1999 K2500 Suburban 7.4L

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Papablunt

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So what's in the box?
Gibson ceramic coated shorty headers, GP113SC.

I've been wanting to do headers for awhile. I soaked everything in PB blaster for a couple days before I started. I was able to remove all bolts and studs without breaking anything, but... I already had two broken studs. Of course they are recessed 1/4" in the block. :) The driver side exhaust gasket was blown through in every cylinder. The condition of the cylinder 1 mating surface clearly shows this should have been done along time ago! You can actually see the exhaust manifold is peeled off the head (outside of cylinder 1) in the first picture below.

Since I'm retaining the EGR, and the EGR tube is priced like gold now ($400+ on eBay), I didn't have the option of cutting the tube for easy manifold removal. The top EGR tube connection was simple enough, but the EGR connection on the manifold wasn't happening with the manifold on the engine. I ended up snaking out the manifold w/ EGR tube in place, and it came out just fine after a few minutes. Damn good thing, because it took the power of Thor to remove the EGR nut on the manifold. I was hitting the wrench as hard as I could with a 3lb sledge, and it took a solid 8-10 whacks before it finally freed. Even then, it barely turned without a lot of force, so trying to get that thing off with the minimal space in the engine bay would have filled up my swear jar.

I'm waiting for some free time to finish up the install. I still need to remove the two broken studs, mount headers, cut and fit the new exhaust pipes to the original piping, and get it welded up soon after.. A new muffler is in my future, but haven't really decided what to go with. I'll likely go with the school bus muffler to keep it tame.

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Supercharged111

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I know your pain, I had that same front one broken off and recessed.

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You can see what a mess it was. I zapped a nut onto that and finally got it out. I ended up making a low spot on the head, so I mudded it back in with some JB Weld to flatten it back out. Seems to be holding.
 

BNielsen

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I know it's probably difficult to tell a difference between the cam and injectors; but did the injectors add a significant boost power wise? I've got the same ones waiting to be installed, but now I'm debating on holding off; instead going with the 28# injectors when I build a motor for my truck.

Also; I dread doing studs on the manifolds, I got a free set of JBA headers I'm restoring, and I've been soaking my manifolds with Kroil for like, 2 years now.
Luckily I plan on deleting my EGR; but I'll probably still be delicate with that hose and valve.
 

Supercharged111

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I know it's probably difficult to tell a difference between the cam and injectors; but did the injectors add a significant boost power wise? I've got the same ones waiting to be installed, but now I'm debating on holding off; instead going with the 28# injectors when I build a motor for my truck.

Also; I dread doing studs on the manifolds, I got a free set of JBA headers I'm restoring, and I've been soaking my manifolds with Kroil for like, 2 years now.
Luckily I plan on deleting my EGR; but I'll probably still be delicate with that hose and valve.

Yeah, it's clearly worth $400 on Ebay. I didn't break any studs when I took mine apart, the damage was already done.
 

Papablunt

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I know it's probably difficult to tell a difference between the cam and injectors; but did the injectors add a significant boost power wise? I've got the same ones waiting to be installed, but now I'm debating on holding off; instead going with the 28# injectors when I build a motor for my truck.

Also; I dread doing studs on the manifolds, I got a free set of JBA headers I'm restoring, and I've been soaking my manifolds with Kroil for like, 2 years now.
Luckily I plan on deleting my EGR; but I'll probably still be delicate with that hose and valve.

If I had to wager a guess, I'd say the power gains were minimal at best. If I had only upgraded to larger 4-hole injectors, I'd expect things like a more complete combustion, maybe better fuel economy, and the hot start issue resolved. It is my understanding that larger injectors support more power but don't necessarily make more power by themselves. Someone correct me if I'm wrong.

Admittedly, this is my first time trying to remove a broken stud / bolt of any sort. And I have about 4" of space to access one of them. I'm struggling for damn sure, but I go by the philosophy that if you don't quit, you will eventually win. Here's to hoping it's sooner than later!
 

Piratehunter

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Still shopping for my injectors for my build. Can you share the part number and vendor for your injectors? If you would have gotten different ones, what would have been better? thanks
as I understand, the larger flow is required to support more hp, not necessarily make more, though it would seem more cam and headers would benefit like you have done, but still have to get more air into the mixture too. I’m still stuck in the past, replace a 650 with a 750 and make more power. doesn’t seem that easy with these
 

Papablunt

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Still shopping for my injectors for my build. Can you share the part number and vendor for your injectors? If you would have gotten different ones, what would have been better? thanks
as I understand, the larger flow is required to support more hp, not necessarily make more, though it would seem more cam and headers would benefit like you have done, but still have to get more air into the mixture too. I’m still stuck in the past, replace a 650 with a 750 and make more power. doesn’t seem that easy with these

I purchased from FiveO Motorsport, P/N: 0280156211.
Per Kirk at FiveO, this is an updated P/N for 2001-’04 LS1/LS6 engines.

They're listed as 24# injectors, but that's at 3 bar (44.1 psi).
Since our fuel system runs at 4 bar (58.8 psi), these injectors are actually 28# for our application.

I've been happy with these. I think they're going to support my power goals and still give me ample headroom at sea level (I'm at 6500' now).
 

Papablunt

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"Every Twenty Minute Job Is One Broken Bolt Away From Becoming A Three Day Ordeal"

I've managed to break off an extractor in one of the studs. :Insane: I must have had over 100 ft/lbs going into this guy before it broke... No stud movement whatsoever, just some bloody knuckles. I SHOULD have heated up the stud a few times before even attempting to remove it. This sucker is basically welded inside the head. It likely broke off years and years ago, and has had hot exhaust passing over it for thousands of miles. I should have known better than to give 'er the ole college try without heat.

I've just about managed to drill through the extractor, but this is certainly testing ye ole patience. Once I get the extractor out, I'm going to heat the stud several times over, then try again with another extractor. If that doesn't work, the next plan of attack is welding a nut on.

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