Low XC

Hi all,

One of my rockers is starting to become noisey. I was told when I bought the car that it had roller rockers, and that they were adjustable. I have only had hydrualic lifters in my previous cars, so I have never needed to adjust the rockers before.
Can someone tell me what clearance I need between the pushrod and the rocker, and also what is involved in adjusting these and do I need a torque wrench to tighten the nuts on the rockers?
The engine is a cleveland 351

Thanks in advance :)

TICK4D

Hi,

You need clearence between rocker and valve spring. Now the clearence or "lash" as they call it will depend on the camshaft, as they are all different. I have a Crow cam that is about 590 thou lift and I require a .018 on inlet and .022 on exhaust.
You don't need a torque wrench to adjust these just a spanner and allen key set.

silicon

Is the cam a solid flat tappet or a hydraulic?

A flat tappet will need clearance while the hydaulic will need pre load.

xdclevo

I hope you have clearance from the rocker and spring

Low XC

Ooops, rocker and valve spring, that's what I meant :)
I dont know what cam shaft is in it, though I was told it was not hydraulic....I guess this is the problem when you buy a car with the engine already re-conditioned in it.
Without knowing the cam that is in it, how can I find out the correct clearance?
Could you take a measure of all the clearances and see if most of them are the same, so assume that is the correct clearance?
I have also been told that if you hold a screwdriver on the rocker cover you can clearly hear which is the noisy rocker...is this true, or is there another trick that can be done?

brenx

Using a feeler gauge check the clearance on your other non noisey rockers and adjust the noisey one accordingly. Generally .020 is a safe bet. You can run them tighter than specified without any problems. I've always ran a solid camshafts rocker clearances tighter than spec.

__________________
XB Fairmont (street car) 11.07@123.02mph.

Low XC

Thanks brenx

ziggs

you could measure the valve lift and then get a spec sheet of a similar cam and go with those specs. Ur method of averaging out the clearance will work although nt very accurate especially if it needs an adjustment cos of a noisy valve train. the picture i'm getting from what ur've typed is that u have one noisy rocker and the others seem fine, if thats the case and the adjusting lock nut is still tight i'd be pulling it off and checkin that pushrod incase its bent, generally rockers go out of adjustment evenly and in small increments just with wear and tear. look into it is my advise.

Low XC

Thanks Ziggs....funny as it seems, the car came with 2 spare pushrods when I bought it! I will check the locknut, and if it is still tight, I will look into your comment on a bent pushrod.
Is it common for a pushrod to suddenly bend?
It will be hard to get a spec sheet on the cam in the car, as I have no idea what it is....it certainly isnt standard.

brenx

pushrods will bent if they are not heavy enough duty for the engine or the geometry is wrong.

__________________
XB Fairmont (street car) 11.07@123.02mph.