4.3 gm engine into Into an Iron Duke with TorqueFlite a904

[amosende]

I'm surprised there isn't more postings on this.

I have an 82 SX4 with a 2.5 Iron Duke (SBC) into a Torqueflite a904 automatic transmission.

1) Since the SBC pattern is the same what is it going to take to upgrade to a 4.3 Vortec or 4.3 TBI?
2) Which engine should I go for a TBI or the newer Vortec? 
3) Will The Torqueflite a904 handle the 190 HP upgrade?


Cheers Mates.

[IowaEagle]

The least I could do was give you a Thumbs Up because you didn't have any.  904's in good working order will handle that much HP, they are used on the strip by some.  Other than that I don't know diddly squat about GM stuff.

[eaglefreek]

I haven't seen any documented swaps that replaced the Iron Duke and retained the 904. I too am surprised there aren't more. You will have to figure out engine mounts and oil pan. Don't the front axles bolt to the transmission bellhousing via a bracket on the 4 cyl. models? If so, no need to worry about axle mounts. I remember someone saying that a dealer in Alaska installed a Chevy 350 in a new Eagle back in the day but didn't have any details.

[amosende]

@IowaEagle Thanks for the thumbs up. I'm a newbie to this forum.  Not a newbie to AMC however.
I have my Mom's 71 Javelin AMX. I was in agreement that the A904 is a very solid transmission. I was just
looking for reaffirmation.

@EagleFreak. 

Yeah.  It seems like putting in any Small Block Chevy, would be fairly easy,  if retaining the Automatic transmission. 
IF it isn't broke why fix it? kind of idea.  the v6 4.3 is essentially the 350 just missing 2 cylinders and a balanced
crank.  It seems like every body is going with the 4.0 Jeep engine.  but I feel if I already have the SBC pattern
why not just dump a 4.3 GM in there.  I was hoping somebody was going to tell me, "Yeah, I did it. 100% easy, everything fits
perfectly spacing wise, and the motor mounts are a direct fit." 

I'm pretty heck bent on doing this, so at a Minimum I'll document the entire process for other folk. 

Cheers Mates

[carnuck]

The 4 cyl 904 needs beefing up to go behind a 4.3L if you plan to romp on it even slightly as it's barely strong enough for the TBI 2.5L. First, a wider rear band (sadly there isn't enough room for one from a 999), then a torque converter with an upgraded neck, then a bolt in rear sprague clutch. Extra clutches in the drums help too. It's too bad there weren't any 727s with GM pattern made.

[vangremlin]

Good luck!  This sounds like an interesting swap.  I've been reading up on putting the 4.3 TBI on the AMC 258, and this takes it one step further for the 4 cyl guys.