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Secondaries not working on Edelbrock 1407
#1
Hey guys,

Having trouble that the secondaries don't appear to be opening / working right on this carb. Everything seems to move freely and stepping on the gas with the engine off the secondary opens and the air driven butterfly above that seems to move freely by hand. When driving the car you never hear that sound of the secondaries opening and the car seems low on power. 

The engine is a 351C 4V with a Torker II manifold. Since everything is moving freely my thoughts were that free flowing manifold was making for lower air movement and the air driven butterfly just isn't getting enough air past it to open all the way. That's totally a guess though. This was on the car when I got it and don't know if it ever worked right. 

Appreciate any advice in debugging this. 

Thanks
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#2
Do you have a copy of the owner's manual?
https://www.edelbrock.com/edelbrock-tech...rce-center

The Torker II will flow more air, not less. What kind of air cleaner do you have? Will it handle the air flow needed by a 750 cfm carburetor? Dirty filter?

Does your engine need a tune-up? The engine has to be running right to pull in a lot of air. Is the timing set right? What condition are the spark plugs?



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
Hey Don, thanks for the reply. 

My thinking was probably off on this, but my assumption here was that open manifold is less restrictive so at lower RPMs there will be less velocity. It all goes through the carb, so that is probably not the right way to think about this, but just trying to make sense on why it wouldn't open. 

Running a new 14" K&N filter and have tried it with no filter around the block to see how it would do. New plugs, wires, cap and rotor. As far as timing, I currently running at 15° BTDC. That said I really don't know where I need to be with this setup. I did get a vacuum gauge, but haven't used that to help time yet and not really sure how to do that, but reading up on that now. 

Thanks
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#4
If everything else is good, there's no reason the secondaries aren't opening. I guess you'll have to tape your cell phone to the underside of your hood and get a video of it to see if it is opening. Smile

It will not open at lower RPMs under any circumstances. Depending on various factors it'll probably need 3 to 4,000 RPM before they open.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#5
Dude, check and adjust the secondary air valve wrap. it may have to be set looser than edelbrocks 1-1/2 turn setting.                                                                                                          Boilermaster
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#6
After a lot of tinkering the last couple of days I was able to get more power out of it. I don't necessarily hear the secondaries open or feel the surge like I'd expect, but it's enough to break the tires loose a bit if I just stomp on it in 2nd gear. Advanced it using the vacuum and listening to it just to see how that worked. I'll keep tinkering with it from there.

I feel like this carb is just not setup right for the car. Harder to start than it should be, stumbles off the line, not enough power all around etc. Ignition looks good with everything replaced, plugs wires, coil etc. I think I probably need to get the Edelbrock tune kit for the carb so I can try different springs and metering rods. If I could figure out how to pay for it, I'd fuel inject it and be done with all that.

Thanks for the help. I think I have a bunch more work to do to get this thing running right.
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#7
The purpose of the air valve is to gradually open the secondary circuit, regardless of how far open the secondary (mechanical) throttle blades are, to prevent bogging from being too lean when the secondary system opens. That is why I asked you if you had the Edelbrock manual, so you could read up on how it operates. It does not operate like a Holley double pumper. If you want to mechanically control the opening of the secondaries block open the air valve and you will be able to hear and feel the effect and understand why the air valve is there. The air valve does not begin to open until there is enough air flow through the carburetor and then gradually opens as the engine speed increases and the air flow increases. The way it operates is more like a Holley vacuum secondary carburetor, you really don't any surge as it opens.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#8
Have you adjusted the air valve flap?
https://www.bing.com/videos/search?q=wir...54&PC=MOZA



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#9
Thanks Don, I actually do know how they are supposed to work and was of course assuming that I should get surge of power or something when they open. Never used this so not really sure and just basing this on old experiences with other cars as I'm returning to this stuff after probably a 30 year break. I'd also been assuming that this carb was setup for this car before I got it, but I suspect it was 2nd hand and never was right for it or other things like the cam and rockers were changed and the carb was never adjusted for that.

I do have the manual and have looked that video and other info but so far everything I've seen is about adjusting Edelbrock Thunder series and not the Performer series. That air valve is substantially different from from what I can see.

While I am going to keep working at this, there is a guy in town here that has a bunch of new Fitech 600HP EFI systems that he is selling at a good price. It's still more than I can spend right now, but it is tempting to try and cut to the chase and go EFI. Heck, might make sense to try and do some kind of group buy to get better pricing if others are interested.
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#10
I don't blame you for wanting a FiTech, it's on my wish list, too, tired of rebuilding and tweaking on carburetors.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
[+] 1 user Likes Don C's post
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