98 vortec l31 build

[Abuentipo]

I just acquired a 98 350 motor to swap out my 305 in my 97 c1500. I don't know much about the motor except that vehicle that it was in was in a rollover and it has 160xxx miles on it. I am in California and am restricted by emmisions b.s. I dont want to have any future issue with the motor so I plan to send it to the machine shop and have them rebuild it in the next few days. I was quoted $2500-$3000. *ouch* . What upgrades can I do while I am tearing down the motor that will not affect the computer and will still pass smog?

I was thinking 20 to 30 over new pistions rings bearings freeze plugs and upgrade to bigger timing chain and bigger oil pump. Any other suggestions? Where can i find parts to save me some $$$$ from the shop ordering?

 

[98 Nitro]

Check compression, if it's good save your money and run it. A brand new L31 from GM is only $2000 so I would not rebuild.
As for performance parts you could put in a mild camshaft and do a spring upgrade the smog guys won't know unless you tell them.

 

[Abuentipo]

Check compression, if it's good save your money and run it. A brand new L31 from GM is only $2000 so I would not rebuild.
As for performance parts you could put in a mild camshaft and do a spring upgrade the smog guys won't know unless you tell them.

What about computer issues with a cam? What's not going to compromise that but give me a nice punch

 

[884x4310ci]

Keep the cam on the smaller side around 220 duration to keep the ecu happy.

 

[97K1500Silverado]

I blackbear tuned my 97 k1500 with 5.7 L31. This made the biggest seat of the pants difference. The engine now revs out more, less delay when pressing the go pedal, trans shifts are firm and quick when on the gas but still smooth when half throttle or less.

Biggest part of tune is them removing torque management. They also increase trans line pressure when stomping on the accelerator and quicken the shifts.

My engine and trans are all stock with 208k except for the following:

Shorty headers with egr hookup
Flow master head pipe kit with larger diameter head pipes, mandrel bends, and high flow cats. Then a true dual exhaust from cat back.

All new 02 sensors. Blackbear can tune out the 2 after the cats but I left them in so I know if a cat get plugged, etc.

 

[df2x4]

Biggest part of tune is them removing torque management.

It makes a big difference in the way things feel for sure, however if your truck is equipped with a 4L60E then I would strongly recommend leaving the factory torque management alone. I'm convinced that it's one of the only things that keeps those transmissions alive.

I had Black Bear remove 100% of torque management from the tune on my red '97 with the V6 back when it still had a 4L60E, and it smoked my 130K factory transmission in about 500 miles. Had it rebuilt by a very reputable local builder to the tune of $2700 or so with several major upgrades. That one lived about 10K miles, but I think the only reason why was because I had Black Bear put all the torque management back into the tune about halfway through it's life.

Speaking from experience torque management is a very good thing, at least for the 60Es.

 

[97K1500Silverado]

It makes a big difference in the way things feel for sure, however if your truck is equipped with a 4L60E then I would strongly recommend leaving the factory torque management alone. I'm convinced that it's one of the only things that keeps those transmissions alive.

I had Black Bear remove 100% of torque management from the tune on my red '97 with the V6 back when it still had a 4L60E, and it smoked my 130K factory transmission in about 500 miles. Had it rebuilt by a very reputable local builder to the tune of $2700 or so with several major upgrades. That one lived about 10K miles, but I think the only reason why was because I had Black Bear put all the torque management back into the tune about halfway through it's life.

Speaking from experience torque management is a very good thing, at least for the 60Es.

I’ve towed 3500 lbs with the tune for 5k of the last 30k miles. Trans is still going strong.

I did install a trans temp gauge to monitor temps. My truck has tow package with f44 semi float rearend, trans cooler and oversized radiator. Trans temps unloaded hon highway are 170 in 95 degree heat. Towing 3500lbs in mountains trans runs 195 - 220. Hottest I’ve seen was 235 which I pulled over and let it idle and cool. This was when towing up a long uphill dirt road at 10 mph.

I did a Home trans flush and replaced all fluid with valvoline max life full synthetic. At 170k miles.

I had the TCC lockup check engine code p1870 and replaced the TCC lockup valve with an oversized valve (teckpak).

You can roast a 4l60e quick if you don’t fix the p1870 code. The TCC lockup valve gets stuck in its bore and the torque converter won’t lock which creates a lot of heat = trans death.

Your choices then are new valve body, or try oversized TCC valve.

 

[Abuentipo]

I do have the 4l60e. I had to rebuild it about 20000 miles ago. I had them install the stage 2 rebuild kit. Should handle almost anything I do to the motor now. I do have an 4l80e 4wd that came with the parts truck I bought I can always convert it If needed be.

 

[df2x4]

My PCM was not throwing any codes, and my transmissions were always maintained properly. Cooling was more than adequate. They still didn't live long.

By all means do what you want with your truck. My experiences were certainly out of the ordinary, but I feel obligated to bring them up and warn others. IMO messing with torque management on a 60E is not a smart thing to do if reliability is a concern.

The Black Bear Performance tune is a great upgrade, though.

 

[east302]

Consider swapping out the stock injectors for the multiport version. It’ll all be apart anyways so you might as well. It definitely helps throttle response and is about a $300 part (if I remember right).


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