70 Chevelle Cowl Induction Hood - Page 2 - Chevelle Tech
Troubleshooting Diagnosing problems done here.

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post #16 of 25 (permalink) Old Aug 24th, 15, 8:02 PM
Chainsaw936
 
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Re: 70 Chevelle Cowl Induction Hood

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Originally Posted by jjr158 View Post
The video appears to be an automatic Chevelle. When the Chevelle enters the freeway ramp I see that the flapper door does open. However, it appears as though the flapper door opens at approximately 3000 rpm's give or take a few rpm's and not passing any cars suggesting that the throttle was not WOT. My flapper door only opens in forth gear at or near WOT. I have a few more things to check before I throw in the towel.
I put the smaller vacuum line on this weekend with almost no change. If anything it's even less responsive in 4th than before. I've checked everything except the pod diaphragm but with suction on the hose, it closed and stayed there until i removed my finger. Last thing is shimming the outer flapper to get it level. Has anyone used the shim kit from opgi? I'm assuming that is what the kit is for.

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post #17 of 25 (permalink) Old Aug 25th, 15, 8:00 AM
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Re: 70 Chevelle Cowl Induction Hood

JJR that's from my 70 Monte that has a Chevelle cowl induction hood on it. During that video we were only running 65mph right around 1900 RPM's. The part where the door opens was due to a timing issue. I've never been in a 4 speed Chevelle only in a turbo 400 and when getting on the throttle the outside door would open.
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post #18 of 25 (permalink) Old Aug 25th, 15, 8:44 PM Thread Starter
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Re: 70 Chevelle Cowl Induction Hood

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Originally Posted by monte7ocar View Post
JJR that's from my 70 Monte that has a Chevelle cowl induction hood on it. During that video we were only running 65mph right around 1900 RPM's. The part where the door opens was due to a timing issue. I've never been in a 4 speed Chevelle only in a turbo 400 and when getting on the throttle the outside door would open.
Thanks for the information. With my Chevelle It only opens in 4th gear and I have to have the accelerator to the floor at WOT to get the flapper door to open.
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post #19 of 25 (permalink) Old Aug 26th, 15, 11:40 PM
Chainsaw936
 
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Re: 70 Chevelle Cowl Induction Hood

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Originally Posted by mr 4 speed View Post
Make sure you have full throttle actuation, meaning when the gas pedal is to the floor it also fully open at the carb.
In my quest to get the cowl working, I checked the primaries on carb per mr 4 speeds suggestion. Warmed up motor to 180 to make sure the choke was not causing them to stay closed under WOT. Had the wife press the gas all the way to the floor and nothing? Primaries didn't move. The car has felt slow for a BBC and i'm guessing this is a big reason. They aren't hanging up and move pretty easy when I manually move the butterflies. I'm a noob and don't have the experience on how to fix it so it's going in for a tuneup. Let you know if this has an effect on the cowl flapper working better.
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post #20 of 25 (permalink) Old Sep 23rd, 15, 6:11 PM
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Re: 70 Chevelle Cowl Induction Hood

Quote:
Originally Posted by chainsaw936 View Post
In my quest to get the cowl working, I checked the primaries on carb per mr 4 speeds suggestion. Warmed up motor to 180 to make sure the choke was not causing them to stay closed under WOT. Had the wife press the gas all the way to the floor and nothing? Primaries didn't move. The car has felt slow for a BBC and i'm guessing this is a big reason. They aren't hanging up and move pretty easy when I manually move the butterflies. I'm a noob and don't have the experience on how to fix it so it's going in for a tuneup. Let you know if this has an effect on the cowl flapper working better.
and.....................

Marc S


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post #21 of 25 (permalink) Old Sep 23rd, 15, 7:27 PM
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Re: 70 Chevelle Cowl Induction Hood

LACK of vacuum is what makes them open. When the car is off the flapper is open, with it on itís closed. Itís working, just not as quickly as you want.

I find it incredibly hard to believe your wife floored the car and it the primaries did nothing. Iím almost certain you are not looking at the correct part(s). That being said, even running crappy will have extremely little effect on the flapper. Higher RPMís has nothing to do with it either, LOAD does. At a standstill (as you said) there is NO load. Replace the pod and remove the stupid slow control valve and be happy.

Mine with a 4-speed

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Last edited by 70 nialator; Sep 23rd, 15 at 7:48 PM.
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post #22 of 25 (permalink) Old Sep 23rd, 15, 7:45 PM
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Re: 70 Chevelle Cowl Induction Hood

Same car, same day... LOOK CLOSE. All the RPM and power in the world and as SOON as the tires break loose IT CLOSES Because the load is gone.


If you donít push the limits how are you going to find the weak spots?
USMC- Retired
My car: 1970 Chevelle

Factory 12 bolt /4-Speed Malibu -Dual stage wet nitrous with heater & purge - Holley Strip Dominator, Speed Demon 750 CFM - (All MSD distributor, blaster 3 coil, 6AL, & 3 stage retard) - 4 wheel disk brakes - Aeromotive Fuel system Ė Boss 338 18ís - BMW 5.25 true HID projector mod - and of course... the FLAPPER - bla, bla, bla.. lots of other expensive stuff I canít remember
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post #23 of 25 (permalink) Old Sep 24th, 15, 12:32 PM
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Re: 70 Chevelle Cowl Induction Hood

Quote:
Originally Posted by chainsaw936 View Post
In my quest to get the cowl working, I checked the primaries on carb per mr 4 speeds suggestion. Warmed up motor to 180 to make sure the choke was not causing them to stay closed under WOT. Had the wife press the gas all the way to the floor and nothing? Primaries didn't move. The car has felt slow for a BBC and i'm guessing this is a big reason. They aren't hanging up and move pretty easy when I manually move the butterflies. I'm a noob and don't have the experience on how to fix it so it's going in for a tuneup. Let you know if this has an effect on the cowl flapper working better.
you need to loosen the nut that holds the throttle bracket on the carb and gently push the bracket towards the firewall.


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post #24 of 25 (permalink) Old Sep 24th, 15, 8:34 PM
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Re: 70 Chevelle Cowl Induction Hood

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Originally Posted by 70 nialator View Post
Same car, same day... LOOK CLOSE. All the RPM and power in the world and as SOON as the tires break loose IT CLOSES Because the load is gone.

http://www.youtube.com/watch?v=SWcb1ZtgjeQ
It still shouldn't close! Mine has never closed because of loss of traction.

*Full disclosure I do not run the little plastic vacuum control valve in line with the canister so maybe that has something to do with it.
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post #25 of 25 (permalink) Old Sep 24th, 15, 9:12 PM
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Re: 70 Chevelle Cowl Induction Hood

I'll have to shoot vid of my 70 Elky
the few times it has idled far down it wobbles....stall warning!
I have automatic, at WOT, it opens and stays open

George Kettler
o SOLD 8/2016 my beloved 1970 Elky 496.
o 68 Vette 427/M-20/3.36 28 year owner

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