What did you do to your NBS GMT800 Tahoe/Yukon Today?

Rocket Man

Mark
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So, I always wanted to build up an engine and I'm not getting any younger. Quite the opposite. I just purchased a 6.0L block. Impulse buy - maybe. But, I should have dropped a 6.0L in it when I replaced the engine 15 months ago. Luckily my wife supports the impulse.
I have been wanting to build one myself for awhile. I’ve been thinking about one for my 08 Silverado, maybe a 6.2. It’s got a 4.8 in it now that’s tuned. The truck only has 60k on it, doesn’t get driven much at all. It would be a cool project. Looking forward to your build. Gonna start a build thread for the motor?
 

RAMurphy

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I have been wanting to build one myself for awhile. I’ve been thinking about one for my 08 Silverado, maybe a 6.2. It’s got a 4.8 in it now that’s tuned. The truck only has 60k on it, doesn’t get driven much at all. It would be a cool project. Looking forward to your build. Gonna start a build thread for the motor?
Not really confident on how to do that, but will most definitely try to make that happen.
 

iamdub

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I have been wanting to build one myself for awhile. I’ve been thinking about one for my 08 Silverado, maybe a 6.2. It’s got a 4.8 in it now that’s tuned. The truck only has 60k on it, doesn’t get driven much at all. It would be a cool project. Looking forward to your build. Gonna start a build thread for the motor?

If it were up to me, I'd do a stroked smaller bore block- make a 383 (6.3). More cubes than a 6.2, but more streetable TQ from the stroke. There are other benefits, but it should be more efficient as a street truck engine than what a 6.2 could be, and without high compression so it can happily run on cat piss. Can get a stroker assembly kit (crank, forged rods and pistons, rings, etc.) for ~$1,500 and 4.8/5.3 blocks are a dime a dozen. The lower RPM power but still with wide power band would complement a 4-speed trans.
 

iamdub

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Not really confident on how to do that, but will most definitely try to make that happen.

I second a build thread. Go here: https://www.tahoeyukonforum.com/forums/under-construction.76/

At the far right click the yellow box that says "Post thread" and fill in the boxes as usual.

*EDIT* I just saw you already know how to make a new thread. At least, you did back in July when you had a fuel pump question: https://www.tahoeyukonforum.com/threads/fuel-pump-question.135555/. I guess you just needed to know where to post such a thread.
 

Rocket Man

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If it were up to me, I'd do a stroked smaller bore block- make a 383 (6.3). More cubes than a 6.2, but more streetable TQ from the stroke. There are other benefits, but it should be more efficient as a street truck engine than what a 6.2 could be, and without high compression so it can happily run on cat piss. Can get a stroker assembly kit (crank, forged rods and pistons, rings, etc.) for ~$1,500 and 4.8/5.3 blocks are a dime a dozen. The lower RPM power but still with wide power band would complement a 4-speed trans.
I will have to look into that. I know none of the 4.8’s have DOD/ AFM either, do any of the 5.3’s?
 

Walchit

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I will have to look into that. I know none of the 4.8’s have DOD/ AFM either, do any of the 5.3’s?
I think the gmt 900 5.3s have dod. At least the one in my buddy's yukon has the dod valley cover. But the guy he bought it from said that it was a hybrid, and that they "Ls swapped it" lol. So I'm not positive
 

Walchit

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Was gonna leave these pieces that I missed unpainted, but I gobbed some primer on. Now I'm waiting for paint to dry, lol

Oh, and I got the BTR 11/32nds 7.375 pushrods in, if my measurements are correct it should have me at .075 preload on the lifters. Hopefully I have a nice quiet valvetrain, or I'm probably gonna freak out, lol
 

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iamdub

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I will have to look into that. I know none of the 4.8’s have DOD/ AFM either, do any of the 5.3’s?

For the Gen4 engines, all the 5.3s have it. The Gen4 4.8 and 5.3 blocks are all the same. The 4.8 has the AFM towers cast into it, but they're capped off with the valley cover. What makes a 5.3 out of a 4.8 is a different crankshaft (for longer stroke) and different pistons (4.8 has flat tops). So, you could pick up a Gen4 engine off Marketplace for a few hundred bucks, drop it off at the machine shop to be bored and new bearings installed, then put it together with your stroker kit. Have the stock 799/243 heads cleaned and mildly worked or CNC'ed or buy aftermarket heads. Maybe $3,000 and you'll have a 383 that'll out-pull a 376 in the usable range while meeting or exceeding its efficiency, depending on your cam, head and CR choices.
 

iamdub

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Was gonna leave these pieces that I missed unpainted, but I gobbed some primer on. Now I'm waiting for paint to dry, lol

Oh, and I got the BTR 11/32nds 7.375 pushrods in, if my measurements are correct it should have me at .075 preload on the lifters. Hopefully I have a nice quiet valvetrain, or I'm probably gonna freak out, lol

Just to be that guy, the only way to know is to measure with a length checker. I did all kinds of double-and triple-measuring during my build. ~15K miles later, when I had it apart to replace the rockers, I checked ALL of 'em. They were all over the place with the corners being the highest difference. This coincides with the corner cylinders having higher piston heights. After some research, I learned that, apparently, LS engines can be slightly "curved". Since the LS7 lifters are happy within a relatively wide range of preload, I decided to not order a specific length for each one and just split the differences to lower the highest preloads and raise the lowest preloads to have a much more balanced average that was much better within the acceptable operating range. Tedious work! I have the rods in hand but haven't had a chance to install them. I'll have three different sizes altogether, so not too bad.
 

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