Cowl Flap

[75SHRK]

Hello, Just another new member on board.I have read your forums for sometime now.I have gained alot of good tips while i have been restoring my 75 coupe.My question is when does the hood cowl flap operate.Had hood off and flap out and it operated when wired to a battery but does not open when ignition on . Cannot find anything in repair books.

 

[Vettehead Mikey]

This was covered in a similar post a week or two ago. There's a switch under the gas pedal that triggers the flap open at WOT.

 

[Tom73]

Take a look here for how it works. This is for the '73 but they are the same.

tom...

 

[wishuwerehere82]

I just curious. If you removed the flapper, would it affect anything except the warmup time and emmisions? Seems like cooler air all the time would give better performance.
I took mine off for a while, and liked the results, but put it back on fo inspection time.
Pete.

 

[Bill75]

Hood Scoop

I was just working on mine last night. Mine isn't working properly because the switch on the gas pedal is not being tripped. Between the floor insulation and carpet thickness there isn't enough travel left. Looks like a little surgery is in order on the carpet insulation.
In case you have trouble you might also look and see if you have the same issue that I do.

Bill

 

[Vettehead Mikey]

I just curious. If you removed the flapper, would it affect anything except the warmup time and emmisions? Seems like cooler air all the time would give better performance.
I took mine off for a while, and liked the results, but put it back on fo inspection time.
Pete.

The flap has no effect on warm up time or emissions. The air cleaner is an semi open type that draws air directly from the engine compartment and/or the ductwork leading to the flap.
I've always thought that the whole thing was a little 'gimmicky' anyway and the weight, cost and complexity would negate any supposed performance gain. Possibly if the ductwork/flap could select cold air ONLY instead of a mix of the two PLUS the car was going fast enough to actually build pressure in the ductwork, it might be worthwhile.

 

[wishuwerehere82]

Good luck with your flapper switch, my computer controls mine. I'l be damned if I can tell that it actually moves it.
There's now way to tell other than put a video camera under the hood while I'm moving.

Pete.

 

[wishuwerehere82]

The flap has no effect on warm up time or emissions. The air cleaner is an semi open type that draws air directly from the engine compartment and/or the ductwork leading to the flap.
I've always thought that the whole thing was a little 'gimmicky' anyway and the weight, cost and complexity would negate any supposed performance gain. Possibly if the ductwork/flap could select cold air ONLY instead of a mix of the two PLUS the car was going fast enough to actually build pressure in the ductwork, it might be worthwhile.

I thought it ran better without it. It could be a problem in a rainstorm though, I think. Since it is wide open to the outside, it may suck a lot of raindrops into the intake.
I always heard a lot of benefits from water injection anyway, if only in theory.:L

Pete

 

[wishuwerehere82]

I was just working on mine last night. Mine isn't working properly because the switch on the gas pedal is not being tripped. Between the floor insulation and carpet thickness there isn't enough travel left. Looks like a little surgery is in order on the carpet insulation.
In case you have trouble you might also look and see if you have the same issue that I do.

Bill

Bill,
I just removed mine a minute ago. Let's see if there's any improvement.

Pete.

 

[75SHRK]

Thanks for the info I will check it out tomorrow after the grass is cut.One idea I had was to have my wife shine a flashlight from the inside and press the gas pedal WAO.

 

[Tom73]

I just curious. If you removed the flapper, would it affect anything except the warmup time and emmisions?

The big issue here is more of a noise issue than anything. The db's go sky high when that thing is open.

Mine isn't working properly because the switch on the gas pedal is not being tripped. Between the floor insulation and carpet thickness there isn't enough travel left. Looks like a little surgery is in order on the carpet insulation.

Had the same problem with mine and cured it by putting a piece of rubber hose (vac tube) over the arm of the switch, thus making the arm thick enough for the gas pedal rod to trip it.

Thanks for the info I will check it out tomorrow after the grass is cut.One idea I had was to have my wife shine a flashlight from the inside and press the gas pedal WAO.

When you push the gas pedal, with key on but engine not running, to WOT you should hear the selionid click to open the flap.

 

[Bill75]

Hey Tom.......Great idea on the tubing. I'm going to try it out!!!!!!!!

I'm probably also loosing a little on WOT at the carb too.

Thanks

 

[Robin7TFour]

hello all, the tubing is a great idea if you have a manual tranny. i think the kick-down is wired in the same switch on the TH400's. at least that's what i recall.
then again it doesn't matter. the painter promises me my hi-rise hood next week! i've been waiting so long,but i can't fault tim(painter). his dad went into the VA hosp last month and never came out. i felt really bad for him

Robin

 

[CQRT]

Greetings from AZ:
In the "for what it's worth" department, I've removed the solenoid and cowl door on each of my 4 c-3's while in Ohio and here over the years under the potentially misguided belief that "more air" was better (and I LOVE the sound when you ROMP it)
No downside on any of the cars although they were never driven in rain or extreme cold.
Regards-
CQRT in AZ