Small block 4 speed to big block 4 speed swap

[Corey383]

I have recently picked up a 1986 W250 Long bed with a tired 318. I want to know what all has to be changed with the 4 speed tranny. Are all big block bell housings going to work? Will the 383 clear the brake booster or is it the 440 only that has this issue. It’s mostly the tranny that I have questions about.

 

[65 sporty]

Which 4 speed? Read the reply in this thread

1972 D300 1-ton 440/727 > want to swap 727 to 4-speed

 

[7mopar]

Brake booster will make a difference also.

 

[Corey383]

Thanks guys. I’ve just got the truck up here from Tennessee and had to put it to work right away. It has more pressing issues, but will definitely need to upgrade the power plant soon. I’m just trying to decide if I need a 360 or 383.

 

[7mopar]

360 will have more parts available. I myself an partial to the 383. Only money would keep me for the change but the 360 would be definitely cheaper to build in the future. If a fuel system upgrade doesn't help the 360 it just might end up a 410 but it's only got a little over 100,000 on it. Long time from needing a rebuild.

 

[paul massaro]

my 75 ramcharger had a 440 with pb ps air , was no fun to work on but it cleared the pb assembly . it's long gone without any under the hood pics . but does your booster look like this one on my 74 d200 with a 360 .

 

[Corey383]

I know the 440 (RB) will definitely need the brake booster relocation kit if it was a small block truck, but was not sure if the 383 (B) would be able to clear. I was probably going with a 2” body lift to clear 33” anyway, so this would help also.

 

[7mopar]

There is not that great a difference between the two. There were smaller booster even in the 80's.

 

[Craig Burriss]

There’s a 8” booster that was on some of the heavy duty trucks that will clear the 440 with no issues. I believe the parts stores refer to it as the “dual diaphragm” booster. If you use a body lift, the factory 11” booster will clear as well. Or you could do what I did and just delete the booster.
83 RamCharger with a 440

 

[Cranky1]

The 383 has a lower deck height than the RB engines so it may clear....can't remember off hand how much lower the DH is on the 383 but it's easy to find out. Staying with a small block would make things easier but the oil pan from the teen will not fit the 360. Also, the teen is internal balanced while the 360 is external balance so a different flywheel will be needed but there use to be a template kit that could be placed on the internal balance FW showing where and what size drills to use to make the IB FW work with the 360. Not sure if that's even available either anymore. One more item....motor mount brackets from the teen have a bit different spacing on the driver's sid but that can be fixed using washers.