2bbl to 4bbl conversion

[Camman.8]

Having a problem figuring out which throttle cable/kickdown bracket to use for a Holly Carb 4bbl on my 318. I installed the bracket by Holly on the carb but the throttle bracket I got for a 340 does not fit my intake bolt pattern. Which one do I use.
The one I have:

https://cdn.classicindustries.com/assets/images/ProductImg/M/MF224.JPG

Or do I need this one?

https://cdn.classicindustries.com/assets/images/ProductImg/M/MN2542.JPG

[tparker]

This is a tough one I have been fighting with, but with a avs style carb. Of course, it depends. I am not sure how much impact the Holly has on the setup vs the carter/edlebrock. There are 3 kickdown linkage options that I am aware of. My 318 had a single linkage rod that when from the throttle bracket all the way down to the transmission. The second seems a more difficult to find the the correct setup as there are a lot of options and not ever one is selling the correct piece. It has 3 rods (one at carb, one at trans, and one to connect the two. It also has two bell cranks, which are basically pivots. The third option is the Lokar (and variants) cable.

There are several different throttle brackets depending on which setup you have. The first one with the round bar sticking out should be for the 3 piece linkage and goes on the last two bolts of the manifold. The second one should be the one for the single rod kickdown and if I remember correctly it is moved up one set of bolts. They only fit in one location.

 

[Camman.8]

Thanks tparker. I believe You are correct. I just got off the phone with customer service at MOPAR parts and they explained it as you did. I have the one piece kick down rod so I would need the second one I listed. Most places that sell them didn't explain  the difference well but they said with the 2nd one listed will accommodate the stock throttle cable but I may need to modify the kick down rod that hooks to the carb linkage. As far as where to mount it I think you're right. I may have to move it up to the next set of bolts. I'm going to order the second bracket and return the first bracket. Once I get it I'll know more about where it mounts.
Thanks so much!

[Bullitt-]

I have an OE 73 340-four barrel that I think would use the second pictured bracket

 

[Chryco Psycho]

Check with Mancini , they should have an adjustable 1 for it .

[Camman.8]

Thank. Great info. This gives me a better understanding of how to set the kick down linkage up. Is this the starting point or what it should be after it's tested and adjusted for the shift points?

[tparker]

here is a video that might help with the adjustment
https://www.youtube.com/watch?v=FY9WTWayCC8

[Camman.8]

Thanks for all the help. When I bought this car the previous owner had the engine rebuilt and added the Holly 600 cfm carb, intake and mild cam. It runs great but it didn't have full throttle. the secondarys never opened up and the shift points are of just a bit off with no kick down when needed. With all the help here I'm sure I can make come to life.

[tparker]

using the wrong parts can cause issues with both the kickdown in the trans and/or carb throttle positioning. There is a bit of geometry involved. It is possible for the linkage to max out and prevent the carb from opening up completely or the kickdown lever not being pushed back far enough. There are several things that would cause this. The video goes over the adjustments. The key thing from my understanding is there should be a one to one relationship with the throttle on the carb and the kickdown lever on the transmission. If one moves one inch, the other should as well. At wide open, the kickdown lever should be maxed out, or just shy I think. So having the correct linkages, carb adapters, bell cranks, and kickdown lever would all play a role in a correct setup.

Please correct me if I don't have this all down. I've been trying to figure it out lately to fix my own issues. LOL

[7212Mopar]

Adjust the throttle cable and kick down independently. The throttle cable should have the correct length and allow the throttle to open fully including the secondary. Best place to get the right cable is Roseville. Stock kick down linkage can be tricky on non stock application. This problem can easily be solved with cable kickdown. You can use Lokar cable or cable from Bouchillon Performance. The drawback is that you lose the factory looks

[Camman.8]

Thanks for the help y'all. The video helps a lot. If I can't get it right I'll go with a longer throttle cable and Lokar step down cable. The photo is from we recently restored  the car and made the motor look pretty.

[MoparLeo]

I read the post and didn't read anywhere on what intake manifold are you using?
When converting from 2 bbl to 4 bbl with the original 2 piece kick down rod, the rod from the manifold to trans will be too short. You either will need to cut it and weld a short section to it or get the correct rod.
 The 4 bbl manifold moves the linkage forward due to the primary  butterflies  now being in front of the center of the manifold like the 2 bbl manifold was.
Also you may notice in the other posted pictures that the linkages are not exactly in alignment. This is because the parts used by the other users are not all of the correct parts that should be used.
Remember that whenever you are adapting something, that unless you have all of the correct parts to do the changeover in hand or are now using non factory parts, you will sometimes need to try different parts to get everything in proper alignment.
 Everything should be parallel and in alignment for smooth operation.
Show some pictures of your setup. Best way to get good help.
Never drive the car without the kick down rod connected .
 Its job is to control the line pressure inside the trans.
You can damage the transmission if it is not connected or way out of adjustment.
 These procedures are found in the Factory Service Manual that every car enthusiast should be referring to for any standard services.
 This is the Manual that was used at the Dealership to service the cars when they were new.
Free downloads are found here in our reference library.

[Camman.8]

MorparLeo
the 2nd owner of the car (I'm the 3rd) covered it to 4bbl. It never was right. I was just looking at the documents he gave me and it looks like he put on a 360 4bbl intake.
After I put Holly Chrysler adopter on the carb it moved the kick down lever over at quite an angle. I moved it to the outside of the hing bracket and it's nice and straight now.
To make the rod longer would a 73-74 340-360 motor be longer?
What it is now.

[Chryco Psycho]

I would also build something to hold the wiring up off the intake by the valve cover , sitting on the intake they can melt & short out , don't ask how I know !

[tparker]

The length of the motor won't change based on the year. The 4 bbl is moved further forward than the 2 bbl. That is the problem. It's hard to tell from the photo but it looks like the throttle linkage with the large slot (not sure what its called) is angled. It should be mostly straight. Also, that bolt in the middle of the slot might be dangerous. The slow is there incase the kick down linkage gets stuck in what would be wide open throttle. If that happens, the slot allows the throttle to go back to the idle position. The screw has changed the geometry and probably would keep the throttle open if the linkage gets stuck. I fabricated a new one, it wasn't hard. Just used a drill and a dremel to cut it out and then filed it smooth.

I was playing with just fabricating the the piece that connects to the throttle with the long slot. I don't see why you would need too cut the 2 bbl kick down rod and weld a piece to it to extend it as only the carb moved foward. It seems like you just need to extend the piece that connects the kickdown rod to the carb. But mine was binding up and I couldn't see what the problem was. So I just figured I would just go get the proper 3 piece version. How hard could that be   

As a side note, I was some how able to connect the 318 2bbl single kickdown rod to a thermoquad. I have no idea how I made it work. I can't duplicate it with the Eddlebrock. They both seem to have the same form factor for the throttle, butterflys, and bolt holes. But I swear I had it working, LOL