New hemi/old tranny?

[Car #4]

Can you swap a 5.7 into a truck and still use the 727 transmission?

 

[ruffcut]

The short answer is YES!

 

[Car #4]

Thanks. I expect I would “need a little help from an a-daptor kit”.

 

[70chall440]

I don't think you need much, perhaps a flex plate as a SB 727 will bolt up to a G3 Hemi.

 

[Car #4]

I would do need an electronic control module for the engine wouldn’t I? Or can you hook those motors up old school?

 

[Jerry Hall]

Small block 727 will work as is with a 1" spacer (adapter plate).
Gen III engines can be converted to old school, but why? You lose so much by converting to carburetor. I ran my 5.7 with a carburetor for a while, 15mpg, then went back to stock fuel injection, 25+mpg.

 

[Car #4]

Small block 727 will work as is with a 1" spacer (adapter plate).
Gen III engines can be converted to old school, but why? You lose so much by converting to carburetor. I ran my 5.7 with a carburetor for a while, 15mpg, then went back to stock fuel injection, 25+mpg.

I didn't mean going back to a carb. I just meant for spark control and timing, etc. I'm just trying to learn here what all would be involved in making that switch. The truck has a big block 727 in it now. It's 4WD so there's there's a transfer case hanging on the side of it. I would just do an engine swap, that's all, if I even do that.

 

[ruffcut]

I didn't do the swap but my brother did in his sons duster. You will need a small block trans. You will need a controller for ignition and timing etc. You really should watch some videos on the subject to gain some insight as to what is needed. Depending on what the gen 3 came from. you may need an oil pan then theres the exhaust manifolds or headers and an in tank fuel pump or some other arrangement for more fuel pressure if going efi. Lots to sort out. Even if you have a good running gen 3, it will be alot of ground to cover. Good luck, and let us here know the swap goes.

 

[Jerry Hall]

Big block 727 won't work, unless someone has made something lately. My 66 Satellite was built before much was available. I had to build my own motor mounts, oil pan, and had a small block 727 built to hold up to 600 plus hp. I used a crate 6.1 and factory computer with a modified stock wiring harness.

 

[392heminut]

Small block 727 will work as is with a 1" spacer (adapter plate).

I don't think so. I bolted my small block 727 directly to my 5.7 Hemi. I used the flexplate that was on it also (2004 truck motor). I just had to have the welds holding the starter ring gear cut and the ring gear removed. I've been driving it like that for 17 years now.

The old Chrysler 392 and 354 hemis needed a 1" spacer plate though. I ran a 57 Chrysler 392 in my Cuda before the 5.7 swap.

 

[67Charger]

100% compatible SB 727 or 904 directly to the G3 Hemi block with the offset "adapter" flexplate. no extra spacers needed anywhere. Will still use old style starter too.

 

[70chall440]

You can control the engine is a number of ways;
- you can use a stock harness but it has to be modified and the ECU flashed
- use a stock harness and an AM controller (ECU)
- complete AM harness and ECU (think Holley Terminator X max)

 

[67Charger]

Engine control with Holley terminator was SUPER easy. Plug-n-play with the factory parts in place of the OEM harness. Canned tune was good enough to start and took very little to get it running great. IAC needed to be re-pinned to use an LS throttle body. Fuel map was wonky, but very easy to adjust intuitively, and the spark table was VERY retarded, but simple to adjust. Acceleration enrichment was 5x too much and would about kill the car on tip-in, but once leaned out is is VERY snappy. 100% recommend.