My little brother needed a shop truck. Picked up a 99 Suburban with a 165K and a massive rod knock on friday. Had it towed to the shop and DROVE (remember this its important later!) it into the shop after it was dropped off the wrecker. Had the old L31 out in a little over 2 hours on friday night. Worked all day saturday, but found time in the afternoon to strip the fresh remanufactured vortec heads off the engine in the suburban and tear down the TBI head L31 I had sitting in the garage for a project that we had started that was too far gone to save. The 1991 Formula that had hidden frame damage. I recently acquired a pair of F-car LT1s, one that was disassembled. Pirated the cam for the "new" L31. The L31 long block had come from a machine shop up north and was in a work van. Had blown intake gaskets and coolant contamination. Was already 0.020" over and the lower end bearings still looked great. Cam bearings are not perfect as one had a small gouge in it but not horrible either. Worked most of the day sunday repairing the half dozen failed helicoils we found on the block, got the engine assembled and the 202/207, .447/.459, 116* LSA cam degree'd in 4* advanced on a cloyes 3-way adjustable single roller timing chain and an 2* offset bushing to put it right at 112* ICL. The cloyes sprokets and chain/LT1 cam had 2* advance built in somwhere but thats why you degree cams. Got the timing cover, oil pan, and balancer installed. Pulled the balancer bolt threads out of the crank when the installer tool bottemed out. Either I am hercules or someone used the balancer bolt to install the balancer in its past. Subsequently found 7/16-20 helicoil kits are pretty hard to find on demand. Installed the DCLF S10 converter in the 4L60E and a new input shaft seal. Dropped the engine in the truck monday night, after having to pull the transmission out (flexplate was installed backwards)...As Homer would say "DOPE"! Get it all connected and fill all the fluids. Added all new Delco/Delphi cap, rotor, plug wires, spark plugs, fuel and air filter and replaced a broken knock sensor. Go to start it and VROOM...Blah.....Crank it again VROOOM, Blah....Won't stay running. So I check all the wiring, grounds and sensor connectors. Found one ground slightly loose on the back of the passenger head. Tighten it up. VROOOM, Blah!!! At this point I am PISSED, I knew we had DRIVEN the truck into the shop. Grab a test light and start checking the fuses. All but the dome lamp are good. Grab a multi tester, 5 volt reference is good from the PCM. I knew the cam/crank sensors and basic stuff was working, it would start. I pushed the shrader valve while with a screw driver and had a geyser of fuel. Still seemed like fuel to me. On a whim grabbed a can of carb cleaner, removed the airbox and doused the throttle body while my brother cranked it over. Vroooooooommmmmm and it started to idle. Fuel pump is running. Got out my noid light. It would flash while it was cranking then stop. Right that moment it hits me, the truck has a generic steel key that came with it and its a 99.... VATS!!! So I run across town, grab my tuning laptop and HP Tuners interface to discover I had used all my existing credits. So defeated for the night I go home and buy the credits online. Yesterday morning it was a trip to the Suburban, read the stock calibration, applied the license, and turned the VATS off. Crank, Crank, VROOOOOMMM...And drum roll....It keeps running on its own. Fixed a small vacuum leak by replacing a missing hose that ran to the heater control valve and solenoid and ran it long enough to discover the thermostat was not opening. Ran to Napa and grabbed a 180*F unit. A/C was cool, not cold, so I charged the a/c. I added 10% fuel to the MAF and VE tables to keep it safe and we took it for a drive. Did some datalogging and it was knocking a bit on the 6 month old fuel in the tank. So far very pleased with the truck. Needs the front end rebuilt as the front tires were worn on the inside edges and the busings are pretty bad. The 4L60E looked fairly fresh and the 3.73 G80 rear end is quiet despite the fact the fluid was absolutely disgusting.
Drove it around some last night after getting it buttoned up and worked on the tune a bit. To nobodys suprise, especially mine it is running 90%+ duty cycles with the factory style spider at higher rpm WOT. Saw as much as 92% at 5,500 rpm as it was shifting 1-2.
Tried three different times to get a clean 0-60 video, but was not able to. First time there was a cop camped out in a parking lot ahead. Second time the truck hazed the tires most of the way through first gear and absolutely destroyed them when the power enrichment fuel and timing kicked in at 3,200 rpm, making the suburban drift sideways. If it can light them up like it did on dry pavement, I am scared of what it will do on a rainy day. Too bad the Yokohoma 235/75R15s are almost new because it needs wider rubber on it with a shorter sidewall. The third time traffic prevented me from coming to a complete stop on a flat spot of road. Some other day.
Made a short video for a guy asking how streetable the cam/converter combination was. Being that both are factory GM parts it works very well. Very smooth off-idle and accelerates without excessive rpm or throttle opening. Probably only running 10-15% throttle opening here. If anyone ever gets a chance to tune a GM electronic transmission like a 4L60E or 4L80E, I highly recomeend the BC Trans tool program. Very helpful in getting all the shift tables and TCC tables setup to work with the powerband of a larger cam and higher stall. You can adjust what gears the converter locks in under acceleration, cruise, and WOT. Mine is set for accel lock in 4th, cruise 3rd, and WOT 5th. It will only lock the converter in acceleration in 4th gear. If the shifter is in 3rd for towing it will lock at speed. It will NEVER lock at WOT. Minimum RPM for converter lockup is 1,800 RPM.
http://www.youtube.com/watch?v=3RAqXKq1e9Y
I recorded a video for a guy that wanted to hear what it sounded like at idle. Not overly aggressive but if you know the GMT400 trucks well you can definately tell its not the stock L31 in there.
http://www.youtube.com/watch?v=BG_2awGJz-M
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Originally Posted by 1project2many
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