My K1500 DD Tow Pig

[Supercharged111]

I was pretty far into the build of this truck if you can call it that when I joined this site, so never really bothered to make a thread on it. But the thread on GMTC is gone with the forums, so no good way to keep me motivated on this thing without a thread. Plus it's nice to go back and see that I have made actual progress. So here it is when I first got it in South Dakota, stock as stock can be back in February 2009.

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Strangely it had front frame mounts for a slide in camper and timbren rubbers in the back. The day I drove it home I quickly realized how bad the ABS sucked so I unplugged it and got some TBI lines from the junkyard and deleted the ABS altogether. First power mod I did was add EFILive and suddenly the truck was much more responsive and much less prone to downshifting for nothing. Next up was stealing the headers and modding the exhaust from my crusty old C1500. I drove it up the road to the exhaust shop open header and he extended it and did a great job reusing the stock hangers on my exhaust. From there we moved to CA briefly and that's where I decided the headlights sucked and popped some of these on before towing to CO and back on trip 1 to move all my crap.

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Even with regular bulbs the difference was unbelievable. I can't find any pics from that first trip, but it was pretty hairy with the truck full of car parts pulling a Crown Victoria on my trailer. Truck was already sacked out but didn't have enough tongue weight so it would bob back and forth. That was a long, white knuckle drive. After we finished the move, I did HID lows and my own 4HI mod. Since the tires were shot, I pulled the trigger on some Summit wheels and 285s. At the same time, I swapped in a 7200# GVWR leaf pack (for obvious reasons) and a 1" zero rate add a leaf and cranked the front.

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[Supercharged111]

Not long after that I got deployed, but when I got back I scored a 14BSF with 4.10s and a G80 and matching front diff at the pull and pay. It was the older style though, so I swapped my actuator housing onto that and bolted everything in. That helped recover some lost power of the 285s. I pretty much ignored the truck for over a year after that because I bought a Z06 and started tracking it and DDing it because it usually never gets less than 20mpg. When my first daughter was born though, the truck developed a TCC shudder so I decided to do a custom HD2 shift kit along with PWM delete and a full flush.

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Servo shaft was pretty hammered, I just blended it with a Dremel and it came out OK. Did the Corvette servo too.

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The truck would snap your neck on a WOT upshift after this, and I later found out why that was.

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I was running a speed density tune on the blackbox at the time which puts the trans up at full line pressure all the time. I was on my way to pick up my Camaro that I'd just bought pulling my empty trailer through town in 3rd gear. After I crested the hill up in Monument which is around 7000' I reached for OD and nothing happened. I was certain at that point that I was about to tow home with only 1st and 3rd, but luckily that was not the case. The 2-3 shifts were weird, but I still had the first 3 gears so I loaded up and brought it home.

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[Supercharged111]

By now you might have guessed that this was where I performed the 4L80 swap. I went to the pull and pay and all they had was a 97 2wd trans with no pan so I snagged it anyway. Since it was going to be rebuilt, it wasn't the end of the world to hunt down and output shaft and extension housing. I'm lucky enough to have a neighbor who owns a trans shop, so I did the swap there.

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It took about a week to swap it, change the tune, and have it driving again. I had to convert the t-case input to 32 spline as well so while I was in there I replaced some shift fork pads and added a c clip eliminator of some kind. Also had to have the driveshaft shortened out back and I ghetto extended the front. Truck was way gutless after the swap in 1st and 2nd, turns out when I did the trans segment swap the engine segment somehow reverted to stock. I got that fixed and it was while I was tuning the 4L80 that I discovered the whole MAF unplugged causing max line pressure. The 4L80 was downright uncomfortable at max line pressure. I also didn't have the case lower housing at first and noticed a vibration at WOT around 3000 RPM. A later score at the junkyard fixed that along with the bars that bolt to the motor mounts. The trans came at a good time because the following year I'd had enough of my POS open deck trailer and went enclosed. This would have surely finished off the 4L60.

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This also drove the need for the pictured tow mirrors and the Tekonsha P3 as my old controller just wasn't stopping this new trailer. You can see the Esky cluster and LEDs here too.

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Next thing I did was finally get off my ass and do the 411 swap.

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The truck was immediately better and my phantom knock was gone so the truck ate a bunch more timing and ran a lot snappier. You can see my sweet storage box here too, love that thing. I keep a quart of ATF and oil along with a rag and funnel in there.

 

[Supercharged111]

Next I began to chase a misfire that was gradually getting worse. Idle was sometimes a little unsmooth and I began to get a flashing MIL at WOT. Since I'd already done plugs and wires recentlyish, I went for cap, rotor, and distributor gear. Cap and rotor were bad, but really didn't look trashed. Distributor gear was razor thin and turned out being the reason I could never get my CMPRET any better than 29 degrees off.

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This did nothing for my misfire, so my next move was going to be new plugs and some roller rockers for a little more torque. Well the pushrods rubbed the head, so I had to yank the heads to drill them out. While I was at it, I decided to add a marine cam, new timing chain/gears, and new main/rod bearings. Truck had about 230k on it at the time, sure doesn't look like it now though.

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Here you can see the trimming I did on the trusses in the valve cover to clear the wide body rockers.

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The lifters and intake valley were pretty nasty, PO must have sucked at oil changes.

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I bought the truck with 15X,*** on it. I put Berryman's parts cleaner in a Harbor Freight ultrasonic cleaner and it was magic. Unfortunately, it wasn't able to clean inside the lifters very well and I found when I went to set lifter preload that some of the plungers wouldn't depress at all. There were a few I had to figure out how to disassemble further than what is pictured and they were full of gunk. I regret now being too lazy then to take them all apart, I can't help but wonder if that's the cause of my misfire. After I got the truck back together, the misfire was much worse. I began to suspect the spider at that point as I hammered it pretty good with carb cleaner when it was out of the truck. I thought maybe it melted the plastic a little where the pintles are. The more I drove it, it did get better though so now I wonder if it's not the pitted exhaust seats I ignored when I had it apart and perhaps they filled back in with carbon which helps it seal better? Despite all of that, I went after the tune to work on the low RPM torque and was able to exceed low end before the cam and rockers and top end was also noticeably improved. My cold start lifter tick was now gone too.

 

[Supercharged111]

This was as clean as the intake would come, and it sat in the hot tank for a long damn time. I also disabled the EGR before 160,000 miles and had sprayed a bunch of carb cleaner down the intake in the past but it seems to have a good amount of blowby. Burns about 2 quarts every 5000 miles.

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Cam came in right at 106.5 degrees, so no need to adjust it even though I got the Cloyes adjustable timing set. Best part about it was that it was a large single roller, unlike the stock link setup or the POS bike chain they used on the 4.3.

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Here's how nasty the valley was. I've always run Mobil 1 synthetic in it. I'm pointing out the lifter spider boss to my friend whose TBI truck we later converted to roller.

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And here's a problematic lifter, I had a few of these. You can see that the plunger didn't return to the top.

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[Supercharged111]

This was definitely one of the more time consuming projects I took on, and I did it at a terrible time: February. I had to squeeze my ass through this tiny hole to get under the hood to work which added considerable time and asspain to the whole ordeal.

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Once this was all done I was good to go until May when I killed the battery so on the charger went and when I fired the truck up the fan snagged it and destroyed the charger and the fan assembly so it was finally time to do the Mark VIII fan swap I'd been procrastinating for years. I was able to make it very simple and effective with some angle aluminum from Lowes.

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Later I built a plate to seal the core support to the radiator.

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Those 2 30A relays wired in parallel didn't work all that well and one of them got cooked, so I replaced it then and later went to something a bit bigger.

Somewhere in there I managed to install an OHC with DIC.

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Since the 411 swap it seems to read about 1mpg optimistic. I think it's the MAF calibration.

 

[Supercharged111]

Well you can't own a truck for so long and not make it worse too. I had an LT1 on an engine stand in the back of the truck and didn't do a very good job tying it down. I dumped over and snagged on the bed rail so the motor didn't hit the ground but it royallly ****** the side over. The pic doesn't do it much justice.

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So $1,000 later I had the whole bed repainted and it looked better than ever. A friend of mine knew a guy who does bodywork by day and started working on the side for some extra cash. I had to leave town a few times that year for work so I just left it at his place so he could work at his own pace. Next was tires again, the last set of Duratracs went 44,000 miles so I guess I got my money's worth seeing how they're only warrantied to 40k.

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Yeah, it was time. My cousin got 80k from a set back in MI, but the roads there seem a lot less abrasive than here. Plus I take corners here at what passes for highway speed there. I also went with 17" rims this time instead of 16s. I immediately kicked myself because I thought 20" tires would be hella expensive but it turns out they're so common that they would have been even cheaper than the 17" tires. FML. Same style rims though.

Next up I got real sick and tired of retorquing exhaust flanges every couple of months, so I welded them right to the headers so they'd quit hogging themselves out. I hate the sound of an exhaust leak.

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Yet another mod I took forever to get around to was the GMT800 MC. The truck definitely stops better, but IMO the only reason for that is because the larger piston's single bore reduces pedal travel which means you get more squeeze on the brakes before the pedal over centers and becomes worthless. At best, it's less bad even with rears properly adjusted. Hydroboost is on the short list of things to do. I'm one of those **** ******* who purges brake fluid once a year.

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Next up I scored a decent captain's chair at the pull and pay to replace my 60/40. By this time I also had the dually and decided I liked the center console setup. It also leaves more room for tiny back seat occupants and their respective seats.

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[Supercharged111]

Compare that to what I pulled out.

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I'd love to have one as fresh as what's in my dually, the bolster is still fluffy on it.

So now that brings us up to another fairly significant mod: the marine intake and blower. I love how factory the whole setup looks, but it would be nice if the compressor was larger than 1.6L as it only makes around 4psi here in CO pullied down one from stock.

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The intake itself is the easy part, it bolts right on. Kicking myself again now that I forgot to rip all the lifters out, apart, and clean them to eliminate that as a possibility of my misfire. Part of why I didn't was because I was so certain it was the spider causing the problem. Well now that the intake is on, gotta start dealing with what makes this swap an actual thing. I started with fuel. I was at Whisler Bearing getting a bearing and on my way out of their drive I saw an Aeroquip sign so I pulled back in and got what I needed.

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All that for a couple of 4" long pieces, plus the other adapters for the rail itself. It was a tight fit with the plug wires. I'm lucky the CMPRET is good with the distributor where it sits.

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Here's what I came up with for the MAP sensor. I had to stack an o ring onto the MAP sensor as well as the hole is a little big. I suppose I could just drill and tap the hole, thread in a barbed fitting, and connect it to the MAP sensor with a piece of hose but this hasn't given me any problems yet so it can stay. Off to the right you can see the silver aluminum adapter that bridges the gap between GM fuel rail and -6AN.

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[Supercharged111]

I had to deal with a vacuum source now for the brake booster too since the vacuum setup is a bit different on the marine intake. The reason for the MAP sensor mounting is because the boats used an integrated MAP/IAT. I totally would have run one, except I went with a 2 bar MAP sensor so I could read boost. I just got a 2 foot chunk of hose and went to town, wrapped it where it goes over the exhaust.

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And then there's this 1 big port that was pretty useful, I added a 90 to get it all to fit nice.

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Now I'm not much of a fan of this cutout, it's way bigger than it needs to be. Unless HB interferes more with it? Either way looks like a huge restriction.

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From here I really just had to peel back the convoluted tubing on the factory harness to rerun the IAC, TPS, and IAT pigtails. Miraculously they were long enough to make their new journeys so no chopping there. I did have to solder in 8 injector pigtails though but I was expecting that.

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And then there was boost! I first tried running the purge solenoid into the charge hat but because that area saw boost I got codes and it wasn't happy. You can see the blue vacuum line in the background, I was experimenting with what sort of vacuum signal to feed the bypass valve. I ended up giving it vacuum only because Jon Bond freaked out when I mentioned using boost to help hold it shut. I recently had the blower off to replace the PS pump AGAIN and drilled/tapped a hole to give the purge solenoid its own dedicated vacuum only source and now that code is gone.

 

[Supercharged111]

It probably goes without saying that this was a used blower kit that I bought. I was only missing 2 small metal spacers and something to make my throttle cable bracket work properly. I found a way to get it better than just single shear with this small piece of flat steel.

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Then there was the matter of 3psi not gonna cut it for me, so I replaced the 3" pulley with a 2.75" pulley and got all the way to a whopping 4psi. Well at least it's sea level fast now. And Gatorback belts FTW, no squeaking here.

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This orifice also perplexes me. Seems any restriction to the outlet of a supercharger would drive IATs up.

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Definitely some room for improvement with this kit. I also decided to replace my then hollow Magnaflow with a not hollow Magnaflow (that was 4" longer too) and also got a resonator tip. It only made it slightly less loud, but at least it sounded less blatty than a straight pipe.

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I decided to go overkill and replace the 2 30A relays with a starter solenoid, but it died a quick death for reasons unknown.

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Perhaps it doesn't like being on all the time? Whatever, it was loud and annoying anyway. I have no pics of the new setup yet, but it's a 50A Hella relay and a 50A resettable breaker with a freer flowing power source. Truck finally blows ice cubes at an idle.