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

S5 T2 Weber blow through project

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Old Apr 23, 2008 | 12:06 PM
  #26  
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Originally Posted by slate84
thank you, thats what i'm running. have been planning on going about a setup like this but can't find the first thing on boost preping a dell.

Send it to Rob at the shack.


Ed
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Old Apr 23, 2008 | 01:35 PM
  #27  
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I've got another idea I'd like to play with, Jeff, maybe I can come over again tomorrow and try it.
Does it have to do with flipping the manifold?

I've gotta finish up the engine bay and get the exhaust in there so you can come over whenever.
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Old Apr 23, 2008 | 08:31 PM
  #28  
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You read my mind.

Looks like the studs on the manifold are offset slightly. It could still work if we slotted the holes on the turbo. Indeed, it seems to me like doing that and making an Aaron Cake style spacer would make everything fit really nicely with room for a heat shield or turbo blanket or something. I'll have to figure out which way could be done cheapest/easiest.
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Old Apr 24, 2008 | 12:51 AM
  #29  
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I still think doing it my way would work best and be cheapest.
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Old Sep 27, 2011 | 07:49 PM
  #30  
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sorry guys i hope im not making an idiot of my self but i have a similar project and i have no clue on how to boost prep a weber, any help will greatly be appreciated i want to run maybe 10 psi
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Old Sep 27, 2011 | 09:17 PM
  #31  
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As long as you know how a carb works, it's really straightforward and mostly the same as a normal rebuild. From memory, some things to watch out for:

The thin paper float bowl cover gasket that comes with most rebuild kits isn't good enough. I ended up cutting my own, but I think there are places that stock neoprene bowl cover gaskets. You'll most likely have to cut your own carb hat gasket, though.

If you have the carb spacers with the o-rings, I don't know whether they'll withstand boost. I have mine hard-mounted and haven't had an issue with it.

If your carb has the brass floats, you need to get some solid ones from a later style Weber. Any place that stocks Weber parts should have them.

If you have a choke, you'll have to make a block-off plate for it.

I enlarged the fuel inlet into the carb slightly, though I don't know how much that actually helps.

It's a good idea to seal the threads of the main and booster venturi holder screws, as they can leak boost. Likewise, make sure any other threads that see positive pressure are either sealed or have an o-ring (aside from the idle mixture screws, obviously).

Also, don't forget to reference your float bowl to the carb hat pressure. Take your FPR reference from the carb hat as well.

Other than that, it's all jetting. Get the biggest needle valve you can; I believe 3.00 is the largest available. You'll need to go up on your main jets and down on your air correctors; 210 main 150 AC is a good starting point, but start with low boost and conservative timing and watch your wideband. You may need to play with emulsion tubes as well to get your mixture right at the transition.
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Old Sep 28, 2011 | 12:02 AM
  #32  
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^^what emulsion tube did you endup using..?^^
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Old Sep 28, 2011 | 12:14 AM
  #33  
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I ended up with F11 as the best compromise of the tubes I have, but my transition is still really rich at low load. I don't know why, but this carb has always liked unusually lean jetting on the idle circuit. I think I'm currently running 50F9 idle jets to give you an idea. On the other hand, I've got 70 AP jets and a blank bypass jet and it still seems to want more AP shot. I dunno. I've kind of lost interest in trying to figure it out since I'll be pulling this motor shortly and dropping in an REW block with EFI. The carb will probably end up in my REPU until I can afford another MegaSquirt, though, so maybe I'll get back into it then.
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Old Sep 28, 2011 | 12:29 AM
  #34  
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From: queens n.y.
cool...my nexts 1st is going to be efi also...i am tired of using a screwdriver to tune my car ..
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Old Sep 28, 2011 | 12:45 AM
  #35  
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Originally Posted by PercentSevenC
The carb will probably end up in my REPU until I can afford another MegaSquirt, though, so maybe I'll get back into it then.
And the turbo will be going in my REPU with a boost prepped Nikki on an R5 13B.

This is an informative thread. I had forgotten about it. Now I have a pic to post in the red truck's Nikki blow through thread.
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Old Sep 28, 2011 | 12:58 AM
  #36  
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It is informative, and I'm glad I had the excuse to post those boost prepping notes before I completely forgot everything about the process (not that it's particularly difficult to figure out). Always feels a little weird reading your own posts after three and a half years, though.
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Old Sep 28, 2011 | 10:50 AM
  #37  
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I have a return spring setup on a DCOE that works excellent, I can link a pick if you would like.
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Old Sep 28, 2011 | 01:08 PM
  #38  
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If you want to, you're more than welcome to. I got mine figured out years ago, though.
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Old Sep 28, 2011 | 08:45 PM
  #39  
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From: WINTER HAVEN, FL
thanks for the help guys my jets arnt to far off from what your running except for my air correction and main jet im runing 175ac and 180main jet but firts thing after work tommorow ill go pick up new ones
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Old Sep 28, 2011 | 08:47 PM
  #40  
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whats a return spring setup?
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Old Sep 29, 2011 | 09:01 AM
  #41  
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Repost...lol

Last edited by 84 GSL; Sep 29, 2011 at 09:03 AM.
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