[Tarl]

Which is the best method for cold rocker arm adjustment? unless they are the same when you work out the numbers, but I can't see it.

http://www.bafb.org/1968firebird.org...harticles7.htm

http://www.boyleworks.com/ta400/psp/rockers.html

[rustyrelic]

I prefer option #2. Less effort in turning the engine and looking at timing mark alignment. Works well for me.

[Blued and Painted]

The running valve adjustment method was developed under a shade tree back in the 50's. IMO.

[jonmachota78]

Neither!

1 turn crank to tdc.
2 loosen all rockers
3 set all rockers to zero lash
4 turn crank exactly one revolution (back to tdc)
5 set all rockers that have loosened to zero lash
6 add your favorite preload to all rockers and lock them down (I like 1/2 turn)

[David Jones]

Originally Posted by jonmachota78

Neither!

1 turn crank to tdc.
2 loosen all rockers
3 set all rockers to zero lash
4 turn crank exactly one revolution (back to tdc)
5 set all rockers that have loosened to zero lash
6 add your favorite preload to all rockers and lock them down (I like 1/2 turn)

Is that not Bill Boyle's method explained differently?

[Schurkey]

Originally Posted by David Jones

Is that not Bill Boyle's method explained differently?

No. Boyle's method is slower and needlessly complex. He specifies certain valves to be adjusted in a sequence. That is completely un-needed, they can be done in three steps by tightening ALL of them to zero lash, turning the crank one revolution, then tightening only the loose ones to zero lash. Then tighten ALL of them "your choice" of preload, typically 1 full turn or less.

I also disapprove of him saying that the rockers need to be "adjusted" but failing to specify that the rocker studs and nuts may need to be replaced to achieve an adjustable valvetrain.

Since when do rockers need to be made adjustable just because the heads have been milled? If the lifter plunger has enough travel, the net-lash system will be just fine. I've seen lifters with nearly a quarter-inch of travel.

[David Jones]

Originally Posted by Schurkey

they can be done in three steps by tightening ALL of them to zero lash, turning the crank one revolution, then tightening only the loose ones to zero lash. Then tighten ALL of them "your choice" of preload, typically 1 full turn or less.

Never seen this method before and I swear I called myself looking.

Starting with #1 at TDC?.....with #1 at TDC (compression?) set all of them to zero lash then turn the crank one revolution and adjust only the loose ones to zero lash. Then in no particular order simply set the pre-load by (this is my #) adding 3/4 turn of the adjuster nut and locking them all 16 down?

"loose ones" being the rockers?

Just looking for clarification because it seems....to simple.

[Old Man Taylor]

Originally Posted by jonmachota78

Neither!

1 turn crank to tdc.
2 loosen all rockers
3 set all rockers to zero lash
4 turn crank exactly one revolution (back to tdc)
5 set all rockers that have loosened to zero lash
6 add your favorite preload to all rockers and lock them down (I like 1/2 turn)

That's only good for hydraulic lifters.

[jonmachota78]

Originally Posted by Old Man Taylor

That's only good for hydraulic lifters.

True ^^^^^^^^ I should have specified that.

For this procedure to NOT work, the base circle would have to be less than 360° duration. (Expressed in crank degrees. There's 720 crank degrees on a cam, right?).
For that to happen the advertised duration of the lobes would have to approach or exceed 360°.
That's a big honkn bump stick! Hydraulic cams generally don't get near big enough to worry about that being an issue. I would think like screamingchief eluded to that's solid race cam territory. But I'll be the 1st to admit I have NOT seen it all!

The concept behind this procedure is that at Any given point on a cam lobe, 180 cam degrees from that point will be base circle. When you turn the crank 360° you're also turning the cam 180° so all lifters will hit base circle on one of the two cam positions.

[old66tiger]

I do it the simple way. Locate #1 TDC, #1 timing mark. Adjust # 1 cylinder both intake and exhaust. Turn the crank 90 degrees, adjust #8, turn 90 degrees, adjust #4, etc for 3, 6, 5, 7, and finally #2. Point being is that every adjustment, you will be at top dead for each cylinder for compression/firing sequence and the cam had better be on the base circle or you have some serious problems with your cam timing. This method keeps a guy from having to remember when things are opening and closing and what cylinder you are on.

[steve25]

Also note that on alumminum heads with there expansion rate that your valve lash will open up by .007 to .010" when hot so you need to factor that in.

[78w72]

although alll the mentioned steps should work fine, & yes the procedure from jonmacho sounds too easy it probably works fine too.

but what is wrong with the common way of doing each valve when its verified to be on the base of the lobe? might require additional turning of the engine but you are sure the base of the lobe is properly located, fool proof accurate way to do it.

as mentioned, these "quick" ways of doing it dont ensure the lifter is on the base of the circle. the procedure in most chilton type manuals for adjustable valvetranes are for stock or close to stock "mild" street cams. once you get into larger duration cams, those procedures dont work because the valves they say to do at any given point of engine rotation arent always on the base of the lobe.

i like jonmacho's steps & may give that a try next time i need to adjust all the rockers, but the foolproof way is to just do each lifter individually.

http://www.dragzine.com/tech-stories...sh-like-a-pro/

[screamingchief]

Originally Posted by 78w72

as mentioned, these "quick" ways of doing it dont ensure the lifter is on the base of the circle. the procedure in most chilton type manuals for adjustable valvetranes are for stock or close to stock "mild" street cams. once you get into larger duration cams, those procedures dont work because the valves they say to do at any given point of engine rotation arent always on the base of the lobe.

Agree,but dont be surprised if you get a lot of people that will argue this with you.

But in their defense,those are likely cams best discussed in the drag forum.

Having BTDT,when you try these "quick" adjustment methods with a big 'ol solid roller,there's a real good chance that the engine is'nt even gonna start because it'll be hanging the valves open.

And yep,the only way to be sure that does'nt happen is to do them a cylinder @ a time,either by adjusting the rockers for each cylinder @ TDC compression,or by using the Exhaust valve just opens/Adjust intake ~ Intake valve just closing/Adjust exhaust method that some cam co.s recommend (Crane et-al).

FWIW

Bret P.

[David Jones]

I just finished swapping valve stem seals. I'll be using this method in the next day or two.

[Blued and Painted]

If the distributor is in correctly, adjust the 2 valves on the cylinder the rotor is pointed at.

[David Jones]

Worked like a charm. Loosened all lock nuts. Pulled it around to tdc line / zero and took every rocker to zero lash. Rotated the crank one revolution. Zero lash on the loose ones again. Then added preload to each nut and locked them down. Really just took a few minutes. Engine runs great.

[68 Firebird]

wow learn something new every day

Gerry

[David Jones]

80 miles later. Never ran better. 58 degrees and the sun just peeking out. Great morning to have a "big block" Pontiac.......

[72LuxuryLeMansLa.]

Originally Posted by David Jones

80 miles later. Never ran better. 58 degrees and the sun just peeking out. Great morning to have a "big block" Pontiac.......

Boy, you're looking to stir it up aren't you?

58°F, damn that must feel good!

[Derbs24]

Great tip thanks! I've always done certain valves through 2 complete revolutions. Guess I can throw away my yellow crayon I use to mark which ones I've done. If you've ever adjusted valves with your little kids round you know why I do this! I call it the "hey dad!" factor.