luckyou03

iTrader: (8)

i turned the pushrod till it wouldn't spin anymore, then about another 3/4 turn, then locked them with poly locks.

There NSA 1.6 rr with guideplates and harden pushrods.

DeltaT

iTrader: (5)

The hot cam is a ZERO lash cam which requires no hydraulic lifter preload. All you want is tight enough so the pushrod spins, but needs a little force to spin it. No more preload. Try adjusting your valve like that, and I think you'll be happier. If you put preload on a 0 lash cam the valves never completely close and you lose power and compression.

The specs from GMPP are:

Part Number: 24502586
Engine Application: SBC - Gen 1, Gen1E, and Gen 2 1986 to present.
Lifter Type: Hydraulic Roller
Engine RPM Range: 1500-5500
Part #: 12551483 Single: X Dual: Triple:
Outside Diameter: 1.32” Pressure At Installed Height: 101 lbs.
Installed Height: 1.780” Valve Spring Seat (shim): 10212809
Solid Height: 1.215” Valve Spring Retainer (cap): 10212808
LOBE SEPERATION 112°
DURATION AT .050” (Duration measured @ cam lift.) Intake: 219°/Exhaust: 228°
DURATION AT .006” (Duration measured @ cam lift.) Intake: 272°/Exhaust: 281°
LOBE CENTERLINE Intake: 109°/Exhaust: 115°
LOBE LIFT Intake: 0.328”/Exhaust: 0.328”
GROSS VALVE LIFT (1.6 Ratio Rockers) Intake: 0.525”/Exhaust: 0.525”
GROSS VALVE LIFT (1.5 Ratio Rockers) Intake: 0.492”/Exhaust: 0.492”
VALVE ADJUSTMENT Intake: Zero Lash/Exhaust: Zero Lash

I had similar problems on my ZZ3 motor. It makes a big difference, and makes the motor sound like it has a bad exhaust leak!

The best adjusting method I found was to set them by hand with the motor off then use a cheap mechanic's stethascope to listen on each rocker arm until I minimized the ticking sound of that valve, with the motor running and warm.

For tightening, I use one of the Summit Wrenches that have a built in Allen wrench included. Adjust, then hold the bolt and torque down the set screw TIGHT. It's the set screw that holds the tightness. Never had one come loose after someone turned me on to that method. Here's the wrench:



Jim

matt94z

iTrader: (49)

Hey man, when I ran the tb, I set the tps at .45 and it idled perfect at 750 rpm's. But I have no idea of what your cars doing.

luckyou03

iTrader: (8)

i'm not really worried about the idle right now, i'm more worried about the knock and weird 02 readings with two similar tunes.

buffman

iTrader: (9)

Personally I think you get better results adjusting them while car is running. Zero Lash would be when you loosened the rocker enough for it to "clack" and then slowly tightening it down till it stops clacking. What I and a lot of guys have found, once you loosen them you'll find retightening the poly lock by hand that the rocker will come to zero lash when you feel resistance on the lock. Then set lash, tighten screw and you're done.

Im sorry but looking at that post above, there is NO SUCH THING AS A ZERO LASH CAM. Lifters dictate the amount of preload. Unless you changed your lifters, 1/2 Turn minimum is recommended...

DeltaT

iTrader: (5)

I agree with the motor running part, as I said. I'll stick by the zero lash - it is the stated GM spec for the HOT cam, not all hydraulic roller cams. I took that spec right off Sallee Chevrolet's site. Zero lash means there's always contact between all the valvetrain parts with no slop, and no preload on the lifters. I doubt if I put even an 1/8th turn on mine, after finger tightening, to stop the noise. Any more and performance would drop off immediately.

Jim

buffman

iTrader: (9)

Lash and preload are TWO sepperate items. Hydraulic cams require ZERO lash, solid lifter cams may require .010" lash. THEN, a hydraulic cam will require PRELOAD, anywhere from 1/4 turn to 3/4 turn. No preload depending on the type of lifter, and you will end up with a rattle bucket.

DeltaT

iTrader: (5)

OK, I agree with your point about lash, although if you left them too loose you could end up with some. When I was having my ZZ3 valve adjusting problem, I talked to the engine builders at Sallee, and they told me that cam and the HOT cam were designed for Zero Preload, using the technique I described. I did what they said, and had to let go of some old school hydraulic lifter lessons, and got excellent results.

Jim

buffman

iTrader: (9)

okay simple enough. Im prolly just mixing things up in the old brain of mine