rather delicate device as it tends to burn out when operated for a long time. So it might not be suited for manual operation (e.g. through a switch) but should only be activated during wide open throttle when a lot of air is needed.

Cehbra

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Air cleaner (GM #25043302)
The air cleaner base that was used in the 82-87 LG4 and 84-86 L69 engines is the same as in the later 88-92 LO3 engine. And it’s also placed in the exact same spot. With the functional cowl induction setup the lid was different though: there is an opening at the top, which is encased by a seal/silicone gasket. The lid is made of two parts actually. The inner smaller lid is to seal the round air filter top, so that there is no dirty airflow directly from the hole to the carb.



Seal (GM #10026013)
That silicone gasket seals the space between the air cleaner lid and the air box. It is held in place by two retainer clips and mounts in the hole from the air cleaner lid.



Scoop grill (GM #10023479)
Also called Hood Air Vent. The screen insert serves the purpose of filtering the air from large debris like leaves or insects. The grill is made from aluminum die cut in a honeycomb style. Originally it was anodized in black, however many of the grills I have seen have faded to silver. It was discontinued at the end of the 1984 production year. When the Firebird Formula was reintroduced in 1987 the power bulge hood was sealed off and the scoop grill was replaced with a <strike>plastic</strike> (edited: aluminum) block off plate (GM #10024254). Interestingly some first owners claimed that their 1982 Trans Am came with both inserts. The honeycomb grill was on the car and the solid one was in a GM envelope.

Cehbra

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Drip rail (GM #10028254)
The drip rail - or „underhood water deflector“ as called by Pontiac - actually was not introduced until 1983. According to the Pontiac workshop manual some 1982 and early production 1983 Firebird models with hood scoop did experience spontaneous pulse wiper operation due to water entry into the pulse wiper motor module. This condition usually occurred when the vehicle was run through a car wash. The deflector was added in production to 1983 vehicles approximately mid-March of 1983 and was discontinued at the end of 1984 when the cowl induction hood made its demise.
It was accompanied by a rubber shield (GM #20427916), that was mounted into the 3 cowl lip clips. I have actually never seen that shield anywhere. To install the drip rail the two lateral scoop to ornament screws had to be removed and the deflector tabs were inserted between scoop and ornament tabs with the deflector opening towards the left side of the vehicle.



Looks like new after washing, sanding and a coat of black plastic paint...


Cold override switch (GM #25036589)
This is a device manufactured by OEM supplier ACDelco, original part# D1871 also referenced as SWITCH ASM A/CL AIR INT SC. It is a temperature controlled switch (on/off) which is normally open (NO) and closes at a temperature of 140°F (60°C). It was mounted in the back of the cylinder head on the driver’s side.

Cehbra

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Vacuum switch (GM #10032130)
The original ACDelco vacuum switch is normally closed (NC). It was referenced as SWITCH, AIR INT SCOOP DR A/CL. It must be connected to a vac line from the carburetor. Unfortunately the original switch is almost unobtainable. The one I eventually got, needed extensive refurbishing. But fortunately there is the ACDelco 212-331 ported vacuum switch, which looks exactly the same and can be ordered new in many places. The only downside: it’s a normally open (NO) switch. If we are to use that one, we will need to add a relay, see later.




Harness (GM #12101865)
Wire with connectors from solenoid to GND and to vac switch.

Cehbra

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There's more in the line. Part 4 coming soon, hang on. Need to get some stuff done first.

Agent13

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Excellent writeup. This explains why I couldn't find a vacuum switch on my new LU5 car....

Cehbra

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Yep, no vac switch on LU5

On to the last part...

Cehbra

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Part 4: Fitting cowl induction to LG4/L69/LO3

Of course not all the OEM parts are needed to get this working. You can probably just omit the drip rail. Furthermore the solenoid can be hardwired to the vac switch or linked with a custom connector. You could also skip the temp switch, as this is probably not a key element.

I tried to stay as close to the original wiring diagram as possible. Here is how I ended up wiring my stuff:

My TBI Firebird was not equipped with an oil pressure on/off switch, but rather with an oil pressure sensor, which changes resistance depending on pressure. So how to sense if the engine is running? There are several ways to solve that problem. One would be to fabricate a Y piece to add a pressure switch – probably not a good idea as leaking would be almost inevitable. Another possibility could be to use the D+ line from the alternator to drive a relay - IF your alternator has a D+ terminal for an indicator light (mine has not). I chose to use the fuel pump relay in the end, which gives 12 V when the fuel pump is active. I’m sure there are more ways to do it… anyone got ideas?

Naturally, instead of doing all that, you could also use one of the pink/black wires directly. Those are hot in run/bulb test or start. Though you should be aware of the fact, that in this situation the solenoid is active, when the key is in run with the engine off.

Cehbra

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Originally the temperature switch was located at the back of the cylinder head on the driver’s side. I had it installed by a professional who used an adapter, as the bolt thread on the engine was too big for the temp switch.



Just one wire connected in this pic...

Cehbra

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As I mentioned, there is the ACDelco 212-331 ported vacuum switch, which unfortunately is a normally open (NO) switch. This isn’t a real problem though, since we can make it work like the original switch if we drive a relay coil with it in this way:

Cehbra

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Teeing from the carb vac line is simple, as you will only need a proper T piece and some standard vacuum line.



In the early thirdgens the vac switch was mounted by the firewall on the driver’s side. Just use an existing hole or drill one on one of the brackets that are mounted already. In some early thirdgens the vac line came from a vac box also located by the firewall.

Cehbra

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To attach the open type lid to a late thirdgen air cleaner you will need a little spacer as the screw thread in the newer cars is a little too short. I made one from steel in a cone shape with a height of 10 mm. This is not needed on the original LG4/L69 engine. Apart from that the lid is a simple drop in.

Be aware that the lid itself consists of two pieces: the lid itself and an inner dish. Sometimes the smaller inner dish is missing. That’s a bad thing, as unfiltered air will go to the carb that way.



To correctly align the lid opening with the air box opening the lid must be rotated until the air cleaner snorkel lies right where the letters “SNKL” (for snorkel) are stamped on the edge. The snorkel should then be between the two bumps to the right and left.

Cehbra

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For the hood side elements first mount the honeycomb screen, and then add the airbox. If you have one, the drip rail will be the last to mount and fix with appropriate screws.

Cehbra

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Fail testing the setup
Just revving the engine is not going to activate the solenoid. The engine must be under load i.e. accelerating. But there is a very easy method, which is also described in the 1984 Firebird manual: when the engine is running (oil pressure switch closed) AND the engine is warm (cold override switch closed) then plug off the vacuum line from the vacuum switch. The vac switch closes and current flows to the solenoid, which then should move. If it does, the system is working.

The solenoid makes a lot of noise when activated. With the hood open and me standing next to it it’s really an annoying knock like someone poked the hood with a hammer. Strangely that sound cannot be heard inside the car when the car is moving. I’m actually thinking of adding an LED to the cowl grill that lights up under WOT to know when the system is open when I’m on the road.

Cehbra

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Results
When I took the car for a test drive after adding cowl induction I was rather underwhelmed. At first I didn’t notice any increase in power or responsiveness. The light bulb moment only came when I had to temporarily remove the open air cleaner lid to restore it from some rusting and I replaced it with the orirginal closed lid. The car suddenly became sluggish and wouldn’t accelerate the way it did before. So in the end I can say that there is a definite increase in torque, which is noticeable – not much, but for me it was worth the effort. Anyway, I woudn’t like to have that nice hood on the car not do anything!

Cehbra

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So that’s it!

I hope you enjoyed the little excursion into Pontiac history. Thanks for reading and commenting.

*flies away*

fteufert

Great write up!

Two things:

First, I do not recommend keeping the solenoid powered for long period of times. I have seen cars wired to open the flap when the car is started, and that will cause the solenoid to fail prematurely. It is designed to only work for short periods of time. I personally disconnected the solenoid and wired the flap open.

Second, does anyone know where a replacement seal PN 10026013?

((Mike))

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Thanks a million for that writeup! I really enjoyed the read. It was nice to learn something new. I have always been a camaro fanatic and never took the time to learn about the firebirds. I appreciate the time you took to do this!

((Mike))

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Its too bad the Camaro didn't keep the hood flaps from the crossfire hood to use on the L69 and LG4 motors like the firebird did. Its really a neat set up!

PurelyPMD

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That would have been nice!

Great write-up - thanks for all the info!

Cehbra

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Totally! This is why Pontiac put so much effort in the setup.
Have you had your flap open for a long time already? No problems with that? Just because I read about some people who said that keeping the flap open all the time caused too much water to get in the engine
and eventually a hydrolock was the result. If constantly keeping the flap open works, then all that wiring wouldn't be necessary.

The seal shows up on ebay now and then. Personally I haven't ever seen a NOS one. I could check tonight if I have a spare one in the basement.

fteufert

I have never had issues with water entering the engine. I do have the drip tray installed.

dmccain

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My flaps had a switch wired to it to open them. If I left it open long I noticed the solenoid would get pretty warm. When I took the air induction off my car I left my hood scoop open. It does have a plate there just open slots. Surprisingly with the exception of one terrible lightning storm I got in on the way back from a show once I have had no trouble with water getting under the hood of my car at all. Im sure the open scoop adds some air under the hood I can actually hear it pretty good when I mash the gas.

SolarGoldRaptor

Thank you so much ! I have to test the set up on mine, I could only guess how it was all plugged as it was missing on my car and I had to find a good unit. I hear the solenoid work once when I was working on the engine running, scared the hell out of me, but I can't tell if I did something or if it worked by itself as it should.

I was thinking about adding an adhesive 12V red led strip behind the flap so it shows when it's open. That could look pretty cool at night.

Cehbra

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Thanks for all the comments guys! I'm glad you appreciate it. That way I know the work was good for something...

Cehbra

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That is a cool idea! Much better than a single LED. I might try this, too. Post up if you do it!

okfoz

Thank you for the write-up, very informative.

I put the setup on my 87 LG4 for a while (before going to TPI) and I noticed a small difference, it did breathe a bit easier. If you ever get a chance, take a piece of tape, and some tissue paper to the top of the cowl. You will see the paper get sucked to the little grille as you go faster...

My solenoid was shot, so I did something to the arm, I forget if I flipped it over or what, but it was open all the time.

I never had a problem with water getting into the intake, or hydro-lock, but again it was only on there from 2000-2002, and I didn't go driving in the rain unless it started after I left...

I pulled a hood off of an early Trans Am and it had BOTH the grille and the solid piece on it. It appeared to be factory, no envelope.

Also the piece on the hood was originally a zinc die-cast, my 87 has a die-cast piece from the factory, but you are correct and the later cars (91& 92 for sure) were plastic, I am not sure when they went that way. I want to think my 89 has a die-cast as well, but I would have to check...

John

Cehbra

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You mean the insert that was called "ornament"? You could be right. I thought it was steel actually - not plastic. But it feels like aluminum to the touch but is heavier. you're probably right about it being zinc.

okfoz

Yes, for some reason they call it an "Ornament" I guess it is a good of description as any... It is definitely not Steel, take a magnet to it. Pretty sure it is a Zinc, they used to make a ton of small parts out of zinc because it was easily cast. Our mirrors are Zinc for example, Some older car grilles were Zinc, until they went to plastic. Door handles were Zinc (inside and outside)...

I know my 87 is not plastic...

John

SolarGoldRaptor

Yes, mine isn't original to the car (that was missing too), but it's potmetal. I broke a stud when tightening it. Do NOT put paint on the studs.

edpontiac91

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I picked up one of these open screens and it was plastic. I just used a semi-flat black spray paint and it looks perfect. If for no other reason, it looks good being a little high tech on my 1991 Formula, and I guess it does help in removing heat from the engine when driving because if you put your hand over it in cold weather, even at idle, you can feel the heat coming out.