1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

mech secondarys

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Old Oct 6, 2004 | 03:45 PM
  #1  
Dannny's Avatar
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mech secondarys

are the secondary barrels meant to be opening at the same time as the primarys?

i tried modding them and now they both open at the same time and hit WOT at the same time too, low end drivablity is really bad, pretty much the only way i can drive the car is with the choke until 3000, then gun it
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Old Oct 6, 2004 | 03:52 PM
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Check out the FAQ at the top of this section. It should help you out better than I could. I won't be getting to this mod until next year.
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Old Oct 6, 2004 | 03:57 PM
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I have my mech secondaries so they open at about half a throttle.
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Old Oct 6, 2004 | 04:04 PM
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mine's about a quarter of the way down when i hit the gas... they still open all the way, so i have no complaints. i don't bog it much anyway... i can control my foot...
P.S. Bass, this is the easiest mod I have done to my car just to let you know... it was so easy I had my mom help me and control the throttle while i tied the linkage.
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Old Oct 6, 2004 | 04:21 PM
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hmm... maybe i should post my setup... involves a paperclip... and that's it.
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Old Oct 6, 2004 | 04:37 PM
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god dude, you must get the worst gas mileage ever!
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Old Oct 6, 2004 | 07:56 PM
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by the way no they are not supposed to open at the same time until you are about 1/4 1/3 or 1/2 throttle. (somewhere in that range). Like bass said check out the faq. And by the way bass i rebuilt my carb and while I had it out converted to mechs in like 10 min while watching the simpsons...easy.
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Old Oct 7, 2004 | 12:03 AM
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post that link please i wanna see it, got a mean streetport on a 12a and that extra air means more power
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Old Oct 7, 2004 | 12:18 AM
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I think mine are about half too. I know i have a lot of room of just primaries -i barely ever use the secondaries daily driving, unless im in the mood for some fun
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Old Oct 7, 2004 | 08:02 AM
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From: Trying to convince some clown not to put a Holley 600 on his 12a.
The linkage dictates when the secondaries begin to open.
When converting to mec.sec.s, all you're doing is disconnecting the vacuum operation box linkage, and locking in the actuation linkage . You have to have someone depress the pedal fully and tweak linkage a bit so that both sets of butterfly vlaves are perfectly vertical.

There's a post in the archives on how to do this properly, including how to modify your accelerator pump to deliver a larger shot of fuel for a longer duration so that as you depress the pedal fully, you still get a shot of fuel.

You still can expect nothing if you stomp the pedal @ anything under 4200 RPM.
It's mechanical secondaries, not nitrous.
But if you use a little finess on the pedal, you will learn just by feel and sound when you can crack open those secondaries and fly.
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Old Oct 7, 2004 | 12:13 PM
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yeah it is mech secondaries and not nitrous, but after 4k rpm, when one stomps on the pedal, it does feel like a small shot of nitrous

I use them in my daily driving, er, daily. I get 12 mpg
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Old Oct 7, 2004 | 03:07 PM
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could someone post a pic of their mech secondaries...im a bit carb retarted...and am not sure where the linkage is or anything like that. thanks
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Old Oct 7, 2004 | 03:57 PM
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Originally Posted by cdrad51
yeah it is mech secondaries and not nitrous, but after 4k rpm, when one stomps on the pedal, it does feel like a small shot of nitrous

I use them in my daily driving, er, daily. I get 12 mpg
I use them like once everyday or so. i get 12.7 mpg
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Old Oct 7, 2004 | 04:28 PM
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Wow. How do you manage that? I use them everyday like, 10 times a day, and have 150s and 175s for fuel jets, and still get only 0.7 mpg less than you? Unless I'm getting less than 12 mpg, which is only a guestimate.
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Old Oct 7, 2004 | 04:36 PM
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well i know for sure that i get 12.7. i did the fill the tank, use gas, fill it back up, and calculate- procedure. What rpms do you shift/drive at?

Im gonna start using my secondaries more and not care so much about gas mileage. I need to have more fun
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Old Oct 7, 2004 | 05:09 PM
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Well, on my daily routine of driving to work, at the beginning of my runs I usually cruise at 3-3.5k and shift at about 4k rpm. By then I'm on the on-ramp, and when that light goes green I take off at about 3k rpm, and redline it in the first 3 gears. Then I cruise at 4k rpm so that I'm ready if I need to punch it. If I'm over 5k rpm and there is no need (i.e. no space) to punch it, I'll shift at that point. on the last stretch of highway I cruise at 5k rpm on 5th ( ). Total is about 20 miles.

At the end of the day when I come back home is pretty much the same basic routine.
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Old Oct 7, 2004 | 11:40 PM
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sounds fun didnt you use to get 10mpg?
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Old Oct 8, 2004 | 12:10 AM
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Yes it is fun

I had an earlier modded Nikki carb with a bored out 25 mm primari venturi, 160s for primaries and 190s for secondaries. Back then I was getting 10 mpg , but it was running too rich and didn't perform nearly as good as the Sterling carb.
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Old Oct 8, 2004 | 09:21 AM
  #19  
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From: Trying to convince some clown not to put a Holley 600 on his 12a.
You guys really need to play around and take advantage of the modified emulsion systems in your carbs. I can't stress that enough. I really REALLY can't!

By utilizing that aspect of tuning, you can get the same MPG @ 3600 cruise as 5500 cruise.
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Old Oct 8, 2004 | 09:26 AM
  #20  
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I suck at tuning/doing stuff with carbs thats why i paid you to send me that fine piece of work I kinda scared of it. lol
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Old Oct 8, 2004 | 09:32 AM
  #21  
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I am gonna read more, research more, learn more.- i need to.

Now im having issues with my clutch though
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Old Oct 8, 2004 | 07:20 PM
  #22  
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Hey Cdrad51 you treat that green light as a pro tree and the onramp as a dragstrip that is so cool I do the same thing. I want mechanical secondaries to but I am going to get a sterling carb with it.
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Old Oct 8, 2004 | 08:41 PM
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lol I guess so, never thought about it that way

Usually by the end of the ramp and as I'm entering the highway itself I'm going slightly faster than the highway traffic already muahahaa
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Old Oct 8, 2004 | 08:49 PM
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how bout show some pic, or post link to the guide to link it up
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Old Oct 8, 2004 | 09:51 PM
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I think there's something in the FAQ section about it
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