1994 GMC 2500 5.7l Questions

[rlb]

There are just as many mods for a TBI 350 as a 6.5L. Your limiting factor is going to be the weight of the burb and the 4l60. The 4l60 doesnt like abuse, I've had 2 last to atleast 250K and one truck that ate them every 30-40K including cracking cases. The truck with bad luck was the farm mud truck and had its share of abuse.

Fortunately I discovered the burb has a 4L80. I think it has a factory external cooler too.

I wouldn't mind a little extra power - but first I need to get everything running right and tackle some other problems. I doubt i'll ever get around to it really. Though I wouldn't mind some headers and a new exhaust. Needs shocks, change all the fluids, pitman arm is worn out, U bolts are corroded.

I put in the new OEM single wire temperature sensor last night. The temp is much more steady, only varies 15 degrees max when driving. So the problem is pretty much solved. I'll have to figure out how to calibrate the temperature gauge though (if that is possible). It reads only 160 degrees after a long drive on the highway. IR temp gun is showing 195 at the thermostat and 210 on the cylinder heads.

 

[tanman_2006]

Sounds like your dash gauge is off like just about everyother GMT400.

A better y pipe is good for ~15hp, 2.5" pipe out the manifolds, dual 2.5 into single 3", 3" magnaflow cat (or dual 2.5" cats pre Y), and a good magnaflow or other highflow exhaust. That will free up the back end.

The stock intake baffle on the pass side inner fender barely flows enough air for a 4cyl honda civic. A cheap straight through pipe will help.

After that there are some cheap throttle body mods, msd ignition/cap and rotor, and a chip from TBI chips. Fine tuning like increased fuel regulator pressue might help.

If you start using oil I'd suspect worn valve guides, when you pull the heads you can swap to a vortech head. Vortech heads can add 45hp but you loose torque (high torque came from swirl ports). This will require a new intake manifold, Edelbrock or GMperformance

 

[rlb]

Sounds like your dash gauge is off like just about everyother GMT400.

A better y pipe is good for ~15hp, 2.5" pipe out the manifolds, dual 2.5 into single 3", 3" magnaflow cat (or dual 2.5" cats pre Y), and a good magnaflow or other highflow exhaust. That will free up the back end.

The stock intake baffle on the pass side inner fender barely flows enough air for a 4cyl honda civic. A cheap straight through pipe will help.

After that there are some cheap throttle body mods, msd ignition/cap and rotor, and a chip from TBI chips. Fine tuning like increased fuel regulator pressue might help.

If you start using oil I'd suspect worn valve guides, when you pull the heads you can swap to a vortech head. Vortech heads can add 45hp but you loose torque (high torque came from swirl ports). This will require a new intake manifold, Edelbrock or GMperformance

Thanks, that is good info. I should get as far as working on the intake and exhaust. This motor recently had a head gasket and valve job. It does not burn any oil, but it does have 250,000 miles on the bottom end. If I ever get as far as swapping heads, i'll either do a complete overhaul or start with a crate motor.

 

[tanman_2006]

If the top end is rebuilt then I wouldn't worry about the bottom. Some of them have held together a long time (3-400k) before the truck fell apart around them. Good maintenance and monitoring oil temp, oil press, and coolant temp will get you along way.

Source Unknown