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1990 GMC Jimmy engine replacement ?

TheRealJimmy

TheRealJimmy

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Bottom end of my engine is knocking. Shop said I need a new long block. So what's my best option? Been looking at the ATK High Performance GM 350 TBI 290 HP Stage 1 Long Block Crate Engines HP31 for 3k. My truck is a stock throttle body engine. Not interested in anything crazy. Just a good driver. What about a 1996 and up Vortec 350? I want to retain my TBI.
 
I am not positive, but I believe that some negative experiences have been discussed in regards to ATK engines.
Hopefully some others can post up more definitely.

You can use a '96 and up Vortec engine, but it will require the adapter intake manifold which isn't cheap, or use an adapter on a carburetor designed intake for Vortec heads.

I have zero experience to tell you if you would need a new chip with this swap, or if it's close enough to work with a stock Vortec camshaft.

@Bent77 knows a good amount of crate engines lately, and also has some experience cams and TBI.
@sweetk30 and @mrk5 also may have some information to share.
 
Howdy neighbor! Winder area here.

I've been slowly planning and looking also. I would like a stockish engine that plays well with TBI also (91 k5). Maybe a small upgrade, because might as well, but less involved than an ls swap.
I have a 97 Yukon and really like the performance/mileage balance. Wondering about a 96 up vortec roller long block with vortec to tbi intake.

Check out Caroline machine engines.
I'll be watching for everyones advice.
 
I bought a performance ATK create engine. 5.3 long block. And it blew up 20 sec after install. Got a new one 2 months later and started knocking within 5 min or running shipped it back and had a bent rod. I WOULD NEVER EVER PURCHASE ANOTHER BLOCK FROM THEM !
 
anything over bone stock gm tbi specs WILL require a custom burnt chip for the tbi .

otherwise the L31 vortec 96-00-03 van will bolt in no problem . just need the intake as said and also a crank position sensor plug to bolt in were the sensor would go .

my k30 budget beater is running a gm long block new L31 and edelbrock pro flo 4 with gm tbi serp belt front drive and stock 87 exhaust manifolds no problems .
 
Can’t you just leave the crank sensor there but leave it unplugged?
 
Concur with above. You will hear people say they added headers or used a slightly larger cam and had no issues, but TBI cannot adjust fueling when the engine is being used hard (or cold engine operation for that matter). It reverts back to programmed values that are quite likely not what the modifications want. Mainly, more fuel.

Vortec is far beyond what TBI ever was, do not even consider the L31 long block unless you are already resigned to burning chips for the ECM (or will go aftermarket for injection control) and have really researched it. Timing and fueling is completely different from TBI. Vortec heads and the roller camshaft make large differences compared to TBI.

I'm running a crate L31 with GM OBD1 that I tuned, I'm not talking about something I'm not fairly familiar with here.
 
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:
 
you ain't wrong. ls swap the world... there is so much aftermarket support for ls a couple of wires and boom it's running. I vote ls
 
I agree with staying away from ATK, why not just repair your engine?
 
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?
 
I agree with all the comments.
I have an l31 in my 85 k20 using summit racing max efi. (was never a tbi rig)
Way better upgrade with the roller cam vs the flat tappet
Only draw back to my rig no OD.
It currently has l31/th400, np208 with 4.10 gears tires are 265/75r16.
It gets the job done.
 
I bought a new complete GM Goodwrench TBI crate engine for my 1991 V3500. I did a small amount of performance increase with a cam. I installed a mild Computer Control cam from Comp Cams. This cam is designed to work with a mild TBI engine without any chip modifications. The cam increased the duration by 30-degrees, and the lift by .20 thousands of an inch. I was able to do a little bit of tuning with my rebuilt and modified TBI unit that has an adjustable fuel pressure regulator, and TunerPro software. By increasing the fuel pressure from a stock 9.5 PSI to 12 PSI I was able to get my engine to have good fuel trim on both the lower 1000 RPM to higher 3500 RPM range. The increase in performance is hardly noticeable, but at least I have new crate engine that runs solid with good compression.
 
Last edited:
dyeager535 said:
Vortec is far beyond what TBI ever was, do not even consider the L31 long block unless you are already resigned to burning chips for the ECM (or will go aftermarket for injection control) and have really researched it. Timing and fueling is completely different from TBI. Vortec heads and the roller camshaft make large differences compared to TBI.

I'm running a crate L31 with GM OBD1 that I tuned, I'm not talking about something I'm not fairly familiar with here.
Click to expand...

TheRealJimmy said:
Crate Engines 19432780
Click to expand...
That's the Vortec engine (late 90's).
  • Horsepower: 255 HP
  • Torque: 330 ft.-lbs.
The TBI engine is 19432778, which would require no programming. For some reason it's more expensive.
  • Horsepower: 210 at 4000 RPM
  • Torque: 300 ft/lbs at 2800 RPM
If I was choosing between the two, I would figure out how to use the roller cam engine. You'll need to learn how to tune and burn chips, find someone familiar who can do it for you (probably via email) or go with another fuel injection method.
 
I would question the shop you are using, the generic needing a new long block leaves a lot open. They should be able to tell you what you need there’s very little chance you need the entire long block assembly unless there’s a hole in the side of the engine. Turn the crank if it’s needed, new bearings, pistons and rings, cam bearings and you are good. Can you get with them to find out the exact problems with it?
 
Blue85 said:
That's the Vortec engine (late 90's).
  • Horsepower: 255 HP
  • Torque: 330 ft.-lbs.
The TBI engine is 19432778, which would require no programming. For some reason it's more expensive.
  • Horsepower: 210 at 4000 RPM
  • Torque: 300 ft/lbs at 2800 RPM
If I was choosing between the two, I would figure out how to use the roller cam engine. You'll need to learn how to tune and burn chips, find someone familiar who can do it for you (probably via email) or go with another fuel injection method.
Click to expand...

Or, for the work, hassle, and expense go LS?

As long as one can "get by" with a used LS, how much of a difference is there in cost? We know the performance is there, but what ancillary costs are there with going LS?

The L31 last I checked was somewhere around $4k, plus needs chip tuning (might as well say $500 there? Random guess), new intake ($200?) new fuel pump ($100 for a quality one?) other stuff I'm probably forgetting. I would assume $1K or so for a good aftermarket injection system if you went that route?

Can a used LS be done for $4800-5300?
 
Budget $3000 for a LS swap using non name brand parts. $100 harness, $75 engine mounts, stock exhaust, $200 for vats unlock and tune. I’m planning this for my ‘91 V2500 Suburban right now and I’m cheap. 5.3,6.0, or 8.1l. Whichever engine comes up first at the best price in the best condition. Around Alabama its $800-1800 for an engine.
 
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