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Discussion Starter #1 (Edited)
Anybody who has a 70's Rochester knows it's a pain to maintain, and way too complicated. Mine was rebuild last year, but recently it started acting up, and decided that it no longer wanted to cooperate with my timing. I had grown to absolutely hate the Rochester so I decided to replace it.

I chose to go with a brand new Weber 38 DGES Two Barrel Synchronus Carburetor.

Why Weber? Because, they are super simple, sturdy, and most of all dependable. They can be tuned on the side of the road in a pinch.

The 38 is an ideal size if you are planning to upgrade to a better intake/header combo in the future. If you want to stick with the restrictive OEM intake/header
then you may want the 32/36 progressive carb (or any other smaller two barrel carb).

Onwards with the job...

Parts needed:

-Weber 2bbl carb of your choosing.
-Appropriate 2 inch or 4 inch air filter kit (I am pretty sure the 4 inch will fit under the hood...).
- Weber 1bbl to 2bbl adapter kit (comes with hardware and gaskets).
- Weber cable linkage kit.
- Vacuum seal cap multi pack (the little nipple cap things).
- In-line fuel filter kit.
- Flat female electrical connector (only if you opted for electric choke).
- Loop end electrical connector (only if you opted for electric choke).
- Decent electrical wire, 18 gauge etc (only if you opted for electric choke).

- You may need a few feet of fuel line, I replace my metal tube line from the pump a few years ago with rubber fuel hose.

Some tools needed that you may not have handy:

- 9/16 socket and 6 inch extension
- 9/16 wrench
- 8mm socket
- 2x 13mm wrenches
- Angle grinder with cutting wheel
- Timing light




Lets get wrenching!

Say goodbye to this mess:


New parts:


Old and new:


Bottom is fuel in, not sure what the top does, it didn't produce vac or blow, so I capped it.


In for your vacuum advance line.


You'll need to install the cable connector plate from your cable kit. Remove the nut and washer, the equipped connector, and install the one from the kit as show:







To install the adapter you'll need to take the angle grinder and remove approximately 1/4 inch off the left (farthest from engine) bolt. The bolt is too tall and interferes with the random brass fitting on the adapter. I'm not sure what the fitting is for, I capped it off.




Remove the oem cable linkage assembly, you don't need it.




Bolt the Weber onto the adapter using the 13 mm bolts provided (this is where you need the two wrenches. Clip the very end off of the accelerator cable and remove all the plastic stuff, also remove the cable support from the manifold, it doesn't line up with the Weber. Install the cable lock into the cable linkage plate. Run the cable through and lock it in with the screw. There is more motion in the pedal than there is in the carb itself, so calibrate accordingly. Take the old feedback spring from the Rochester (the one that connected to the valve cover bolt) and connect it to the old choke bolt.


Straighten out the vacuum advanced metal tube and plug the rubber hose at the end into the vacuum advance tube under the electronic choke on the back that was pictured earlier. Install your fuel filter. I put mine in before the mechanical fuel pump, it's out of the way and keeps your pump cleaner.


Plug in your fuel line (this is where replacing the oem metal one with the rubber one may be advised).





If you opted for the electronic choke, run a wire from the choke to the rear connector (12v) on the coil.

The OEM timing for idle suggests 700 rpm at 4 degrees, we did 700rpm at 7-8 degrees with no issue.

This carb is great, I'm getting a nice increase in low to mid-range torque and power. Top end could use improvement, So some more tuning is necessary for wide open throttle.

The mixture screws are located mid carb on the front and rear, then can be turned by finger.

Day-to-day:

Starting cold: Give a slight tap on the gas prior to key turn, should start right up.

Starting hot: Don't touch the gas.

Shut down: Let idle for a second, do not blip the throttle or it will diesel.

Enjoy :cool:
 

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Mr. Tom,
excellent write up Sir.
If you don't mind, could you please give a dollar figure as to what this swap cost you ?

Obviously everyones milage will vary on prices in their A.O.

Thank you,
Stu
 

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Discussion Starter #3
Mr. Tom,
excellent write up Sir.
If you don't mind, could you please give a dollar figure as to what this swap cost you ?

Obviously everyones milage will vary on prices in their A.O.

Thank you,
Stu
Shipped, the carb, adapter, and linkage parts ran about $415. The carb was about $380 new from Weber direct. The 32/36 carb was a lot cheeper, but I wanted more flow because I plan on getting the Clifford header/intake combo in the future.

Once I get it tuned out, I should be able to grab some good mpg figures. The old Rochester gave me approximately 16 mpg. The Weber may actually get better mileage. It's so much more responsive, and doesn't require pedal mashing for hills.

-Stephen
 

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Great write up! I am currently debating between this http://www.ebay.com/itm/360402264949?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_1030wt_952

And the single barrel rebuilt units from an auto supply chain. My current single barrel is leaking gas. I have a bone stock 194 with 1500 miles on a rebuild. Do you think the 2bbl swap is worth it? I'm hoping to keep the underhood area looking as stock as possible so I'll probably cut the bottom of the single barrel air cleaner and weld a new piece that works for the set up above. Any suggestions?
 

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I did this exact change on my 250, but if you want to save $75, try this site.
I am not affiliated with them in any way, just bought my parts from them, cost around $255.

http://www.webercarbsdirect.com/




Here's how it turned out.
Thanks for the website! I still want to use my stock linkage, not cable. I am wondering if the jeep linkage on the website can be made to work for my application? Also, is this carburetor "sync linked" (not sure exactly what that means) Thanks for any advice.
 
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