'82 Functional Scoop - W/O Crossfire System - Third Generation F-Body Message Boards

kboehringer · 05-17-2006, 11:17 PM

TGO Guys,

I've been rackin' by brains trying to figure out a way to make the functional scoop of my son's '82 Z-28 work without the original CrossFire. The solenoid works and the doors can be made to function with battery voltage. The original crossfire (and the entire crossfire engine wiring harness & computer are gone). The current wiring harness and computer are from an '86 LG4. The car is completely computer controlled with a Rochester E4ME and and all the appropriate pollution connections installed and functional (i.e. TPS, MCS, O2 Sensor, MAP, Baro, Knock, Etc.)

I thought there might be some way to "PIGGY-BACK" the signal from the TPS (Throttle Position Sensor) and convert that to higher voltage(s) to make the Hood Doors functional. That would allow partial to full opening as voltage from the TPS increased upward from .48v at idle? I have absolutely no idea how the original system functioned, although I assume there was an Output signal from the ECM that provided voltage/signal to the Solenoid.

I know it may seem a little stupid but my son thinks this would be really really cool and I want to make it work for him. I kinda agree it would be pretty cool even though it won't really be doing anything but letting water into the engine compartment

Anybody made this work? Any ideas? Is there any signal from the '86 ECM that could be used to operate the Scoops. My basic electrical ability is sound, but I have little advanced abilities...

Thanks a bunch in advance....
Kurt

EDIT: Spelling

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mrbunker · 05-18-2006, 10:10 AM

I have an 82 with crossfire. The signal comes from the ECM to open the doors at WOT (wide open throttle). I don't believe piggy backing the TPS will work unless you could find some type of relay that would operate when you reach a specific voltage. You could place a microswitch in a location that would operate when you hit WOT.

TheWesman · 05-18-2006, 10:34 AM

I've thought about doing the same if I can ever find a crossfire hood. I would like to fab up a slick looking custom/factory looking air cleaner to actually make it functional. Sort of like the old school ram air scoops.

I see 2 probable solutions.

1) Mount a switch to at the throttle pedal, like the kind used on say a nitro switch, clutch pedal or brake. Then adjust to suit.

2) Mount up a micro switch using a piece of custom bent sheet metal near the carb linkage that kicks on at WOT. Link sort of like a few nitro setups I've seen. I would also install a second arm/disarm switch in series, and mount it in the cab to turn it off on rainy days.

Depending on the amount current your switch can handle you may or may not have to use a relay based on the current draw of the solenoid.

I wouldn't use an existing throttle position sensor to do double duty by wiring it in parallel. Way more difficult in labor/parts/design to do it this way because a high impedence circuit will have to be build if you go that way.

TheWesman

kboehringer · 05-23-2006, 11:38 AM

TGO Guys,

Here's a new idea. Although not perfect it's better than nothing.
We are using a TH-700R4 Tranny (OD). Normally, we drive everywhere in OD. However, on ocassion we want a little better take-off and want to hold the 700 out of OD.

What wire is available that we can use to RELAY a signal to open the Scoops when the tranny is in "D". I know there are several wires at the Shifter Mechanism. Obviously, there is a neutral & park indicator and a reverse lights enable line. Is there anything in the shifter mechanism area that I could "Tap" to open the flaps when in "D"? could one of the wires (4?) that connects to the top of the T700 tranny be "Tapped"??

This wouldn't be the perfect set-up but I could easily wire up a relay if I have a source wire to closed a Normally open contactor.

OTHER INFO:
1986 LG4 Wiring Harness COMPLETE installed in this 1982 Z-28.

Any ideas......

Respectfully,
Kurt

coolram62 · 05-23-2006, 11:50 AM

Hello Kurt,
Wesman has probably the better idea.The TH400 used a micro switch to activate a solenoid for full throttle down shifts.The switch was located on the gas pedal assembly.Something similar to this or a NOS application would be better than trying to tax the TPS.
Mrbunker is correct the ECM controls the solenoid relay using the TPS as a reference.And this only happens when the car is at mormal operating temps and in closed loop.It's also interesting that the ECM doesn't allow the door solenoid to operate when the trans is in park.

kboehringer · 05-23-2006, 12:10 PM

Quote:

Originally Posted by coolram62

better than trying to tax the TPS.

Coolram,
Yea. I've kinda given up on the TPS idea. The Emissions and all the other factory stuff seems to be working perfectly. All I need to do is have a functional scoop and a lousy running carb/engine...........

However, I really don't want to add anything to the Throttle Linkage that could become lodged in the assembly or otherwise cause a failure (i.e. Jam in WOT

) Therefore, attaching something the Carb is not a option I want to pursue.

Thanks,
Kurt

Lo-tec · 05-23-2006, 12:31 PM

I did this using a factory GM vacuum switch. No vacuum=open flaps. The only downside is when you key the car on the flaps open up. A micro switch from a nitrous kit as TheWesman posted would work just as well, and not open them when keyed on. There is nothing for it to get wedged on, it would sit under the secondary linkage and only be triggered when the linkage arm rotated down on it (ran one of those on another car for different reasons). I wouldn't worry about them opening in the rain either, it shouldn't be floored then anyways.

phess11 · 05-23-2006, 01:07 PM

what air cleaner arrangement have you got to use the air from the hood? CFI air cleaner doesn't fit a carb very well, i wouldn't think.

kboehringer · 05-23-2006, 01:58 PM

Quote:

Originally Posted by phess11

what air cleaner arrangement have you got to use the air from the hood? CFI air cleaner doesn't fit a carb very well, i wouldn't think.

Phess11,
Currently....NONE. It's a looks kinda thing at the moment. However, we (my Son and I) want to grab a spare air cleaner cap from the J.yard and cut a oval opening in the rear (behind the filter) it will line-up very well with the backside of the CFI mechanism. We will add a drain to the base of the Air Cleaner assy to eliminate any water that enters.

Sincerely,
Kurt

coolram62 · 05-23-2006, 10:44 PM

Hello Kurt,
On the setup I'm speaking of for the TH400 the switch is mounted in the car above the gas pedal(I wish I had a digital camera I could take some pictures of the setup on my '73 CST).At WOT the gas pedal arm depresses the switch which activates the solenoid in the trans to downshift(B&M,Painless,Summit or JEGS probably carrys a prefab setup you could adapt).If you know someone that has a car or pickup with a factory TH400 look at how it's setup.You could do something similar using a switch to activate a relay to control the hood solenoid.The factory relay is the same as the relay for the fuel pump.
On the opening to mate with the hood were you thinking of something like the '70-'72 Buick GS used to mate the air cleaner to the hood?Only in reverse or would there be enough room?The second picture is the factory style kickdown switch.

kboehringer · 05-28-2006, 11:33 PM

TGO Guys,
I definately did not want anything in a location that could cause binding. I also needed a switch that was not a momentary contact (i.e. NOS Switches) and the switch had to be able to handle continuous 12volt for extended periods of time.

I found this OMRON switch at work, and although it's not exactly perfect, it works well. I milled a semi-attractive little "Shelf" for the switch and welded it to the A/C support bracket. The switch wheel is actually pointed the wrong direction (see photo) but I cut the wheel off another one and it had much more resistance. Power is provided by Accessory (only works w/key on) and there is a switch inside to disable the function in rainy weather. When the car reaches about 1500 rpm the flaps come open (100%). That's not exactly what I was after, but it works.

I purchased another Air Cleaner Top (retained the old one) and cut a couple slits in the rear with a zip-wheel. I tried to slightly MIMIC the look of the hood with a 1" piece in the middle. I retained the bends in the cap to maintain the rigidity and the 1" piece probably helps that also. The flap holes do NOT exactly line up with the air cleaner holes but air can get under the hood and be ingested through the air filter and into the carb when the flappers are open. [IMPO] Sucking engine compartment air into the carb is not the best choice. I don't feel this modification will allow much (if any) hot engine compartment gas to be ingested when the flappers are closed. I may add a "Seal" to the hood in the future. The carb should be getting quite good flow from the dual snorkel set-up as it is...... This set-up might be perfect for a single snorkel......

Tomorrow, (or whenever) i'll weld a small drain fitting into the bottom rear of the air cleaner and attach a small length of hose. To allow any water to be discarded down the rear of the engine over top the tranny.

It's not perfect and it may get a little refinement but this is my "Solution" to my son's request for funtional scoops.......

It does look pretty cool!

Any Thoughts?

Sincerely,
Kurt

coolram62 · 05-29-2006, 09:45 AM

Hello Kurt,
As i stated in your history thread this turned out great.Maybe fabricate an airbox attached to the air cleaner lid to mate with the air door assembly.The drain is a good idea as you will get water,as you probably already know,on top of the motor when it rain hard or even when you wash her.

Lo-tec · 05-29-2006, 03:52 PM