SB 318 to BB 383 Conversion Unanswered Questions? • The Dodge Challenger Message Board

by **cudabite** » 27 Jun 2007 18:40

Hi there guys, so I've been reading around for a while on how to do a SB 318/904 to 383/727 swap. Now correct me if I'm wrong but it seems that all I'll need is the shorten my driveshaft, install the yoke for the 727, buy new motor mounts for the 383 and thats it? The reason I'm asking is because I was talking to my mechanic and he said I will need new power steering pump housing, and that my transmission might not clear correctly since the car was fitted with the 904, and other misc. odds and ends?

My question stands, will I need new powering housing? Is there anything I'm totally missing here, or is the swap pretty straight forward and I'm head on? I've got all the stock components from the 318, and I'm ready to go to my 383, what else will I need?

by **Eddie** » 27 Jun 2007 19:15

Sounds good so far. Have you addressed cooling? Is the radiator large enough for your perfirmance goals? Does the upper/lower hoses "connect" What have you done to the suspension? Those torsion bars were meant for a lighter engine, are you gonna just use it for drag racing or do you want a dual purpose car that turns well?Does it have an anything less than a 8 3/4 rear end?

by **dave-r** » 27 Jun 2007 20:54

The only difference between the 318 Challenger and the 383 is the engine and box. The rest of the car is the same. I helped a friend do this conversion many years ago before I owned a Challenger myself. It was a very straightforward swap.

The K-frame (engine cross-member) is the same. So all you need is the 383 Challenger engine mounts which are easy to get.

The brackets that fit the engine are different to a 318. So you need the 383 alternator and power steering brackets. But the units themselves are the same. They came in different sizes and makes but I am sure they all fit and will work.

Pretty sure we used the existing trans mount too.

As Eddie says. Stiffer suspension and disc brakes up front might be a good idea. (you don't say what year Challenger it is) Plus the rear axle might need an upgrade if it is not an 8.75 diff.

by **cudabite** » 27 Jun 2007 23:29

Okay awesome thanks for the responses guys. Yeah I'm doing the disc brake upgrade in these coming up weeks, I've got all the stuff off a 75 A-body plus had to buy a master cylinder and proportioning valve. I do have an 8 3/4 rear end, so I think I'll be fine with that. It's a 1970 Challenger. From the factory it was ordered with "Rallye Suspension." Whatever that means. I know that because I read the build sheet I've got with it, plus my VIN# on the car says it as well. What did Rallye suspension give me? I'm definately going to be putting in a new radiator. It's going to be used mostly street, its my daily driver. (more like every other day). What size torsion bars should I go with and who's a good vendor? I'm buying the Mopar Street/Strip Suspension Kit from JustSuspension, should I go ahead and get bigger torsion bars as well? My friends dad suggested bigger springs in the front, did he mean torsion bars? I want this thing to be quick off the line and a cruiser, but definately something that corners and moves well outside of a straight line for daily driving purposes. Also where can I buy the 383 alternator and power steering brackets? Thanks for the quick responses!

by **dave-r** » 28 Jun 2007 9:20

cudabite wrote:It's a 1970 Challenger. From the factory it was ordered with "Rallye Suspension." Whatever that means.

It means it came with heavy duty suspension. So your front torsion bars might be up to stock 383- 4bbl rates anyway.

Check out the diameter of the torsion bars. If they are 0.90-inch you are good to go. Although an upgrage to hemi springs front and back will improve handling. As well as bigger front and rear sway bars.

A rear sway bar makes a big difference.

What did Rallye suspension give me?

What is the actual code you have?

JustSuspension are probably your best bet for everything.

Also where can I buy the 383 alternator and power steering brackets? Thanks for the quick responses!

Maybe Year One?

by **Eddie** » 28 Jun 2007 12:40

For brackets and pulleys check Hoffmans winners circle or Bouchillion Performance.

by **dave-r** » 28 Jun 2007 13:19

How come you know all the places to spend money at Eddie? :lol:

by **Eddie** » 28 Jun 2007 19:19

by **cudabite** » 28 Jun 2007 23:51

Awesome, thanks for the responses guys. Dave - I'll check when I get home and get ahold of my broadcast sheet to see the exact # for my Rallye Suspension. Eddie - Thanks for those websites, it seems that Hoffmans is cheaper, so I'll probably go with them for that. Woo, I'm going to europe for a month in july, so I hope to have this whole conversion and suspension upgrade done by mid to late august. We'll see how far my funds can get me haha.

by **cudabite** » 01 Jul 2007 19:28

Okay, so off of my broadcast sheet this is what it says for stuff I find interesting:

Torsion Bar: LT: 779, RT: 778

Rear Spring LT: 043, RT: 043

Under the S section for Suspension - Steering it reads this:

1-Susp and below that is the number 3
31- Sway Bar: Beneath that it says 1
then at the bottom of the entire thing beneath all the standard broadcasting stuff it says KS and beneath that 01 SPECIAL HANDLING CAR.

Does this help anyone out? If need be, I can scan the broadcast sheet for you if this doesn't make sense, I tried the best I can hehe. Any help decoding what exactly these mean would be awesome.

by **cudabite** » 01 Jul 2007 20:56

Okay so I researched it a bit, and this is what I've found so far. (Answering my own questions)

For my suspension it seems that I have the S13 & S31 Broadcast Codes, signifying (by what I read off the forums) that I should have Rallye Suspension w/ sway bar and a Front Sway Bar. I'm guessing this should signify I have a front and rear sway bar, but I looked in the rear and I don't think I have one back there. I think I have one on the front, but I don't really know where its mounted or how to be sure if it is a sway bar or not?