318 2 barrel to 4 Barrel Conversion: Necessary Brackets and Linkages?

[74Runneer]

I have a 74 Road Runner with a 318 and an auto in it. The previous owner put an Edelbrock 1406 600 cfm 4 bbl carb in it with a performer intake and I've been told that It doesn't have the correct linkage or bracket. They say I still have the 2 bbl hardware on it. Can anyone tell me what hardware I need and where I can get it? I'm not exactly sure which is the 2 bbl hardware that I need to update.

Here is the only picture that I have of it right now, I'll take a better picture and upload it when I get the chance to.

Thanks in advance!

View attachment 20160617_223756 (1).jpg

 

[PurpleBeeper]

I can't see your picture. Here's what I suggest you do. First, take a look at the setup on your car right now. When you put your foot down to the floor on the gas pedal, does it open the carb up completely? When you take your foot off the gas pedal, does the carb close completely without anything getting in the way or hanging up? If the answer to both questions is "yes", then leave it alone. If either answer is "no" then look for a throttle linkage and/or gas pedal cable from a 340 or 360 4bbl. car and it should fit or be very, very close.

 

[YY1]

True 4v brackets are hard to find.

Limited 340 production and somewhat limited 360-4 production.

Easiest source would likely be a late 70's Cordoba or maybe a truck/van/motor home.

I agree, if it's working don't f with it.

One way to mod the 2v is to add a short link to the cable from flat bar stock, and weld in a length of all-thread to the kick down rod.

 

[idrivemopar]

Here is what the stock linkages look like on a 73 340 auto. The one thing you cant see in the photo is the throttle cable, which attaches on the inside of the bar where both springs connect.

 

[74Runneer]

Wow, that is one clean engine. I reuploaded the picture as an attachment, maybe that will work. I'll check to see if the carb completely opens and closes.

 

[cudak888]

This is the 4-barrel linkage I have on my 360 (technically a Magnum 5.9 at this point). This linkage is essentially identical to the 1972 and earlier 340 design (obviously, different from the '73 version above):

The carb-to-bellcrank arm was originally a non-adjustable one - I believe from a later '80s application (e.g., Ramcharger). Even though I really didn't have to, I cut the end off of it and threaded it to accept the 318's original adjustable slot so it'd look a bit more like an original part. Here's a photo of a 340 from the internet with the non-adjustable version like what I started with:

P.S.: Even though this setup generally works well, I'll still get a hard bang out of the 904 if I let off the gas just before a shift point - and I invariably lift off seconds before it gets there. I have to figure out if it's the trans or me that's gone wrong. Thing is, my Valiant does the same exact thing, and the points feel adjusted perfectly if I don't lift off. Hey, it's the price to pay for "still learning." EDIT: Looks like this is normal. Disregard the digression...

-Kurt

 

[BeatersRus]

your kickdown setup looks wrong kurt?
i dont see a spring for the kickdown return and,
That slotted linkage looks to be way too close to your throttle arm.
thats prolly why you have to let off to get your bangshift.
but hey i could be totally wrong someone will chime in.
thats just what i see in pic

 

[cudak888]

your kickdown setup looks wrong kurt?
i dont see a spring for the kickdown return and,
That slotted linkage looks to be way too close to your throttle arm.
thats prolly why you have to let off to get your bangshift.
but hey i could be totally wrong someone will chime in.
thats just what i see in pic

If that's so, then everyone with a pre-'72 340 on the internet has their kickdown set up wrong. The FSM pics I have handy don't show the 4-barrel LA variant, but both the standard LA kickdown and 383 are oriented the same way I have mine - with exception that the 4-barrel kickdown runs straight and attaches to the inner right fork of the bellcrank, not the outer right:

And another 340 example from the internet:

Also found these conversations at FABO which answered a lot about the bangshift
at throttle liftoff:

http://www.forabodiesonly.com/mopar/threads/clunk-noise-when-shifting-upwards.277672/

http://www.forabodiesonly.com/mopar/threads/low-speed-clank-when-letting-off-gas.365559/

-Kurt

 

[toolmanmike]

This may help.

http://www.forabodiesonly.com/mopar/threads/2-barrel-to-4-barrel-conversion.338417/#post-1971105243

 

[BeatersRus]

okay i went and scoped every one of those links annnnnd.
they all come back to the line pressure/kickdown...
at least thats what im getting.

as far as your setup,im just not sure.
thats why i posted it like that.
but,it seems like you had to make very sure that your kickdown was adjusted perfectly and it wasnt that tight against the arm.
after seeing the other pics im not sure.
seems like i read awhile back about lokar or another competitor had a full description of how-to setup the kickdowns.

the main things were check for full movement of kickdown lever at trans when carb is opened wide.
no binding or stopping of throttle arm.
so if thats a proper setup,the only thing i can think of,is to check your kickdown lever travel and adjust that thread piece to see how your tranny responds.

also,the way you did your arm,for the kickdown,
was the way we used to do it bitd.

 

[mrsnicks]

I did the same conversion and used a bouchellon performance kickdown linkage kit.

http://bouchillonperformance.com/inc/sdetail/589