# Rocker arm adjustment



## ozboz (Jan 1, 2011)

New user - Happy New Year to those already there. arty:

I've scoured the forum, the net and old books, Haynes manuals and I'm still scratching my head. :confused I'm sure this has been beaten to death.

I've the following 455 setup for street/strip use 2500 stall/OD/3.42;
041 Cam 308/320 231/[email protected] with .470 lift (@1.5 rocker ratio)
Crane hi-intensity hydraulic lifters (no presoak)
Magnum rockers (1.52)
9.146" pushrods
7K3 heads - look shaved at the intake/head side. New valves, springs, machined, etc.
Standard FelPro head gasket (not 1016s)
TRW slugs with the 6cc valve relief (Speedpro LF2359s I guess it is now)

Logic tells me that the rockers and shaved heads, coupled with the pushrod length, will generate more lift than @ .470. It's not nearly as bad as having 1.65 rockers and having to elongate pushrod holes.

Will I have a problem with lift? Coil binding?

Can I torque the 3/8" nuts to 20 ft-lbs with this combination? 

I want to say no, that I should treat this as an adjustable valve train and spin the pushrods until there's no play, then rotate 'em another half a turn. That's based on reading about any swaps with newer cams or machine work on the heads/block ever occurring. Since this is a blueprinted 041 old school cam, does this rule still apply?

Also, should I go to 7/16" BBC studs and polylocks or just run it?


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## ozboz (Jan 1, 2011)

I found this rant on another site. I'd adjusted the valves in a similar fashion using the up/down method by holding the pushrod into the rocker relief and letting it touch the lifter, then adding a half a turn.

It didn't look right - the rockers were all at the same height. I realize now that it's simply due to no oil being in the lifters and lifting the valve.

So I torqued the number one intake rocker down to 20ft-lbs and watched the pushrod plummet into the lifter. That looked wrong too.

Then I read about the twist method of adjusting valves and thought that was a better way to go.

The guy's comment below is spot on about setting a pushrod on a lifter and watching it compress.

Still wondering about lift/coil binding.

__________________

<snip> People always call me AFTER they use the "twisty turny" method and have punched holes in their pistons, bent their valves and/or pushrods. Then they ask... "I followed the Service Manual Procedure", what did I do wrong?

The twisty turny method is described in just about every service manual I have used.... and it's a bogus method.

Why? Because the lifer plungers do not always exhibit a uniform amount of back pressure or resistance to compressive forces. The point at which the pushrod stops turning depends on how hard your built in rotometer is set. Just like your built in torque wrench for tightening main bearing caps. 99% of the time, this is not zero lash.... it's almost always PAST zero lash. When I was still in business as a Machine Shop owner/operator, I gave seminars on this procedure. On any given day, I could take a new box of lifters off the shelf and use the twisty turny method of adjustment with them... and get bogus lifter pre-load settings every time. My "students" were amazed. It's worse with used lifters. The design of the lifter, the internal valving & spring, and the amount of oil currently in the lifter influence how much compression the plunger will take before your "twisty" stops twisting.... It is a non-determinate point, and it gets people into trouble... even the self proclaimed "pro's".

Zero Lash is when all slack has been taken out of the valve train with the lifter on the base circle of the cam... and in the case of hydraulic lifters.... when the push rod is touching but NOT pushing in on the lifter plunger. By the time the built in rotometer in your fingers says it's time, it's too late. I have seen (and shown others) hydraulic lifters compress with just the weight of the pushrod sitting on them.

Been preaching this for years on this forum... but I always get arguments. Take yer chances, pay yer money.

Do it this way.... forget what y'all read in books... this is real world experience... not an opinion.

Following the sequence you prefer, get the subject lifter on the base circle of the cam (lifter is not being raised by the cam lobe).
If not already loose, loosen the rocker until you can see/feel slop between the rocker, pushrod, and lifter.
Hold the rocker firmly against the valve tip.
While continuously moving the pushrod -GENTLY- in the direction it moves while running (up & down) slowly tighten the rocker nut until you can see/feel no clearance... watch the lifter plunger.... make sure it does not compress.... it may be rock solid, or it may be exhibiting no resistance to compression at all, so you have to watch it carefully. If it starts to compress, you have gone past zero lash. Back the nut up & try again.

At zero lash.... adjust the additional number of turns specified by the lifter manufacturer... varies based on manufacturer, thread pitch of the rocker studs, engine, etc,

I used this method in my business for about 30 years and NEVER had to re-adjust hydraulic lifters.... I put the valve covers on & was done.


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## 66tempestGT (Nov 28, 2009)

i dont know where your springs coil bind but different pushrods and shaved heads dont change the lift.


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## dimitri (Feb 13, 2009)

If you are not spinning the engine over 6,000 for a sustained time, a new set of factory style locking rocker arm nuts are fine. Then you don't have valve cover clearance issues. It is criticle that there is no oil in the lifter. If there is, rotate crank in correct direction a couple of times allowing valves to open and close a couple of times. Wait about 20 minutes for lifters to bleed. Then start at #1 when the ex valve just starts to move adj intake zero lash plus 1/2 turn. Go through the firing order doing all intake. Then back to #1 ex rotate eng till intake on maximum lift and half way down adj ex the same as intake. Continue down the firing order until all are done.


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## ozboz (Jan 1, 2011)

Yeah, I didn't know if they'd bind or not. The cam lift IS the same, however, with a different pushrod & shaved heads I wanted to say the valvetrain geometry would be affected. Think 1.65 vs. 1.52 vs. 1.5 - they all yield a different total effective lift based on the cam grind.

After more research, I was thinking the most accurate way to determine that geometry was with an adjustable pushrods and a dial indicator.

Instead of that, I adjusted the valves on #1 and used the marker on the top of the valve stem, rotated the engine with the balancer 720 degrees - the rollers left marks maybe a 1/32" towards the exhaust side of the head. I think I'm running 'em as is.



66tempestGT said:


> i dont know where your springs coil bind but different pushrods and shaved heads dont change the lift.


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## dimitri (Feb 13, 2009)

The guy that did your machine work will have to shim the springs for spring heighth to provide the rated spring pressure. He will know if these are the correct springs.


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## 66tempestGT (Nov 28, 2009)

i see what you mean. coil bind is when they press down so far that they cant go any farther. your stuff sounds like it will be fine. you have to get in some pretty radical lift and rpms before there will be many issues with geometry.


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## tyler t (Aug 15, 2010)

ozboz said:


> So I torqued the number one intake rocker down to 20ft-lbs and watched the pushrod plummet into the lifter. That looked wrong too.



thats what i did and i broke a pushrod and bent another. i dont recommend it.... i know know how bad of a decision it was and wish i knew before hand


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