Valve lash adjustment

Replaced the left side head gasket on my 351 w RH rotation-what is the proper sequence for adjusting those valves?? hyd lifters stock engine- You tube vids are all chevy's-thanks

Lakeview wrote: Replaced the left side head gasket on my 351 w RH rotation-what is the proper sequence for adjusting those valves?? hyd lifters stock engine- You tube vids are all chevy's-thanks

Since it's a stock 351 you have non adjustable rocker arms. You have stamped steel rocker arms with a bolt/ fulcrum setup.

You just assemble the pushrods, rockers, lifters etc and tighten the fulcrum bolts to 20 ft lbs.with the valve you're working on shut

Sounds kinda simplistic and it is unless you have to make an "adjustment" then you need different length pushrods to do it the right way.

If all you did was change head gaskets you shouldn't have to worry If the head was machined you might have to worry though.

I'll see if I can find a reference to cut and paste and then post it for you

Hi Tim

If he changed the cam, had head work like a valve job or had the head planed I figure he'd find some variances depending on the quality of the work, but if he replaced a head gasket with a same thickness replacement he probably won't find any issues that didn't already exist

I guess we really don't know exactly what he did

Some guys like shorter pushrods as compared to using shims for "valve train geometry " reasons.
Both work, but shims change where the rocker arm contacts the valve stem slightly.

I think the factory Lifters have about .120 adjustment top to bottom so they are not super critical but it is important to keep the geometry correct or the valves will wear funny.
The good shops I know of all pay close attention to assembled valve height to avoid issues
when they rebuild heads.

TRBenj wrote: Not sure what you mean by the lifters having "adjustment"... believe preload spec is .020-.040".

I think he's saying that the travel of the plunger in the hydraulic lifter is .12 inches.

I've seen numbers from .12 to .17 inches for plunger travel. Probably depends who made the lifters

Preload numbers between .020 to .060 is a common range.

So if you shoot for .060 for example, there's a comfortable amount of movement available in either direction. Roughly the middle of the range of adjustment

Or your .040 works but is farther from mid travel of the plunger

KENO wrote: Lakeview wrote: Replaced the left side head gasket on my 351 w RH rotation-what is the proper sequence for adjusting those valves?? hyd lifters stock engine- You tube vids are all chevy's-thanks Since it's a stock 351 you have non adjustable rocker arms. You have stamped steel rocker arms with a bolt/ fulcrum setup. You just assemble the pushrods, rockers, lifters etc and tighten the fulcrum bolts to 20 ft lbs.with the valve you're working on shut Sounds kinda simplistic and it is unless you have to make an "adjustment" then you need different length pushrods to do it the right way. If all you did was change head gaskets you shouldn't have to worry If the head was machined you might have to worry though. I'll see if I can find a reference to cut and paste and then post it for you

I think we scared Lakeview away with all this preload talk.

Here's a reference you can use to be sure the valve whose fulcrum bolt you're tightening is shut Ford Racing instructions

It tells how to be sure you're on the base circle before tightening the fulcrum bolt. You repeat it for each cylinder you're doing, in this case 5,6,7,8

Keep in mind it's written for a normal rotation auto engine and where it says to turn the engine to the RIGHT, I'd substitute the words IN THE NORMAL DIRECTION OF ROTATION.. Use a 15/16ths socket on the harmonic balancer bolt with all the plugs out and it turns relatively easily.

There are other ways to make sure you're on the base circle meaning the valve is closed but this is as good as any other way.

If all you did was change a head gasket, you can tighten everything up and be good to go.

You could check the preload if you feel like it, but in this case it should be just fine.

Keep in mind, only you know what you did so the checking preload decision is yours

Shep72 wrote: I installed a cam and GT40 Heads last summer. This is how I adjusted valves. First you shim your springs so that you have proper pre load and all springs are the same height. Once the heads are installed you put your #1 cylinder at TDC on the compression stroke. Then back off your rocker arm bolt until loose. Begin to re tighten until the rocker arm contacts the push rod. From there you want another 3/4 of a turn until the bolt is tight. If you have more than 3/4 of a turn, add a shim and repeat. Do this for all 8 cylinders intake/exhaust, torque your rocker arm bolts and your good to go.

I like it   

When a valve job is done on a set of heads each individual valve may be ground more or less than the others. Therefore your valvestems will all have different heights. Valve springs will have a set compressed height from the manufacture. In order to achieve that compressed height you will need to shim your valve springs to account for the differences in valve stem height and to be sure that all valves seat with the same pressure.

81nautique wrote: Your comment is valid but maybe not for Lakeview. .

I think his adjustment method works great.

Just to see if I was thinking right, I spent a good part of my morning replacing a valve cover gasket on the trusty old 351w powered plow truck.

It took most of the morning because I decided I'd try Shep's valve adjustment method while I was at it since it was fairly warm out.

I backed off the fulcrum bolts, and followed his technique.

Rotated the pushrod while tightening the fulcrum bolt so I knew when contact was made, then paid attention to how far I had to turn the bolt from there and for all 8 valves on that side it was right about 3/4 of a turn or slightly less. Torqued to 20 ft lbs, put the new gasket and valve cover back on. Started it up, no funky noises and it ran good

No shims needed , but then again this is a stock 351 with stock everything.

Good thing I have this old truck to run experiments on

Ken, I think this has been pretty well beaten to death but I can't for the life of me come up with a reason why you'd want to set the lifter preload at the center of the lifter's (hydraulic) travel. Seems you'd want to minimize the preload, optimally.

http://www.small-block-chevy.com/cb_6.htm

I did give too much information. But regarding Valve spring compressed height on remanufactured heads, which most people will purchase over new, three grinds, Valve, Valve seat and Valve stem will all affect Valve stem installed height. If you want to go beat up your machine shop guy because two Valve stems are 10-20 thousanths off be my guest. The guy is grinding heads not building a space shuttle. KENO thank you for the kind words.

The Automotrive Production Machine Shops, some of these build 1,000 engines per month would add 1/4 turn to the lifter adjustment so one full turn. They did this because they never wanted a warranty issue with a tapping lifter.
For racers Tim, running hydraulic lifters they would adjust as close as possible to the top of the adjustment. They would only turn the nut down till they stopped the lifter tap noise.
They did this to avoid pump up at high RPM, 6,000+. Sometimes they would tap on start up but in the race application this was done on purpose. The engine would run close to the performance level of a Solid Lifter engine adjusted this way.
The race versions of the hydraulic lifters used a much stronger spring lock to keep the lifter assembled because it was expected the plunger would be banging on the spring since it would be adjusted right at the top.