gameover4

about to reinstall my heads and wondering on procedure for valve install. i found this one below. is it that simple? no 1/4 turn past zero lash or feeler gauge distance? just turn crank right position and torque?


1) Install the rocker arms and bolts, Ensure the pushrods seat properly to the ends of the rocker arms, Lubricate Everything.

2) Rotate the crankshaft until number one piston is at top dead center of 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 camshaft and crankshaft sprocket alignment
marks will be in the 12 o'clock positions.

If viewing from the rear of the engine, the
additional crankshaft pilot hole, non-threaded, will be in the 10:30 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.

3. With the engine in the number one firing position, tighten the following valve rocker arm bolts:
Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N·m (22 lb ft).

4. Rotate the crankshaft 360 degrees.

5. Tighten the following valve rocker arm bolts:
Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N·m (22 lb ft).

redbird555

None of the lash stuff because we have hydraulic cams and non adjustable rockers.

I have done it many times following the order above as well as just torquing everything down to 22ft lbs at once.....never made a difference. I've even experimented, torqued it all at once then rotated the engine according above and rechecked all values....none changed

gameover4

so your saying the live where they live once torque? so even putting crank at tdc isnt important?

redbird555

Yes there's no lash adjustment. That's only on a solid roller car or if you have adjustable rockers. It's a maintanence free system.

And yes some people swear by doing the rotating deal and on old motors it is mecesssary. However the dozens of times I've done rockers it's never mattered in any ls. I would use a little blue loctite though either way you do it on the bolts

MTBSully

Wait so you are saying you tighten the rockers down even if the lifters are not on the base circle of the cam?

redbird555

Yes, is it the book way? No... will someone jump in here and tell me I'm wrong, 100% yes. Does that change the facts that lots of people including myself have done it this way for years and it makes no difference even after testting both methods? No it doesnt

Tech

I never had a problem on LS1 engines, although I had a friend work on something I worked on and he said a couple were loose. With my LS7, I re-checked the rockers after a heatcycle and found one loose. I have good torque wrenches. If you choose to "just torque" to 22ft lbs, I suggest you plan on checking them after the engine has warmed up at a minimum.

However, I believe TDC is the right way and will use it moving forward exclusively.

MTBSully

Not arguing it. If it works it works.

outhouse

Some are worried about stripping the alloy threads in the head, that is the only reason to place the cam on its base.

outhouse

No


You need to set preload for lifters and may require different length pushrods.

Tech

That doesn't seem likely unless your pushrods are severely oversized.

BigVette427

I was wondering about this procedure as well the last week in particular, as I'm trying to learn everything I can about the R&R procedure for my own head swap. I reached out to Kohle at AHP and he pointed to his DIY on performing a wiggle test as to the process that he uses for reattaching the rocker arms. Kohle also said that technically per the GM procedure, you're supposed to pull an engine in order to swap a cam, and I know from first hand experience, contrary to what the GM procedure says, I don't in fact have to drop my exhaust just to change my clutch fluid.

https://www.corvetteforum.com/forums...552rwhp-2.html

Dan_the_C5_Man

It's common sense to place the cam on the base circle; trying to tighten the rocker arm bolt against spring pressure is just a bad practice. You don't need to be an ASE certified mechanic to appreciate this.

realcanuk

Making sure the rocker is straight centered is obviously important. I have had rockers on and off many times without moving to the base circle and never had an issue.

Do whatever lets you sleep at night !!!

redbird555

I've probably had rockers off an ls engine 20 times. Did the base circle thing once and never again unless t was to check. I get why people do it but it's certainly not necessary. To each his own though. If I had double PAC springs with 470lb of open pressure I'd probably do the base circle thing though. But for btr duals, psi and stock it's not an issue