2 BBL to 4 BBL Swap Advice Needed

[Road_Runner]

I'm gathering parts to swap the tiny 2 barrel carb on my 73 Barracuda 318 to a 4 barrel.  So far I picked up a Mopar Performance dual plane M1 intake, an original 73 340 air cleaner and I'm deciding on either an Edelbrock performer or Thunder AVS carb.  I've also got a 904 automatic, so I'll need to hook up the stock kick down linkage.  Anyone done this swap & can tell me exactly what extra pieces I'm going to need to hook up the throttle, kick-down linkages, assorted vacuum lines, fuel line (other than just running a section of rubber hose?).   I'd like to gather all the parts first than do this all in a day.

Thanks in advance, Jim

[Road_Runner]

And any advice as to which Edelebrock carb to go with would be appreciated as well.  Initially, this is going on a stock 318 with a decent dual exhaust setup, ultimately I'll either rebuild te 318 for more performance or step up to a 340 or 360.

thanks, Jim

[Chryco Psycho]

the Thunder series carbs are afr superior to the AFB style , You will need the fuel line kit or you can just run rubber hose to the nipple , there is a linkage adapter that Eddy makes for the mopars that put the throttle pin in the correct position for the factory 4 bbl throttle cable & kickdown linkage going from a 2 bbl though you may need different throttle braket & upper kickdown link to work correctly

[Road_Runner]

the Thunder series carbs are afr superior to the AFB style , You will need the fuel line kit or you can just run rubber hose to the nipple , there is a linkage adapter that Eddy makes for the mopars that put the throttle pin in the correct position for the factory 4 bbl throttle cable & kickdown linkage going from a 2 bbl though you may need different throttle braket & upper kickdown link to work correctly

I appreciate the info, thanks.

[Super Blue 72]

If I remember correctly the intake gasket has rubber seals front and rear.  Keep and eye on these as I remember when I did the intake swap about 20+ years ago the fron seal squeezed out, possibly from using too much silicone cement. 

[dodge freak 2]

Most just used RTV on the rails and no cork gasket.

Oh be sure to remove the pin on the rails, if its a virgie motor it have them...a motor that never been opened up since new.

Yeah go with the Thunder 650...but they aren't cheap..they have been showing up on ebay lately--maybe were x-mas gifts, don't know..oh not those buy it now BS ads from the speed shops but regular members selling stuff not wasting space 

[Road_Runner]

Most just used RTV on the rails and no cork gasket.

Oh be sure to remove the pin on the rails, if its a virgie motor it have them...a motor that never been opened up since new.

Yeah go with the Thunder 650...but they aren't cheap..they have been showing up on ebay lately--maybe were x-mas gifts, don't know..oh not those buy it now BS ads from the speed shops but regular members selling stuff not wasting space

Thanks for the advice on the end gaskets.  I've replaced big block intakes, but they don't have these and use a pan gasket instead.  Sounds like I'm definitely going for the Thunder 650.

Thanks again, Jim

[67vertman]

I did pretty much the same thing to my 318 last year.  You will need a 4 barrel throttle bracket, and I modified my 2 barrel kickdown linkage so the lenght would be correct.  Very happy with the results.




The four barrel linkage is slightly taller and angled some compared to the 2 barrel one.

[Road_Runner]

I did pretty much the same thing to my 318 last year.  You will need a 4 barrel throttle bracket, and I modified my 2 barrel kickdown linkage so the lenght would be correct.  Very happy with the results.




The four barrel linkage is slightly taller and angled some compared to the 2 barrel one.

Perfect!  Thanks for the info & the pics!

Later, Jim

[dodge freak 2]

The 500 Thunder might be best now but the 650 will work fine with the tighter tension on the air valve spring setting.

[RusTy/SE]

I put an Edelbrock 1405 carb with 8021 mopar linkage adapter on a stock '87 360 when the original 318 was replaced in my 86 D250 back in July of '07 while keeping the original 727 trans. Yours may be different but i was able to order the one piece 4-bbl kickdown rod part #4287963 straight from the dealer for that application if you choose to go that route.

 

[Road_Runner]

The 500 Thunder might be best now but the 650 will work fine with the tighter tension on the air valve spring setting.

I saw that the Thunder Carb had that feature, sounds pretty cool.  I also agree that the 500 cfm would work fine for the 318 as is, but wouldn't want to try & run that on anything stronger.

Thanks, Jim

[Road_Runner]

I put an Edelbrock 1405 carb with 8021 mopar linkage adapter on a stock '87 360 when the original 318 was replaced in my 86 D250 back in July of '07 while keeping the original 727 trans. Yours may be different but i was able to order the one piece 4-bbl kickdown rod part #4287963 straight from the dealer for that application if you choose to go that route.

 

I'm looking at the 1806 650 AVS to retain the electric choke.  I also found an original 340 4 bbl throttle linkage & kickdown lever that I'm hoping will do the trick as long as I get the extra Chrysler bracket from Edelbrock.  Does anyone know if I'm going to have to run some type of spacer to seal the Thunder AVS to my square bore Mopar Performance M1 manifold?  Seems like I had to go to a Holley years ago when I put a M1 on my Roadrunner for this reason because I couldn't use a spacer and still fit under the Airgrabber hood.

Later, Jim

[dodge freak 2]

If you could post a picture of the carb flange on the M1 we could tell you for sure. Edelbock does sell a 1/8 spacer to seal the Performer intake flange--plus the Edelbrock carb is a tad shorter in height than the Holley.

Might not need it thou..what carb are you running now? 

[Road_Runner]

If you could post a picture of the carb flange on the M1 we could tell you for sure. Edelbock does sell a 1/8 spacer to seal the Performer intake flange--plus the Edelbrock carb is a tad shorter in height than the Holley.

Might not need it thou..what carb are you running now?

I'll try to post a pic, right now I'm running the stock 2 bbl & intake that came on it in 1973.