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Personally I hate the sight of RTV on exhaust parts, if there is a big enough gap that you need RTV to seal, it will get blown out anyway. IMO
I had great luck with no gaskets. Sounds backwards, but works great. And again, if everything is flat it will seal, and if everything is flat it doesn't need RTV or a gasket.
14 Silverado 1500, 5.3
Have lt1 injectors also. Trying to decide to add meth or go all out and buy lt4 injectors and Pump. Will be tuned at weaponX in Cincinnati. My goal is 6xxwhp
Have you looked into piston durability? I've got a 6.2 sitting right here but was told that the DI pistons are fairly brittle and should be changed(and rods while you're at it) to hit much over 600WHP. If it were like the typical LQ4, I would have just swapped it in rather than screw around with the exhaust bolt holes on the 5.3. For now, I'll try to get some miles out of this setup and then build the 6.2 in spare time...when I find some.
Finally got off my a$$ and did the exhaust manifold Time-Serts. Really wasn't that bad and feels like a professional repair that should be stronger and more durable than what was there before. I left the one stud in the rear as that sucker is really IN there. I don't expect it to be an issue and it helps align things.
The shallowest hole is ~22.5mm and the Time-Serts state you need +6mm so that the driver tool can properly form the threads and lock the insert into place. So I used the 16.2mm stainless inserts. Manifold is 11.85mm thick and bolts are 25mm = 13.15 thread engagement. I could theoretically get some 30mm bolts in there but probably just roll with this.
Exhaust was leaking BADLY here. No doubt about that. And the holes were more shavings than threads.
Got some drill stops. They basically suck and don't fit well, but combined with electrical tape, that can be made to work fairly well. Set all these to ~22.5mm and let it rip. I did use a 90 degree drill adapter for the front two holes. I blew out with air between each step.
Drilling was pretty straightforward. Very sharp bit. I didn't oil for the initial drilling. Probably should have but it seems to go well.
Next is the countersink. It is stepped with a flat section so that you drill until it stops. This is a non-event.
Then comes the tap; I actually have real cutting oil for this. Good stuff and worth having. It's more of a sticky foam and really collects the shavings as well as lubricating. If you don't have a ratcheting tap driver, get one. Total time saver. When the tap is almost all the way out, I remove the driver and work the remainder by hand as to not harm the outer threads.
I then used brake cleaner followed by more air to get the holes very clean and dry. Rocksett is a ceramic glue that apparently is good to over 1100C. Engine oil on the insert driver and Rocksett on the outside of the insert. Thread in. You can really feel things tighten up when you hit the bottom of the insert and expand it. About 2-3 turns and then the resistance goes away right before you bottom out. That's when you know you are done. Pull out the driver.
The driver is not totally round but rather squared which I found interesting.
I then shot the holes with brake cleaner and air again to ensure no Rocksett got in the new threads. Unlikely but I don't want to do this again. I think the repair looks good and it was *really* satisfying to thread in the new bolts with no resistance or funk. Makes me want to Time-Sert all the same on the 6.2 before I put it in.
Time to coat the manifold and get this thing back together!
glad to see you have it buttoned up. get that manifold cleaned up so you can go do burnouts. What year 6.2 do you have? I would think its pistons and rods are the same material as the 5.3s and they make 600 wheel with OEM parts. The 6.2 should make it with less abuse of FI so i would think be safer????
Have you looked into piston durability? I've got a 6.2 sitting right here but was told that the DI pistons are fairly brittle and should be changed(and rods while you're at it) to hit much over 600WHP. If it were like the typical LQ4, I would have just swapped it in rather than screw around with the exhaust bolt holes on the 5.3. For now, I'll try to get some miles out of this setup and then build the 6.2 in spare time...when I find some.
I look forward to seeing what you do with it!
Weapon X has built 3-4 l83s with around 650 with no problems. There are 5-6 on youtube either spraying meth or with a cam making low to high 600's. Everything I've read says stay under 700, whether that's true I don't know. I think I'm just going to throw all my parts on then take it to Weapon X and tell them to tune it safe. Throw 10-12lbs of boost at it and whatever number I get I'll be happy with. I went with meth injection btw. Hoping to put my mind to rest about knocking. Praying to god I don't run into issues like you've had. That's my worse nightmare!
I'd go with 30 mm bolts. If you don't run a gasket 25mm would be the minimum I would do, and I'd still wish I had done 30's. With the inserts and the flange you need 27 mm. Yeah you can get by with 25, but with clamping and load support being so important now, I'd go for max threads, not "enough".
Funny thing is, I'm pretty sure the OE bolts are 30 mm
Studs would give you a little more thread assurance since they don't thread in and out, they stay put, and if something goes bad it'll be the exposed threads and you can just pull the stud out and slap a new one in instead of all this that you just had to do.
Last edited by 00pooterSS; 07-24-2018 at 05:19 PM.
07-16-2018, 08:33 PM
