4g64 swap into my 86 G54 pickup

[Pengineer1]

My 1986 Power Ram pickup runs fine, i rebuilt the motor during our Covid vacation, I put the 38 Weber carb on it and have Hooker super comp headers on it. Yes it's 4wd, 5 speed manual.

I found a pickup cab complete with motor, 5sp 4 wheel drive transmission and driveshafts. It has a 1991 4g64 motor. It was supposedly rebuilt before somebody chopped the bed and frame off to make themselves a trailer.

So please give me all opinions or experiences or advice you may have about me removing my perfectly good 2.6 liter and swapping in this unknown 1991 4G64 .

I'd like you to tell me I'll get better MPG and better horsepower and even better reliability with the fuel injection... but I don't want to assume it hope for that and later find the swap wasn't worth it.

Should I expect that the gearing of my 86 rear axle should match the gearing of the 91? Or should I just swap motors and keep my transmission in place??

Thanks again, guys, in advance. You've always been so helpful through the years and this feels like a big project I might regret?!??
Bill

[Pengineer1]

Is the 4G64 an improvement over the older G54b carburetor motor? Better power? Better gas mileage? Longevity? Even if you may not have personal experience doing this swap I'd appreciate any opinions or ideas. Thanks in advance! Bill

[dash]

if you have a good running 'fresh' 2.6 you're happy with, I'd probably stick with that
Dunno if the old 4x4wireforums still up, but I recall one guy doing a starion 2.6 swap, saying...
he got the 2.6 swap running before adding the turbo, and he preferred that stock 2.6 TBI over his weber carb 2.6 replaced
The MPI 2.4 is a VERY good running simple smooth reliable motor..... sans the common era mitsu(& toyota) ecu capacitor issue
I purchased a $150 Mmax with no gearbox & firewall tear(common at clutch cable pass-thru). Purrs like a kitten. Turbo is the plan
If you had a place to 'store' it and got it for a deal.... I probably would. Also need the 2.4 EFI fuel tank, lines, loom etc
A post or two, here on 2.4MPI replacing old carb motors

[SubGothius]

if you have a good running 'fresh' 2.6 you're happy with, I'd probably stick with that
Dunno if the old 4x4wireforums still up, but I recall one guy doing a starion 2.6 swap, saying...
he got the 2.6 swap running before adding the turbo, and he preferred that stock 2.6 TBI over his weber carb 2.6 replaced...

For that matter, just converting your existing 2.6 to use a Starion/Conquest TBI setup might be worth investigating, since that's pretty much just swapping the intake side of things, rather than an entire engine. Install a jet valve eliminator kit while you're at it.

[FMS88]

Is the 4G64 an improvement over the older G54b carburetor motor? Better power? Better gas mileage? Longevity? Even if you may not have personal experience doing this swap I'd appreciate any opinions or ideas. Thanks in advance! Bill

The stock 4G64 for the trucks has roughly ten more horsepower and very slightly less torque. With your mods to the G54b, there's probably little if any difference in HP. The smaller displacement and FI of the 4G64 should in theory yield slightly better gas mileage, but the difference may not be that great. The 4wd 5spds from 84-91+ all have the same gear ratios, but final drive ratios varied across years and models. A lower rear end ratio improves economy, but results in slower acceleration.
Why was the bed and frame chopped off the '91? Was it in a collision? If someone cut up a serviceable vehicle, I'd be suspicious of the state of the engine or transmission. Very thorough testing seems in order before considering either for a swap.

Found the EPA ratings:
91 4wd w/2.4 19/22 https://afdc.energy.gov/files/pdfs/1991_feg.pdf
86 4wd w/2.6 19/23 https://afdc.energy.gov/files/pdfs/1986_feg.pdf