Rocker Arm Torque Specs
Thread Starter
3rd Gear Member
Joined: Mar 2007
Posts: 574
From: Houston, TX
Rocker Arm Torque Specs
1967 280-2V.
I put in a new cam, so I had to remove the rocker arms. I'm not sure how many lbs. to torque them to.
The shop manual mentions Valve Rocker Arm Adjusting Nut (With Tappet on Camshaft Base Circle Turn Adjusting Nut Counterclockwise) 4.5 - 15 Ft.-Lbs.
Itseems like they were tighter than 15 lbs when I removed them. Am I even looking at the correct spec?
I put in a new cam, so I had to remove the rocker arms. I'm not sure how many lbs. to torque them to.
The shop manual mentions Valve Rocker Arm Adjusting Nut (With Tappet on Camshaft Base Circle Turn Adjusting Nut Counterclockwise) 4.5 - 15 Ft.-Lbs.
Itseems like they were tighter than 15 lbs when I removed them. Am I even looking at the correct spec?
Thread Starter
3rd Gear Member
Joined: Mar 2007
Posts: 574
From: Houston, TX
RE: Rocker Arm Torque Specs
I went to the FAQ section an got two answers.
http://home.comcast.net/%7Ecobrasite...rque_specs.HTM
says 17-23 ft. lbs.
http://raceabilene.com/kelly/hotrod/valveadj.htmlsays:
[ol][*]Pick a cylinder.[*]Bump the motor until the Exhaust valve starts up. Intake is now on base circle.[*]Loosen the intake lock nut.[*]WAIT a minute or so, to let the plunger relax.[*]Twirl intake pushrod between thumb and forefinger (hold gently) and tighten the lock nut until you feel the pushrod stop turning. A little practice is all it takes. You will know - it stops right away, unless you are turning it with pliers. This is zero lash.[*]Tighten locknut 1/2~3/4 turn.[*]Bump the motor until the Intake is almost down. Exhaust is now on base circle.[*]Loosen the exhaust lock nut.[*]WAIT a minute or so, to let the plunger relax.[*]Twirl exhaust pushrod between thumb and forefinger (hold gently) , etc...[*]Tighten locknut 1/2~3/4 turn.[*]Repeat as necessary. [/ol]
Which is correct?
http://home.comcast.net/%7Ecobrasite...rque_specs.HTM
says 17-23 ft. lbs.
http://raceabilene.com/kelly/hotrod/valveadj.htmlsays:
[ol][*]Pick a cylinder.[*]Bump the motor until the Exhaust valve starts up. Intake is now on base circle.[*]Loosen the intake lock nut.[*]WAIT a minute or so, to let the plunger relax.[*]Twirl intake pushrod between thumb and forefinger (hold gently) and tighten the lock nut until you feel the pushrod stop turning. A little practice is all it takes. You will know - it stops right away, unless you are turning it with pliers. This is zero lash.[*]Tighten locknut 1/2~3/4 turn.[*]Bump the motor until the Intake is almost down. Exhaust is now on base circle.[*]Loosen the exhaust lock nut.[*]WAIT a minute or so, to let the plunger relax.[*]Twirl exhaust pushrod between thumb and forefinger (hold gently) , etc...[*]Tighten locknut 1/2~3/4 turn.[*]Repeat as necessary. [/ol]
Which is correct?
2nd Gear Member
Joined: Jan 2007
Posts: 190
From:
RE: Rocker Arm Torque Specs
Both, it depends on whether you have adjustable rocker arms (studs determine this, iirc) or not. I would try the second method first, if the nut bottoms at the correct adjustment, then you probably have the non adjustable, in which case you torque to spec.
I seem to remember seeing pictures of the studs showing the difference, but I can't remember where.
Edit: Ok, found this on Comp Cam site "Some ’67-’77 engines come with tapered (bottleneck) studs, 3/8" bottom and 5/16" top." This will be the stud that you use torque specs on, the straight stud (same diameter all the way up) you will use the zero lash-1/2 to 3/4 turn method.
as always i reserve the right to be completely and irresponsibly incorrect, and would appreciate being notified if this is the case.
I seem to remember seeing pictures of the studs showing the difference, but I can't remember where.
Edit: Ok, found this on Comp Cam site "Some ’67-’77 engines come with tapered (bottleneck) studs, 3/8" bottom and 5/16" top." This will be the stud that you use torque specs on, the straight stud (same diameter all the way up) you will use the zero lash-1/2 to 3/4 turn method.
as always i reserve the right to be completely and irresponsibly incorrect, and would appreciate being notified if this is the case.
2nd Gear Member
Joined: Mar 2006
Posts: 490
From:
RE: Rocker Arm Torque Specs
There are five different rocker arm arrangements used with the 289/302. I agree a picture would be nice, especially if your not sure if your heads have been replaced or modified.
From http://phystutor.tripod.com/stang/engines/small.html
From http://phystutor.tripod.com/stang/engines/small.html
Rail-type rocker arm with loose fit pushrod hole
289 engines built after mid-1966 and 302 engines use a rail-type rocker arm. These rocker arms have ears that extend downward, forming a rail or channel over the valve stem. This rail maintains proper alignment. The pushrod passes through a loose tolerance hole in the cylinder head, resulting in a cheaper assembly.
At high RPM, however, these rockers can jump the track, loosing alignment with the valve stem and resulting in potentially serious engine damage. These engines do not require hardened pushrods. This scheme was fully adjustable until 1970 when the studs were changed to incorporate a positive stop. The rocker arm nut is no longer used to adjust the valve clearance. Rather it is simply tightened down. Longer or shorter pushrods are selected to adjust the clearance. Since these are non-adjustable they can not be used with mechanical cams.
289 engines built after mid-1966 and 302 engines use a rail-type rocker arm. These rocker arms have ears that extend downward, forming a rail or channel over the valve stem. This rail maintains proper alignment. The pushrod passes through a loose tolerance hole in the cylinder head, resulting in a cheaper assembly.
At high RPM, however, these rockers can jump the track, loosing alignment with the valve stem and resulting in potentially serious engine damage. These engines do not require hardened pushrods. This scheme was fully adjustable until 1970 when the studs were changed to incorporate a positive stop. The rocker arm nut is no longer used to adjust the valve clearance. Rather it is simply tightened down. Longer or shorter pushrods are selected to adjust the clearance. Since these are non-adjustable they can not be used with mechanical cams.
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