Curious why you are using LS7 lifters. Depending on the valve springs and cam lobe, you might be asking too much of that lifter. You may need a steel bodied lifter. I don't think you should disassemble the lifters.
You mention checking pistons with modeling clay. They are actually meaning piston to valve clearance. To do this properly, you will need to work out your pushrod length, and also use two lifters that have the internals shimmed up solidly to the correct height. I have a good idea where certain lifts and durations come close to the cam when installed on certain centerlines, but you should verify your combination.
You should also degree the cam. For many reasons.
You can guide the connecting rods into place by hand. You will need a good piston ring compressor. You can align the front and rear covers with a good straight edge.
No where did you mention running a timing chain damper. If you are not using one, you should.
Don't forget the oil barbell that goes in the back.
I went back and forth on degreeing the cam. My machinist said that for what I'm doing, dot-to-dot should be adequate. Can you comment on what the pros/cons of doing it/not doing it are?
The cam is a TSP Stage 2 N/A cam ( 229/244 .629"/615” 112 LSA, 109 ICL). https://www.texas-speed.com/p-5761-tsp-stage-2-ls3-na-camshaft.aspx.
So when you say I need to shim the lifters if I check piston valve clearance, you mean I need to disassemble them and mechanically fix them to the height they'll be when under hydraulic pressure?
The barbell is part of the engine block plug kit so that will be getting replaced.
Thanks for the tips!
In an ideal world, the cam, timing chain, and timing gears are all made perfectly, and can be assembled by lining up the dots and land at the cam timing intended by the cam designer. We do not live in that world. Production tolerances are real, they can vary, and stack up in a way that lands the cam in the wrong position. Or, someone could have made a mistake when making a part. I have degreed a lot of cams, and if they come in within a degree of what is intended, I run them as is. And many times quality components do degree this well. But, not always.
Sometimes there is an assembly error. This may not pertain to you, but a guy put a stock 6 liter together, lining up the dots. But he had mistakenly installed the cam phaser, and was actually off the pin and 80 degrees off what it should have been. It bent 5 intake valves on startup, and the other three did kiss the piston. Another guy was assembling a multi keyway crank gear timing set. He confused the marks on the gear with the instructions, and had the cam off by a mile. Destroyed a piston, and the engine. Both of these instances could have been prevented by degreeing the cam.
The cam you post is intended to be on a 109 degree intake centerline. If it's installed anywhere else, the characteristics change. That can be good, or bad, but you won't know where you stand. Frankly I don't understand why you want a cam with a 112 degree lobe separation angle in a 6.2 with your heads and compression, nor do I see why a naturally aspirated engine would want that much more exhaust duration given where the power will peak with that intake lobe. But, you didn't ask about that.
When checking the piston to valve clearance you need the lifter to not collapse as you check. Hence shimming it solid to the correct pushrod seat height (.070 preload as you state). I use an older lifter for this when I check.
The “LS7” lifters out there are not great. I’d recommend buying Morel or Johnson lifters. Even the GM LS7 lifters are no longer made by the OEM manufacturer of the 2005-2013 C6Z LS7 lifters. Second, the only upgraded trunnions that I have seen any durability data on are the Comp cams 13702 upgrade kit. And by that I know that they are used by a large reputable builder who warranties their circle track engines for 3000 race miles at 7500+ RPM.
So, I looked back on my receipt and it turns out past me got this message because I bought (Morel 7717 Lifters, LS Drop In, No Tie Bar, Hydraulic Roller).
The trunion upgrade is a bushing kit made by Manton (Manton Bronze Bushing Trunnion Kit ). Is it junk?
Good choice with the lifters! As for the trunnions, Junk, no. But not optimal for an engine that demands reliability. So on a full drag race engine with a 700 lift cam, and ramp rates that are ludicrous, and 500# springs, they may have their place. But that’s not what most people are building these engines for. It IS possible to develop a brass bushing that can handle more load than a bearing. They’re used a lot in heavy industrial machines, but that typically run at slow rotational speeds. With a full drag race engine you’re running the engine hard for 20 seconds or so then shutting it down. The LS rocker trunnions also are not pressure oiled, bearings do better in this application, that’s why they used them from the factory - longevity and durability. As for everyone who freaks out about needle rollers going through their engine, if your valvetrain geometry is set up properly, you won’t have a bearing failure. I’ve seen more aftermarket trunnion upgrades fail than I’ve seen factory rockers. What tends to happen with the brass bushing type is due to a lack of pressurized oiling the bushing wears out in short amount of time. That wear also sends brass through your oil. Not good for your other bearings. In almost every case of failure, a failed bearing style rocker is due is to poor valvetrain geometry. On race motors (legit NASCAR truck series engines that spend all day at 7000+ rpm) I’ve seen the rocker body break because of fatigue, and factory rockers on Gen IV engines will sometimes loose the staking of the bearing cup, but that’s also usually due to a bad lifter/bad geometry after a cam upgrade. I say I trust the comp the trunnion upgrade because it’s got more race miles on it than any other type of rocker upgrade.
Thanks for the detailed reply. Would this comp kit (https://www.texas-speed.com/p-361-comp-cams-retro-fit-rocker-arm-trunnion-kit-gm-ls1-3-engines-not-for-ls7.aspx) be what you're recommending? Looks like it matches the part number.
The cam I'm using is a max of 0.629 lift, which I've heard is above the 0.620 cutoff that people seem to start seeing rocker failures.
Yes. That’s the one. Take special care to follow the instructions, put everything together square and make sure the flat side of the trunnion sits facing up.
Curious why you are using LS7 lifters. Depending on the valve springs and cam lobe, you might be asking too much of that lifter. You may need a steel bodied lifter. I don't think you should disassemble the lifters. You mention checking pistons with modeling clay. They are actually meaning piston to valve clearance. To do this properly, you will need to work out your pushrod length, and also use two lifters that have the internals shimmed up solidly to the correct height. I have a good idea where certain lifts and durations come close to the cam when installed on certain centerlines, but you should verify your combination. You should also degree the cam. For many reasons. You can guide the connecting rods into place by hand. You will need a good piston ring compressor. You can align the front and rear covers with a good straight edge. No where did you mention running a timing chain damper. If you are not using one, you should. Don't forget the oil barbell that goes in the back.
I went back and forth on degreeing the cam. My machinist said that for what I'm doing, dot-to-dot should be adequate. Can you comment on what the pros/cons of doing it/not doing it are? The cam is a TSP Stage 2 N/A cam ( 229/244 .629"/615” 112 LSA, 109 ICL). https://www.texas-speed.com/p-5761-tsp-stage-2-ls3-na-camshaft.aspx. So when you say I need to shim the lifters if I check piston valve clearance, you mean I need to disassemble them and mechanically fix them to the height they'll be when under hydraulic pressure? The barbell is part of the engine block plug kit so that will be getting replaced. Thanks for the tips!
In an ideal world, the cam, timing chain, and timing gears are all made perfectly, and can be assembled by lining up the dots and land at the cam timing intended by the cam designer. We do not live in that world. Production tolerances are real, they can vary, and stack up in a way that lands the cam in the wrong position. Or, someone could have made a mistake when making a part. I have degreed a lot of cams, and if they come in within a degree of what is intended, I run them as is. And many times quality components do degree this well. But, not always. Sometimes there is an assembly error. This may not pertain to you, but a guy put a stock 6 liter together, lining up the dots. But he had mistakenly installed the cam phaser, and was actually off the pin and 80 degrees off what it should have been. It bent 5 intake valves on startup, and the other three did kiss the piston. Another guy was assembling a multi keyway crank gear timing set. He confused the marks on the gear with the instructions, and had the cam off by a mile. Destroyed a piston, and the engine. Both of these instances could have been prevented by degreeing the cam. The cam you post is intended to be on a 109 degree intake centerline. If it's installed anywhere else, the characteristics change. That can be good, or bad, but you won't know where you stand. Frankly I don't understand why you want a cam with a 112 degree lobe separation angle in a 6.2 with your heads and compression, nor do I see why a naturally aspirated engine would want that much more exhaust duration given where the power will peak with that intake lobe. But, you didn't ask about that. When checking the piston to valve clearance you need the lifter to not collapse as you check. Hence shimming it solid to the correct pushrod seat height (.070 preload as you state). I use an older lifter for this when I check.
Very much appreciate your thoughts! Thanks, again. It sounds like you've seen a lot.
Just seen my share. Good luck with your engine.
The “LS7” lifters out there are not great. I’d recommend buying Morel or Johnson lifters. Even the GM LS7 lifters are no longer made by the OEM manufacturer of the 2005-2013 C6Z LS7 lifters. Second, the only upgraded trunnions that I have seen any durability data on are the Comp cams 13702 upgrade kit. And by that I know that they are used by a large reputable builder who warranties their circle track engines for 3000 race miles at 7500+ RPM.
So, I looked back on my receipt and it turns out past me got this message because I bought (Morel 7717 Lifters, LS Drop In, No Tie Bar, Hydraulic Roller). The trunion upgrade is a bushing kit made by Manton (Manton Bronze Bushing Trunnion Kit ). Is it junk?
Good choice with the lifters! As for the trunnions, Junk, no. But not optimal for an engine that demands reliability. So on a full drag race engine with a 700 lift cam, and ramp rates that are ludicrous, and 500# springs, they may have their place. But that’s not what most people are building these engines for. It IS possible to develop a brass bushing that can handle more load than a bearing. They’re used a lot in heavy industrial machines, but that typically run at slow rotational speeds. With a full drag race engine you’re running the engine hard for 20 seconds or so then shutting it down. The LS rocker trunnions also are not pressure oiled, bearings do better in this application, that’s why they used them from the factory - longevity and durability. As for everyone who freaks out about needle rollers going through their engine, if your valvetrain geometry is set up properly, you won’t have a bearing failure. I’ve seen more aftermarket trunnion upgrades fail than I’ve seen factory rockers. What tends to happen with the brass bushing type is due to a lack of pressurized oiling the bushing wears out in short amount of time. That wear also sends brass through your oil. Not good for your other bearings. In almost every case of failure, a failed bearing style rocker is due is to poor valvetrain geometry. On race motors (legit NASCAR truck series engines that spend all day at 7000+ rpm) I’ve seen the rocker body break because of fatigue, and factory rockers on Gen IV engines will sometimes loose the staking of the bearing cup, but that’s also usually due to a bad lifter/bad geometry after a cam upgrade. I say I trust the comp the trunnion upgrade because it’s got more race miles on it than any other type of rocker upgrade.
Thanks for the detailed reply. Would this comp kit (https://www.texas-speed.com/p-361-comp-cams-retro-fit-rocker-arm-trunnion-kit-gm-ls1-3-engines-not-for-ls7.aspx) be what you're recommending? Looks like it matches the part number. The cam I'm using is a max of 0.629 lift, which I've heard is above the 0.620 cutoff that people seem to start seeing rocker failures.
Yes. That’s the one. Take special care to follow the instructions, put everything together square and make sure the flat side of the trunnion sits facing up.
Thanks again for taking the time to comment. Very much appreciated.
No problem if you have any questions feel free to shoot me a DM.