Zip Corvettes

Just like the valves, you can't beat the factory valve for the money period. GM quality checks everything and the aftermarket ?????
A very good article just came out with some testing Katech did on aftermarket valves (solid stainless) that everyone seems to swear by. That LS7 engine I referred to earlier has stock valves in it, GMPP Hi Rev lifters, will spin 8K plus but it is hampered by the stock E38 ECU and it makes 705 hp NA. You can't beat the GM parts for what they are and I am pretty sure Katech and Pratt and Miller would say the same. Now if you have unlimited funding, than you will find better stuff.

Unreal

Totally disagree, and don't think the GM lifters are even on the same level as the high end morel, or crane.

rob20rx7

Well here is the verdict,

Got to my shop this afternoon and removed the valve covers, backed out all the adjustment screws on the Crower Shaft rockers and started from scratch. Exhaust valve opening, adjusted Intake valves to zero lash then 1.75 turns (set nut is still fully within the threads). Intake valve just begining to close, adjust exhaust valve to zero lash then 1.75 turns. Wilson over at Crower tells me that each turn is .048. So looking for this .080 to .100 preload would need to be about 1.75 times ..048.

Put everything back and I don't have what seems to sound like rocker ticking or noise in the valve covers. but more like a distinctive sewing machine like sound coming from under the Fast Intake (maybe the lifters?)

car feels strong and pulls good but dont know what to make of this sound

I don't know what else to do.

Maybe try another 1/4 turn of preload tommorow? should put me around (.096)

if not that, maybe my lifters are bad? (more than one)

Unreal

Sewing machine is normal, especially with fast. Did you not have the fast before? It makes the valve train noisey.

rob20rx7

no i didnt have the FAST before. it was all done together.

So then maybe its normal then? I dont hear any rocker noise in the valve covers.

Should I just leave it like this and go to the dyno?

Unreal

Without hearing it, I would say yes. Even stock ls7 have sewing machine noise.

rio95

It's likely fine. Your procedure sounds fine IF you accurately found zero lash requiring the lifters to be all the way up. Ls7s are noisy. Mine got a lot worse with stronger springs and new cam and I don't even have headers or a fast intake which both increase noise even more.

Zip Corvettes

Can't say anything about the morel, but crane absolutely not. If you like them that much I would happily make you a deal on a set. My CRD engine had GM lifters in it because they swore by them as well. CRD is who builds most of the Rolex engines and some NASCAR stuff.

Zip Corvettes

Need to check that push rod length, that sound too long. My shaft mount required shorter push rod. I used T&D which is comp sells.

rob20rx7

Pushrod length has been verified several times by myself and 2 other engine builders. All of us came to in between .010. 8.000 was too long even with the spacer under the bracket. 7.900 was too short with 4 of the valves having to run almost 3 turns on the adjustment nut just to get zero lash.

We have ended up with 7.950 which puts me on average about 1.5 turns to zero lash then another 1.75 preload.

Maybe your heads were machined several thou deeper for the bracket? or maybe mine were machined less. I dont see any other reason we would be 1/4 of an inch off on our pushrods.

I am positive that the setup is correct though. riding right in the middle of the valve too.

Michael_D

You can't compare pushrod lengths between different rocker configurations. If you checked length with an adjustable rod, then you are golden. Just don't run the adjuster into the lock nut thread.

Some 'swishing' or very light ticking is to be expected especially if oil temp is low.

Does yours sound like mine? BTW - I am running Morel 5293's and Trend .135" wall pushrods and the same Crower set up you are. I have roughly .075" of preload on these lifters. At .060", they were singing to me at high rpm so I gave them another quarter turn and they quieted down.

Unreal

If he had basically a stock build, I would agree with the GM lifters, but he has complete aftermarket. 6 bolt heads, Crower shaft rockers, etc.

LME who builds a ton of high HP 2000+ cars suggested the cranes, and that is what I would put it. Just put a set in my friends car. The ultra billet ones. Yes they are $750 a set, but they are a work of art.

MTIRC6Z

Instead of counting turns why not put a dial indicator on and get a REAL measurement? On my last build (with the engine on a stand) I played around counting turns and then took REAL measurements, there was a difference! For example do you count the turns until you hit 23 ft.lb. of torque, because just tightened down, to properly torqued, is usually about a 1/4 turn and do you know how that impacts the preload measurement??? I could go on with more examples but suffice to say that you'll find them yourself if you actually use a dial indicator to take the measurements, oh and do both intake and exhaust as well as the front and the rear of the engine.

Also, from my experience 60-80 thou is a little tighter than necessary for high rpm (that's where I run my V with shift points of 6300) but on my Z I run 30-50 preload because it sees 7000 regularly. Personally I don't think how things sound should be impacting your preload setting, an actual measurement combined with your intended use should be what determines the preload.

BTW, don't know why, but around here (in Canada) a set of stock LS7 lifters (PN 12576400) cost me $337, where as the lifters from the GMPP catalogue (PN 12499225) cost me $141...go figure??? Personally I don't think there's anything wrong with GM lifters but then I don't go beyond 7100 rpm and only have .670" lift...your needs may be different.

Cheers, Paul.

vertC6

How is the dial indicator used to measure preload?

Michael_D

If you can position it on the rocker over the pushrod, it works great. Just find zero lash, zero the dial and run the rocker bolt home. You cannot do that with the Crower rockers though.

rob20rx7

Drove the car around today, put about 60 miles on it.still has a sound and sounds like maybe its too tight with that 1.75 turns. the sound is more of a tapping and it is resonated with the same rhythm on the valve covers and the intake manifold. when you throttle it up. the tapping is more apparent even through the engine throttles smooth. like a really loud sewing machine

I think im going back on Monday to readjust the damn valves again, ;(

Michael_D

When I set lash (or pre-load in this case), I roll the engine by hand with all the plugs pulled. I'll do one cylinder at a time, following the firing order. I roll it and watch the valves close. After the exhaust closes > then the intake, you know you are compression stroke, and the lifter will be riding the cam's base circle. Back off on the adjuster and give the lifter a few minutes to expand. Then find zero lash by gently lifting up on the rocker while running the adjuster down by hand. Then count turns to get your desired pre-load.

MTIRC6Z

Should probably mention that the easiest way (at least for me) to turn the engine over by hand (with the plugs pulled) is to have a socket on the alternator bolt and let the belt do it for you...not sure if this is common knowledge.

Cheers, Paul.

lt1z

Johnson

blkbrd69

Think of a hydraulic lifter as a matched metered orfice.

If you increase spring pressure beyond its match for the needed bleed down it will have more clearance IE noise than stock.

In mine with a .650" lift cam, stock lifters and dual springs I get "alot" more sewing machine valve lash noise than stock.

A bit thicker Redline oil does help a bit.

Can you hear the sewing machine noise??