Re: [Amc-list] Weber Carbs for the 258

[Frank Swygert <farna@xxxxxxx>]

For staters, a good condition, well working BBD is about as good as any other carburetor. I'm guessing yours is just worn out and a simple kit probably won't fix it. You could go to a good carb builder (antique specialist now!) and get one that has bushed throttle shaft holes and such and probably be happy with the results. The only time changing the carb to a newer model really makes a difference is when the original is worn out. 

I'm using a Clifford intake and a 390 Holley now. I was a bit disappointed. No more power than a good BBD at low speeds at all. When the truck (an 83 J-10 that had the electronics pulled and an older non-electronic BBD installed) is under a load I do get a little extra boost. Not as in "passing power", more as in "easier to hold speed pulling up a hill". If you're going to go with a 4V you really need to upgrade the cam, and/or use a 450-500 cfm carb. With the stock cam I don't think you'd get much boost even with a bigger carb though. 

The BBD on AMC sixes is a 190 cfm according to some Carter documentation. I know the 230 cfm number (or something like that) has been bandied around, but that's apparently for the larger venturi Chrysler 318 model. A cheap small power boost is to use the 80s Chrysler 318 center section (often found on Volare body New Yorkers and Diplomats) with the AMC base and top. The throttle plates are the same size for both sizes, just the venturis in the center section are different -- the 318 version is 1/16" larger in diameter (or is it 1/8"?) than the AMC. 

With any change in carb you have a change in linkage. I had to get a longer throttle cable and make an anchor point for the cable. Because I used a salvage yard cable I also had to bend the pedal arm. Luckily the Jeep pedal arm is nothing but a steel rod bent to shape -- giving it a little more travel was as easy as clamping it in a vice and bending. Since the Spirit uses a cable it won't be difficult to make the original pedal work. 

Check Jeep sites for recommendations on Weber carbs. Tom has some experience with the conversion, I'm sure he'll chime in. 

---------------
Date: Tue, 6 May 2008 21:35:10 -0400
From: "Clifton  Danley" <am401@xxxxxxxxxxx>

I need to replace the dreaded BBD on my 258 Spirit, and have found several 
variants of the Weber 2-barrel. Can you answer some questions?

Which one will work best on a stock 258?
Will it fit a stock manifold without an adapter?
Will I need new linkage?
Would a Clifford intake and 390 Holley work better?

-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)

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