What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

1990 GMC Jimmy engine replacement ?

sweetk30 said:
I might catch crap for this but if i was to swap again ....... LS would be my flavor .

All the work / time / parts for sbc & aftermarket efi i could of done LS 5.3 and been better than my L31 & pro flo 4 and better mpg also . Plus i could of done a 4L80-e swap and got od and controlled by same pcm .

I am currently selling my sbc extras . Bbc stuff . And doing 8.1L vortec or 5.3LS stuff anymore . In my eye mpg / power / price point / engine AND trans control in 1pcm = WIN :saweet:
Click to expand...
1710431833379.png
 
How many miles are on the truck?
any chance you could just do a crank kit and keep rolling?
I agree... any engine upgrades on a TBI engine are a waste..... UNLESS you have a computer that can be re-programmed, or a modified Chip! I got a chip for the dually (custom burn) to increase the power at RPM when I was towing a lot. the only mod really was exhaust, but what a difference.
 
A major question here is whether @TheRealJimmy is doing the work or paying a shop. You won't get a budget LS swap having a shop track down all the bits and pieces and figure out how to make it work. Likewise, if they R&R the engine, that might cost as much as a longblock.

But if you are doing your own work, you can still get an SBC crank for $200-some and other parts are cheap as well. That would get it up and running for the lowest cost and no tuning/chips/harness mods/gremlins. Of course if it needs rings/bore/everything, a crate engine might still make sense.

Also, why not look around for a used engine?
 
While an LS swap is probably the best bang for the buck performance wise, it is not what I consider cheap. Thats a wholesale change from a Tbi. Harness, mounts, exhaust plus all the needed accessories to fit the engine. Unless you source most of it from a wrecked truck you are going to be investing a lot.

My 5.3 was essentially a free long block without intake, accessories or exhaust manifolds. I had easily $2500 in buying the rest of the stuff I needed.

So yes a LS swap is better in every way, but isn’t cheap. The cheapest route if the budget requires it is to get a Tbi 350 good used or quality reman and go. I wouldn’t fuss with trying to deal with even a mild cam and more efficient L31 with the limitation of tuning on the Tbi system. If you went with a L31 I’d pitch the TBI for a more modern aftermarket EFI system of your choice. Yes, more money but you won’t spin your wheels screwing with antiquated tuning technology burning proms and still not run perfectly.
 
TheRealJimmy said:
So I could just buy the Chevrolet Performance L31 350 C.I.D. Base Long Block Crate Engines 19432780 and add the aftermarket TBI intake and be good? No ECM reprogramming or anything else?
Click to expand...
If its rated for a match to the old tbi or comes with a chip .
 
do it jewish GIF
IMG_20220725_081504_227.jpg
 
Blue85 said:
A major question here is whether @TheRealJimmy is doing the work or paying a shop. You won't get a budget LS swap having a shop track down all the bits and pieces and figure out how to make it work. Likewise, if they R&R the engine, that might cost as much as a longblock.

But if you are doing your own work, you can still get an SBC crank for $200-some and other parts are cheap as well. That would get it up and running for the lowest cost and no tuning/chips/harness mods/gremlins. Of course if it needs rings/bore/everything, a crate engine might still make sense.

Also, why not look around for a used engine?
Click to expand...
I'm having a shop do it.
 
TheRealJimmy said:
Might just buy a 1996 and up 5.7L vortex from GM performance and get a TBI intake for the vortex heads
Click to expand...
vortec ........ and thats a lot of money for the L31 these days . i got lucky and got mine just before the big jump at $1,850 delivered . and like we said you will still need the chip made for it .

also you need to do a coolant bypass hose like a big block chevy has with a 96-up vortec sbc with the older 95 down water pumps . there is no bypass hole in the block as gm moved it to the water pump and intake . i was chasing a surging temp and coolant smell till a gm warranty tech guy told me about that and solved the problem .
 
sweetk30 said:
vortec ........ and thats a lot of money for the L31 these days . i got lucky and got mine just before the big jump at $1,850 delivered . and like we said you will still need the chip made for it .

also you need to do a coolant bypass hose like a big block chevy has with a 96-up vortec sbc with the older 95 down water pumps . there is no bypass hole in the block as gm moved it to the water pump and intake . i was chasing a surging temp and coolant smell till a gm warranty tech guy told me about that and solved the problem .
Click to expand...
The GM performance vortec engine all come with the hole drill in the block now, just like the older engines did.
 
TheRealJimmy said:
So I could just buy the Chevrolet Performance L31 350 C.I.D. Base Long Block Crate Engines 19432780 and add the aftermarket TBI intake and be good? No ECM reprogramming or anything else?
Click to expand...
With no performance mods, that'd be a relatively cheap way out. Though if you have to spend $3k (ouch) for a long block, I'm in agreement with the LS swap.
 
Holey76 said:
With no performance mods, that'd be a relatively cheap way out. Though if you have to spend $3k (ouch) for a long block, I'm in agreement with the LS swap.
Click to expand...
Paying a shop to replace a small block is one thing. Paying a shop to perform a LS swap is going to be at a premium for parts and the labor.
 
You are asking for trouble just doing a short block. TBI heads are junk after 200,000 miles. Using those old heads on a new short block will make you have to do the job twice after those heads go to sh!t in short order. TBI blocks are good rebuilders, but the the heads are trash after 200,000 miles from old age metal fatigue. They will crack, and are not worth the money to rebuild. The only way to do this job once is to buy a whole new engine, or rebuild the block, and get a set of aftermarket heads for it.
 
TheRealJimmy said:
I'm having a shop do it.
Click to expand...
If you have to rely on a shop to do this kind of work, you may not be in a position in life to own classic vehicles. Unless you are made of money, in order to have a quality restoration shop do all this work for you owning a classic vehicle may not be for you. Most of the people on this web site have some type of facility, garage, tools, and skill set to take on this type of job themselves. This insures the job is done right, and not a hack job done by a shop that does not give a sh!t about your classic vehicle.
 
You must log in or register to reply here.

Latest Posts

Top Bottom