Adjustable Rocker Arms and Hydraulic Lifters

[bwhitejr]

When I first start my 360 that has Adjustable Rocker Arms and Hydraulic Lifters. It runs rough and there is a lot of valve train noise. And it takes a couple of minutes for the the thing to smooth out. I guess it takes a while for the lifters to pump up and overcome the valve springs. Is this normal? When I revv it I get 45-50 lbs of oil pressure, but at idle it is low.

bwhitejr

 

[bOb shingler]

how did your adjust them?

 

[68 Sedan]

You're running a hydraulic cam with adjustable rockers? How much preload did you set it up for?

 

[bwhitejr]

The preoload is 3/4 tighter than zero lash. The engine runs great, idles great after the lifters get pumped up. It just takes a couple of minutes. Edelbrock requires you run adjustable rocker arms with anything above stock lift, for the heads I am using.

bwhitejr

 

[68 Sedan]

So what does 3/4 turn equate to in thousandths of an inch?

 

[scamp340]

Adjustable screws for Mopar's that I've come accross are 3/8" fine thread which is 24 threads per inch. To figure out what one turn gives you, you divide 1 by 24. This eaquals .041 of an inch. Therefore 3/4 of that is .030.

 

[340 Dart]

I am watching this because I have adjustable rockers and hydraulic lifters in my yet to be started 340.:munky2:

 

[68 Sedan]

I would think .030 would be plenty. When I had first installed adjustable pushrods in my 383 Bee I set them up with only .010 preload. (why adjustable pushrods? The class I was running didn't allow adjustable rockers if they weren't O.E.) The motor would really zing like that, but it sounded like I had a mechanical cam in it. So I went .020 with no issues.

But that was a big block. And the pushrod angle is much better on them than on a small block

 

[crackedback]

I would think .030 would be plenty. When I had first installed adjustable pushrods in my 383 Bee I set them up with only .010 preload. (why adjustable pushrods? The class I was running didn't allow adjustable rockers if they weren't O.E.) The motor would really zing like that, but it sounded like I had a mechanical cam in it. So I went .020 with no issues.

But that was a big block. And the pushrod angle is much better on them than on a small block

That's the way I do mine. .010 preload.

Usually pretty noisy but, runs right!

 

[moper]

As soon as the oil pressure comes up, the lifters are as pumped as they are going to get. Sounds more like the engine is tired or has an issue, and the parts need to be at operating temp to be "perfect". Many blocks have sloppy lifter bores by this time in their life cycle. If your pressure is low, they may be loud until the block bores and lifters expand a little and take up the extra distance. Preload can be anywhere from .010-.050, depending on cam, lifter, and setup. In most cases, louder is ok, but quiet and best.

 

[ramcharger]

Sounds more like the engine is tired or has an issue. Many blocks have sloppy lifter bores by this time in their life cycle.

I agree.