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914World.com _ 914World Garage _ Weber IDF 40 jet sizes

Posted by: wayne1234 Feb 2 2010, 04:26 PM

Well I tore down the carbs, ther was some junk in it even though it was recently rebuilt by PO, Well it is a 2.0 with a mild cam And it has 1.7 heads, I havent ordered the "tech" book yet. should I get the weber tech book or the haynes weber book? but I think the only thing I need to use the book for is setting the float level... are there any other tricks in the book? So when I order the rebuild kit I want to make sure I have the necessary jets if they need to be changed.. the car ran a little rich, but who knows if the air jets were clogged throwing off the mix... so it currently has on the main jets stacks in the top of the carb the body says 200( Air i assume) then the tip says GMCI 130, Then on the side of the carb (the idle jets I assume) say 50 .... So what do you guys think I should be running? where is the best place to get the stuff???

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Posted by: tomeric914 Feb 2 2010, 04:30 PM

200/F11/130 will get "it" running. Then you need to drive it to get "it" right.

If you have it apart, make sure the floats are set right. If the floats are off, it will affect the emulsion tube transfer from idle to progression to power circuits.

Posted by: wayne1234 Feb 2 2010, 04:52 PM

How do I set the floats. I have read so many things saying that the book is wrong? how do I set it with out any special tools someone please point me in the right direction

Posted by: jmill Feb 2 2010, 05:23 PM

You don't need special tools if you have a metric ruler. If not 10 mm is @ .39 inches. Use the back side of your calipers.

http://www.worldwidemetric.com/metcal.htm

Your jetting is in the ballpark. With the F11 you have to get your float level right. If you set it low you'll have lean transition issues.

Posted by: wayne1234 Feb 2 2010, 05:40 PM

thanks Il post up some more as I'm into it im sure I will have more questions... maybe I should go mega squirt

Posted by: Vacca Rabite Feb 2 2010, 06:25 PM

Get the weber tech book. There is a ton of information in there that i very handy when you are learning about carbs. Also, there are more parts to your jet stack.

http://www.914world.com/bbs2/index.php?showtopic=101860
this thread has all the bits exploded so you can see where they hide.

zach

Posted by: wayne1234 Feb 2 2010, 07:17 PM

thanks for the link, I have had the jet stack apart ,, but I didnt know the inlet valve had a ball in it or another orafice... my buddy did the tank clean at work so everything is clean, but I'm gonna take the inlet valve out and check it now

Posted by: Van Feb 2 2010, 07:57 PM

The carb tech articles on this site are pretty good: http://www.aircooled.net/gnrlsite/resource/articles.htm

I'd pass on the Weber Tech Manual - IMHO, it's outdated and has incorrect information (like setting the float heights!!). There are some nice diagrams and illustrations, but I've found it of limited use.

Posted by: Jake Raby Feb 2 2010, 08:31 PM

Jetting is directly impacted by venturi size more than anything else. What size venturis are in the carbs?

For vents to 36mm the formula is vent diameter multiplied by 4 for the target sea level main jetting.

200 airs will run most combos well, the F11 is standard for a street engine and a 55 idle works every time...

everything is related to venturi diameter.

Posted by: wayne1234 Feb 2 2010, 11:07 PM

1 inlet valve was bad, it was totally clogged and stuck, we tore it up getting it out but at least it was clogged, so it was at least worth the trouble... venturi size is a 28 Am I headed in the right direction , I just want to order all parts at once, And where do I order from????? thanks Wayne

Posted by: Vacca Rabite Feb 3 2010, 09:32 AM

Aircooled.net usually has all the carb stuff you need.
As does Weber Carbs Direct (usually)
Jake might.
Ace (Art Threan's shop) does.
If you have local bug shops, they usually have the stuff too.

Zach

Posted by: jmill Feb 3 2010, 10:32 AM

The 130's will be a bit too big for 28's. I assumed you had the standard 32's. It'll be rich, but it will run. 120's would be my best guess. With the F11 I like going a tad bigger on the mains for a better transition and then lean it up at higher velocities with the AC jet.

Posted by: Jake Raby Feb 3 2010, 01:06 PM

With the location you are in I'd say a 120 would be good as well.. Here I optimize a 28 vent with a 115 main, but thats at 2,000'

130 is way too fat.. I use a 130 for 32-34mm vents

Posted by: wayne1234 Feb 3 2010, 02:08 PM

So stay with the 50 idle jets, And is the 55 inlet jet on the bottom of bowl, is that good? Thanks

Posted by: wayne1234 Feb 3 2010, 06:29 PM

Is the 55 inlet jet good, I plan on ordering a bunch of stuff tomorrow,,, Thanks guys