Rocker Arm Adjustment

[Brent13]

Can someone post a link, or explain the proper method of adjusting rockers/valves on a 1974 302? I have watched 20 YouTube videos, and they all seem different. I have had a rocker loosen up, #1 exhaust. Need to figure out why, and then will need a adjust properly. My rockers are roller tipped if that makes a difference. Last time I adjusted these rockers, I brought the cylinder to TDC, and adjust the intake and exhaust rockers by tightening down the nut while rotating the push rod. When the push rod stopped rotating, I went a full turn further on the nut. Is this proper procedure?

Thank you

 

[rmk57]

Tighten down the nut so there is "0" lash, you should still be able to rotate the pushrod easily with your fingers. I give them about 1/2 to 3/4 turn after that.
There is supposed to be around .060 lifter preload.

 

[oleguy74]

if that engine is stock,torque rockers to 18-22 ft lbs.they are a positive stop type.read rocker specs for roller tip as they may have to be set different.

 

[Brent13]

And based on both of these replies, this is done on both rockers when that specific cylinder is at TDC, correct???

One more question, how does one tell a lifter has failed? Trying to figure out why this one rocker got sloppy on me, and was making one hell of a racket.

I don't have any idea what components were changed on this engine. Rockers were obviously changed, they are roller tipped, other than that, no idea.

Thank you

 

[bmc69]

And based on both of these replies, this is done on both rockers when that specific cylinder is at TDC, correct???

One more question, how does one tell a lifter has failed? Trying to figure out why this one rocker got sloppy on me, and was making one hell of a racket.

I don't have any idea what components were changed on this engine. Rockers were obviously changed, they are roller tipped, other than that, no idea.

Thank you

Only one of the two replies was actually correct. Your engine does not have adjustable rockers. Just tighten them down to 18 ft lbs...order matters nothing. Sloppy rockers are due to excessive cam lobe or lifter wear or, the pulling out of the rocker stud.

 

[Brent13]

So torque all to 18 foot pounds, and do not worry about TDC? And then hope all is quiet with the rockers? If I have rockers making noise, then I have wear on cam, lifters, etc., and will have to dig further?

 

[DJs74]

So torque all to 18 foot pounds, and do not worry about TDC? And then hope all is quiet with the rockers? If I have rockers making noise, then I have wear on cam, lifters, etc., and will have to dig further?

Anytime you are adjusting valves... you should do so by beginning at TDC and ensure that the lifter of the valve you are adjusting is on the heel of the camshaft lobe. If you adjust the valve (even positive stop / torque to spec rockers), at any position other than on the heel of the lobe, you will be torqueing / fighting against the valve spring and put unnecessary stress on the rocker stud / nut because you'll be compressing the spring with the rocker / rocker arm nut.

I use the EOIC (Exhaust Opening Intake Closing) method.
Adjust the intake valve as soon as the exhaust valve would begin opening or when the exhaust pushrod begins to move up.
Adjust the exhaust valve after the intake valve reaches max lift and begins down the ramp to close.
This simply ensures that the valve you are adjusting is at its fully closed / seated position in the event.

DJs74

 

[Brent13]

Well, go all back together last night, test drive of a couple miles, all was good. Drove to work this morning, about 6 miles into the drive and the tick is back!!!! I believe the same rocker has gone sloppy again. What would be next in the diagnosis? It held together for a few miles and now back to the same problem. Could I have lifter issue? What would you all do next. I am thinking seriously about pulling the motor and going thru the entire top end. I am waiting on a tow now, I fear driving it any further could do serious damage that could not be undone.....

 

[half cab]

put a jam nut on it.

 

[Justafordguy]

You need to determine if the nut backed off or the stud is pulling out of the head.

 

[bmc69]

Anytime you are adjusting valves... you should do so by beginning at TDC and ensure that the lifter of the valve you are adjusting is on the heel of the camshaft lobe. If you adjust the valve (even positive stop / torque to spec rockers), at any position other than on the heel of the lobe, you will be torqueing / fighting against the valve spring and put unnecessary stress on the rocker stud / nut because you'll be compressing the spring with the rocker / rocker arm nut.

I use the EOIC (Exhaust Opening Intake Closing) method.
Adjust the intake valve as soon as the exhaust valve would begin opening or when the exhaust pushrod begins to move up.
Adjust the exhaust valve after the intake valve reaches max lift and begins down the ramp to close.
This simply ensures that the valve you are adjusting is at its fully closed / seated position in the event.

DJs74

Been an automotive machinist and engine builder for more than 30 years; simply bolting the non-adjustable rockers right down to spec has never caused the first problem. If it's a rebuild and machine work was done on deck and/or heads, it's always a good idea to see if the lifter preload is still in spec when the rocker is tightened down; in that case following the EOIC or TDC-firing order methods is necessary. But if simply putting one back together with no changes, no need for all of the extra trouble. The head studs or bolts have a tensile strength that is thousands of times greater than the 150 or so pounds the valve spring exerts.

 

[gotdads68]

You need to determine if the nut backed off or the stud is pulling out of the head.

^This, if neither is the case you're going after a collapsed lifter or possible flat cam lobe based on your descriptions.

 

[Brent13]

Will be back into it this week. If the stud is pulling out, what is the fix? Pull the head and off to a machine shop?

Thank You

 

[Brent13]

Ok, think I have 100% certainty that the nut is backing off. Not sure how, nuts were new about a year ago, but this one has now backed off twice. The last time, less than 10 miles and I was chattering like crazy. Why would this nut back off? And is a nylon nut the answer, double nut each rocker arm stud just to be safe? Picture shows the difference in thread showing on the stud, it backed off a long way compared to the other on cylinder #1.

 

[DJs74]

Could be that the nut is cracked / split. I had this happen on a factory 5/16-24 nut but the ones in the photo look fairly new to me.
You might consider getting rid of the staked style nuts and install a set of polylock nuts.
You can search them online or at Summit Racing.

There are a couple of mentions / questions about the stud pulling out of the cylinder head but if that were happening, there would be more stud threads showing than less because the nut having to be continuously retightened and torqued each time the stud pulls out would put the nut further down on the stud.


DJs74

 

[Justafordguy]

Sure looks like it's backing off to me. I would double nut it and see it that helps.