88GMCtruck's 98 Silverado Towpig Build: "Black Fox"

The combination of the tune and the 0411 has really helped the truck out. With the camper I was getting 6.5-7.5 MPG..... This past weekend I ended up getting 9.3 MPG. I about fell over. Mind you this is up a summit and two passes, then back. All at 60-70 MPH.

Did I mention that I can do all 3 of those in overdrive now?!

I was grinning from ear to ear this weekend because of it.
 
My work is never done......

So, I've been chasing down a rough idle in this truck since I bought it. Not quite a miss but it isn't as smooth at idle as it could (should in my opinion) be. I've had a oil leak at the pan for awhile, and it recently started dripping so I decided to replace it and the timing chain while I was in there.

Out goes a few things.
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Once you get here, you have to drop the front diff. Let's just let it be known that a few curse words were said during it's removal and re-install.
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Once it's gone you can have a peek inside.
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The timing set.
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Here is where the second cursing during this project came about. I ordered the GM Performance Parts 502 timing set - the same one I used on the 88, as it's designed for the aluminum timing cover in a gen 6 block. Well, it doesn't work out so well. The Vortec truck has a reluctor ring that fits over the crank gear, which causes it to be thinner. I knew this, but didn't take into account. So a bit of research and I picked up a Cloyes timing set locally for 2x the cost of the GMPP version. To make things worse, Cloyes makes the GMPP version and the only thing different is the thickness of the crank gear.

In order, Stock, GMPP 502 set, Cloyes Vortec 454 Set. The ear pictures show the difference in thicknesses.
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Got all that back together, but while I had the radiator out I cleaned it. You'd be surprised how much junk gets stuck in these. Once it was back in I flushed and re-filled with coolant.
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Since I was in the mode of chasing the rough idle and giving it a tune-up, I decided to eliminate the plastic shafted distributor with a drop in MSD unit. Not only is it pretty, it is all billet and has a much higher quality cap than the OE stuff.
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So, once it was all together I got the timing set within .8 degrees of 0 (tolerance is +/- 2 degrees), did a CASE relearn and still have a rough idle. Not sure where else to look at this point, I've gone through 95% of this thing.......
 
Now, switching away from maintenance, I got around to building a cold air intake. And when I say cold air intake, I mean an actual box that is insulated and sealed from the engine bay...

Started out with cardboard for a template.......
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Then I cut and riveted everything together using aluminum plate and angle. The first stages...
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And here is the finished product.
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The outside is covered in DEI floor and tunnel shield, rated to 1750 F to insulate the box. I decided I wanted a smooth lid so the inside is insulated on it. It's held on with stainless torx screws from a GM squarebody.
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It's a bit of a squeeze, but I managed to get an OEM sized filter in it, plus i'm still able to disconnect and remove the battery with no issues.
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To create a seal and flex joint, I used some sheet rubber and made a retaining ring that holds everything together where the pipe passes through.
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That is all, for now. I plan to clean up the lid some more (brushed or polished, haven't decided) and do a few other things to it, but I'm happy with how it turned out. I'm not really expecting or hoping for any gains, other than the fact that my non-intercooled supercharger will no longer be pulling in hot engine bay air (you know that exhaust manifold is really close to it all).
 
My truck idles slightly rough too even sometimes can have an audible miss. Only at idle tho so I don't worry about it. Probably Chevys lol


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The combination of the tune and the 0411 has really helped the truck out. With the camper I was getting 6.5-7.5 MPG..... This past weekend I ended up getting 9.3 MPG. I about fell over. Mind you this is up a summit and two passes, then back. All at 60-70 MPH.

Did I mention that I can do all 3 of those in overdrive now?!

I was grinning from ear to ear this weekend because of it.

Is this ever unloaded or do you have a daily?
 
Damn dude. I love your posts. Great work.
Nice work man
Thanks

My truck idles slightly rough too even sometimes can have an audible miss. Only at idle tho so I don't worry about it. Probably Chevys lol
What engine though? My truck seems to run rougher than either of my friends 454s.

im going to assume you changed the plug wires right?
Yup, prior to the supercharger install. About 2 years old and 20k miles?

Is this ever unloaded or do you have a daily?
I drive it around on weekends when i'm not camping (I take the camper off frequently), but I still have the 88 and the 02 to drive as well. I'll be selling the 02 shortly. I also have a 15 Toyota Tacoma for work :doublepuke:
 
have you gone through the valve lash?

might have a valve that isnt always closing.
I've considered it may be a valve issue, my father suggested that as well. The Vortec big blocks valve lash is nonadjustable; you just torque the bolt down and it's set.

I think I will be doing a compression test on it soon, it may reveal something more.
 
After updating to my latest tune it has smoothed out some, between that and the ignition upgrade it seems normal now.

Anywho.......

Made a trip to Reno and back the other weekend, here is what my mileage ended up at on the way down. I managed to go over 9 on the way home.
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The other day I finished out the airbox lid, cleaned it up and added a little touch to it.
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Also installed new LED clearance lights and solar on the camper this past weekend.
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Pulled the 88 out to shuffle some things around, figured this was a good opportunity to put them next to eachother. It's amazing they are 10 years apart. Love these trucks.
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Absolutely LOVE the '88.

I really like what you're doing with this truck though, That airbox is nice and clean.
 
i always enjoy seeing your threads being updated.

Whats the specs on he solar for the camper? Thats a good application for it.
Thanks! This is what i'm running plus their PWM controller. Used it this weekend and it seems to keep the battery topped off well enough. http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0H6PVV1RSVQ1ZXPM3GC0

Absolutely LOVE the '88.

I really like what you're doing with this truck though, That airbox is nice and clean.
Thanks!
 
Loaded up the quads and hit the coast.
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On the way back I started getting a squealing sound which got louder and turned into a grinding sound..... Driver's side caliper decided to stick..... quick rest area pull apart and run to town for a new caliper... This is why it pays to travel with friends.
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Made it home. Another issue I haven't touched on yet, as I wasn't sure if it was an issue, as a sound I started hearing in neutral. Kinda a bearing/rattling sound. It started getting louder on my trip to reno, and on this trip it turned into sounds while pulling hills as well... and downshifting. And it started shaking while taking off in 1st...........

All the same symptoms it had a year ago. Almost exactly a year ago. June 10th to be exact, is when I pulled the transmission from the truck.

So out comes the NV4500 fluid draining kit
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Pulled my PTO covers to check the magnet......
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Yup, that is metal. There should not be that much metal in a year/10k miles. After discussing this with a couple shops they are thinking I have a warped bellhousing, causing the alignment issue to eat up the end of the mainshaft. Lucky me, I've found the most cursed NV4500 on the planet.

Hopefully a new bellhousing and this will solve my problem.
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What a bummer dude!!

When my truck went in to have the pump seal done on the trans, they noticed that the opening the input shaft bearing sat in looked odd. So they took ti apart and their best guess was that it never got a final machining done to the bearing channel. Said it was very rough and had course machine marks in it still. they cleaned it all up and put it back together. Said that was the first time they ever had seen that. Who knows what GM was doing with these things
 
Yeah i'm not sure what the problem is, only thing at this point is something nor aligned related to the engine/bellhousing... but i'm not sure that is the case. I'm hoping whatever it is I've replaced at this point.

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Worked on the brakes late last week, ended up doing new Calipers, Rotors, and Ac Delco ceramic pads.
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While I was waiting I got the wheels polished up. Photos don't do it as much justice, but the difference is pretty noticeable
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My buddy also was due for brakes, so he brought his 98 over as well.
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Got the transmission pulled. the input shaft was super loose, ended up popping it out and yup, exact same thing as the last go-round. Main shaft chewed up.
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So, we checked the flywheel/crank for runout, there was none. my flywheel and clutch were perfect, there were still machining marks on them and no hot spots. Used a new oilite bronze pilot bushing, and just to make sure everything was good, a new bellhousing and brand new never ran NV4500.
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So, it's together. New transmission is quiet and shifts tight and smooth. Lets hope this lasts...........
 
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