Hello all,

I can't find the answer to this online. Long story short, I am doing my first partial DIY engine rebuild project on a 5.3 gen 4. Did an AFM and VVT delete. Yesterday I installed my new rocker arms (the fancy ones from Michigan motorsports). My Cylinder 1 was at TDC and I followed the GM instructions for the torquing sequence, rotating 360 and doing the rest.

My question is, I failed to make sure my that crankshaft sprocket was at the 1:30 position before putting on the heads/front cover (its possible that it was, i just can't recall). Everything is turning over with no problems. Can anyone clarify if this is something I need to worry about or no big deal?

Thanks.

 

I've never heard of this "sprocket at 1:30" instruction. Why would that need to be done? As long as your cam timing is correct, your cam sprocket orientation after the fact is a moot point. I turn my engine over and slowly tighten the rocker bolts so they are snug, but not torqued, then bring either 3 or 5 on the drivers side to TDC on the compression stroke, or 4 or 6 on the passenger side to TDC on the compression stroke, and torque whatever one I get to first ( example: I bring 5 to TDC, torque that, then I go to 3, then to 7, then to 1, or on the passenger side I bring 4 or 6 to TDC and work outward alternating cylinders ) I've done this to numerous LS engines and have never had a problem. I think you'll be fine.

 

Thank you sir. Yeah I may certainly be misreading or misunderstanding the instructions specifically. I'll include the instructions I went by at the end of this response.

​​​​​​I didn't quite install them the way you described, I just went one by one, in order, as in the instructions, did a 360 turn and torqued the rest the same. Rotate the crankshaft until the number one piston is at top dead center (TDC) of the compression stroke. In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position. The engine firing order is 1,8,7,2,6,5,4,3. Cylinders 1,3,5, and 7 are left bank. Cylinders 2,4,6, and 8 are right bank.

With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten

.....(1) Tighten the exhaust valve rocker arm bolts 1,2,7, and 8 to 30 N·m (22 lb ft).

.....(2) Tighten the intake valve rocker arm bolts 1,3,4, and 5 to 30 N·m (22 lb ft).

Rotate the crankshaft 360 degrees.

Tighten the following valve rocker arm bolts: Tighten

.....(1) Tighten the exhaust valve rocker arm bolts 3,4,5, and 6 to 30 N·m (22 lb ft).

.....(2) Tighten the intake valve rocker arm bolts 2,6,7, and 8 to 30 N·m (22 lb ft).

 

That's the method per the book. It's the KISS approach but I've always chose the EOIC method.

 

Yeah, that 1:30 position is just a guide, no big deal. I'll actually be doing this tomorrow, as I received the pushrods for my new engine.

 

Appreciate the wisdom guys.

 

No big deal. I always just tighten the ones that are on the base circle of the cam down, then rotate the crank until I get them all torqued.

 

I was under the impression that as long as you're dot to dot you are OK. I know guys do #1 on base circle but I'm under the impression that after that you can just tighten them down to 22 ft pounds on a LS.

 

As long as the valve for the rocker you're torqueing isn't open, you're fine. You just don't want spring pressure throwing off your torque values. It takes me a few extra minutes, but I go over mine twice just to be safe.

 

I've always done this with the lifters on the base circle of the cam but once that rocker arm is torqued to 22 ft lbs it won't matter if the valve is open all the way, half the way or closed the torque wrench is still going to signal 22 ft lbs on the rocker bolt. Just sayin

 

Yes, obviously. What I was referring to is attempting to torque the bolts on rockers where the lifter is on the nose of the cam. It most definitely will affect torque values.

 

What I'm saying is that with the correct length pushrod installed it dosen't matter if you're on the base circle or not. The 22 ft lbs on the rocker arm bolt is only going to depress the spring so much regardless of where the lifter is sitting on the lobe, Now if you have the wrong length pushrod installed that's another story. If it's too long when oil pressure builds it will lift the valve off the seat when it should be closed and if too short the lifters bounce off the cam lobes which can cause damage. I'm not saying it's a good practice to just go down each bank and torque the bolts to 22 ft lbs either but in theory you can do just that when you have the correct length of pushrod with non-adjustable rocker arms.