[Dave]

I finally had the time to get the car back together aftewr the brake Mod's. While it was apart, I adjusted the valve's, but this time, I turned Them down one full turn. Usually, I turned them only a 1/2 maybe 3/4's, this time I went one full turn, in a effort to quiet it down.

It completly changed the way the Motor acts. I was VERY suprised, idle is different, belt's squeal at different RPM's. But, it still sound's like a sewing machine, but it does still rev like I stole it.

I think usually , it's reccomended to tighten only 3/4's turn.

What Ya'll think?

 

[gotago]

I think it likes a tighter lash. Maybe your studs stretched?

 

[FourEightyNine]

ummmm I only went a 1/4 on my hyrdaulic. And didnt have any valvetrain noise, never even checked it after installing the motor.

 

[FRYNTYR]

I go as close to zero as possible for high RPM applications.

 

[kettbo]

RatVette is 1/4 turn

 

[Dave]

Yeah, it seem's "too tight", I'm gonna take it out in the Morning again. Didn't help the noise, so I may as well go back to what's proven.

Damn, I hate pulling the plug's out again.

 

[ehjorten]

It all depends on preload. Most people will tell you between 0.030-0.040" of preload on the lifter plunger. Some cam manufacturers will tell you between 0.020-0.060" of preload. If you have 7/16"-20 rocker studs 1/2 turn is about 0.025" from zero lash and 1 turn about 0.050". If you have 3/8"-24 studs then 1/2 turn is about 0.021" from zero lash and 1 turn is about 0.042". If you are not measuring the plunger directly then it is highly variable on how well you are able to estimate zero lash, and how consistently.

The way I understand the system is that more lash will basically give you more top-end power and less lash will give you more low-mid power. Over lashed hydraulic lifters will pump-up and give you more lift and more duration, hence the more top-end power. You will see however that 1/2 turn on a 7/16" stud gets you pretty darn close to that tighter range of 30-40. If you have a 3/8" stud then 1/2 turn might not be enough.

 

[kettbo]

Dave,
I forget, do you have roller rockers, roller tip, or long slot stamped units?

 

[FRYNTYR]

The way I understand the system is that more lash will basically give you more top-end power and less lash will give you more low-mid power. Over lashed hydraulic lifters will pump-up and give you more lift and more duration, hence the more top-end power. You will see however that 1/2 turn on a 7/16" stud gets you pretty darn close to that tighter range of 30-40. If you have a 3/8" stud then 1/2 turn might not be enough.

More pre-load with weak springs = valve float.

If you have .050 lifter pre-load and the oil pressure is 65lbs at high RPM, that's 65 lbs working against the valve spring. That's why I usually run closer to zero lash with a hydraulic when running high RPM's so less chance of the lifter pumping up and causing valve float early.
At the most, I'll preload 1/8 turn. 1/4 if I'm not gonna race it.

 

[66 Buick Special]

hmmm... So if I went 1/4 and then pulled the adjuster and lock together another 1/8 to lock them down I might be a little tight?

Dang it I want my missing 1000 rpm.

 

[FRYNTYR]

Shouldn't, with yours, but possible. Adjust one by one with it running,,,very messy,,, and only adjust each one until the clack stops, then locks it down. It'll be close to zero pre-load.

Tammy's 69 camaro HAD weak springs years ago and it makes 80 PSI at higher RPM's. It would nose over and run best times shifting at 5300-5400. The cam now pulls hard to 7000. 120 at the seat and near zero preload.

 

[66 Buick Special]

I don't think weak valve springs are my issue.:noway:

I've got a stock valve cover here, think I'll buzz the top off of it for use during adjustments. Should cut down on the mess a bit.

If I can't replace the 5/16 line before next weekend I think I'll pull the sock while my tank is nearly empty (wow that happens fast even with the smogger heads.)

 

[Dave]

Dave,
I forget, do you have roller rockers, roller tip, or long slot stamped units?

Full Roller's.

I'm gonna take it out this Morning, it did spin pretty good last night.