engine swap SB to BB

[JurgenS]

I will be changing the 318 in my 73 Barracuda for a stroked 400 B block. It's my 1st Mopar and I only have it a few weeks, not much experience.... I was wondering what else needs to be changed when going from a small block to a big block. I was told the motor mounts are different but what about all the other things that will have to changed, like, the transmission, accessories drive system, water pump, distributor, ....

Any advice, links to good sources, would be very helpful.

 

[rklein71]

Distributor, accessory brackets, transmission, water pump, exhaust, intake, oil pan, radiator, valve covers, all different.

 

[JurgenS]

Bummer I have to change the transmission too. I got a quote from SST for a Tremec Magnum but costing almost 10K, it is over budget...

 

[340challconvert]

Probably need to upgrade torsion bars with the added weight over the front wheels. The big blocks had higher rated bars up front.

Torsion Bar Identification Diameter of the bar is listed in inches.
225 six =0.86
318 1970 = 0.88
1971- 1974 = 0.86
HD 1970-1974 = 0.90

340 1970-71 = 0.90
1972-1973 = 0.86 Your car
HD 1970 - 1973 = 0.90

360 1974 = 0.86
HD 1974 = 0.90

383-2bbl 1970-1971 = 0.86
HD 1970-1971 = 0.90
383-4bbl = 0.90

440 1970 = 0.92
1971 = 0.90

426 Hemi 1970-1971 = 0.92

778 / 779 or 780/781 are the large bars the number will be cast on one or both ends

 

[JurgenS]

Is the driveshaft the same when I keep an automatic transmission?

 

[340challconvert]

The 904 transmission which would be the trans with your 318 is 31" in length. The 727 is 35" in length. The driveshaft would have to be shortened to work with the big block. I believe that the yoke would also have to be changed since the yoke is smaller on the the 904.

]

 

[340challconvert]

This pic shows the differences of yoke sizes!

 

[704406]

On top of everything else that has been mentioned, One additional thing people forget about when doing swaps is the transmission kick down linkage, it's totally different from a 904 to a 727 trans, and there are different throttle linkage and throttle cable brackets.
If you have a 2 barrel carb, linkage is different for a 4 barrel carb.

 

[JurgenS]

Will need to look into that because it will have EFI.

 

[DrEamer]

Any real reason for going to the stroked 400 other then power. Just wondering since you can get over 500 horse power and torque out of a stroked 360, and have most of the parts you have fit. I ask only because I considered doing the 400 myself, and understand the draw to doing it. One other note, if you run aluminum heads, water pump, and housing, your engine weight is suppose to be close to running a cast small block. Then again, you may have already knew that.

 

[JurgenS]

I've always wanted to have a big block once, that's the only reason. The current 318 was recently overhauled so actually there's no reason to replace it. When I bought this car last September, I also searched the internet for performance upgrades. I found out that the 400 was a strong block and therefore I searched and bought one. At the same time I also bought the rotating assembly from 440source including aluminum Trickflow heads. So there's no way back now! It will take a while though to complete it, I also want EFI and don't have any of these parts yet.

 

[DrEamer]

Sounds like the set up I was going after. I had an engine to use, but ended up selling it for more then I payed for it. Also, what size of stroker are you going with, 451,470, 500? As far as a transmission, you might consider getting 727 or 833, and putting a gear vendors overdrive on it. Not cheap, but less then the SST units.

 

[JurgenS]

512
I've been looking at gear vendors too but I couldn't find what I was looking for but getting a built automatic transmissions and a gear vendors might bump up the price to the same level as SST.