Lash adjuster length below rocker?

[Beekeeper]

How many threads below the rocker do you guys normally set up your lash adjusters? Ray Barton recommended 3 to 4. 426 Hemi with roller cam and stage V heads and roller rockers.
I measured the first set with 4 threads and the lifters ended up being the wrong ones for my block so I got the correct ones now ordering new push rods again?

 

[F4R/T]

Good question my small block is either eating the cam or my adjuster spit off again. I’ll measure valve travel in the am but I’m curious as I think 3-4 threads is all that is wanted.. I have old 273 rocker arms on mine.

 

[MoparMur]

Don't quote me with being right, but here is my thought: Get a pair of adjustable checking pushrods as required for the type of engine you're working on, one for the exhaust side, and one for the intake side (may be different lengths depending on engine type). Set the heads up with checking springs for one cylinder (after the heads have had a valve job, or are ready to install), bolt the head down with the right gasket, and adjust the rocker to have equal thread protrusion below the rocker and above the locknut. Install lifters for the cylinder you're checking. If using hydraulic lifters, take two used lifters, disassemble them, and install shims or spacers to put the lifter cup in a fixed position in the middle of normal lifter travel. With that done, adjust the pushrod length to the point where the rocker arm is contacting the top of the valve in the center of the tip all the way thru the cam's rotation. The contact point will move from one side of the valve stem tip to the other (more noticeable with a higher lift cam), but should never run off the side of the tip of the valve. If all the components are matched properly, you will be able to adjust the pushrod length (not the rocker adjusting screw) to get a contact pattern that, thru the rotation of the engine, will average out to be centered on the valve tip. Then measure the lengths of the pushrods and record. Don't cheap out; check every cylinder. If all looks good when done, order the correct length pushrods as required. If you spend the time to do this, you'll have a good bullet-proof valve train. One final thought: Make sure that AT NO TIME does ANY part of the rocker touch the valve spring retainer. If it seems the valve stem tip does not protrude far enough past the keepers or protrude high enough above the retainer, you may need to install lash caps to gain more stem height. If the tops of the valves have really had a lot of meat ground off them, you may need new valves. You must be careful that the lash caps are not pressing on the tops of the keepers. Once all the pieces have been final-assembled, the valve lash can be adjusted in the normal fashion. This has worked for me on many big block Mopars, Hemi's, and Chevys.

 

[Wietse]

Get the longest length of push rod as you can, once you know the final length order them from Smith Brothers.
As MoparMur already mentioned, get some adjustable push rods to measure it.
Not sure how your pushrod oiling is done, but if it is not an oil-through type you are going for you need to check in the rocker arm.
There is an oiling hole that drips oil on the ball-cup of the push rod on the rocker arm side, the angle required to get oil in there needs to be determined to avoid lack of lubrication.
Going for, say only 2 threads below the rocker arm might not get oil in the cup where 4 threads might.
But you need to minimize the threads below the rocker to a minimum, an excessive long stud below the rocker could break, especially if the geometry is not in the ball park.

 

[66Satellite47]

I say 3-4 threads is good. 2 threads may get you into cup contact zone, depending on the cup design. maybe.

 

[Beekeeper]

Thanks I’ll stick with 4 threads

BTW anyone need a brand new set of smith brothers pushrods? The first set I had cut were with the wrong lifter so now I have a set that I’ll never use.

 

[F4R/T]

Thanks fellas !

 

[IQ52]

I would think the number of threads showing would depend upon who made the rockers and what they recommend. I know of some big and small block rockers that would have NO threads showing when adjusted per the maker. IF they are Ray Barton rockers and IF he says 3-4 threads and IF we are all smarter than Ray Barton about the rockers he is using......let's change the thread adjustment to make us happy.

 

[Wietse]

Actually you could determine the best geometry position by checking the valve lift.
The longer the adjuster screw sticks out from below, the more of a "sideway" movement the push rod is going to make...which causes you to loose valve lift.
Dunno who's Ray Barton, but if he makes them i would follow his recommendations.
He's done the math already, just double check everything like interference etc.

 

[66Satellite47]

Actually you could determine the best geometry position by checking the valve lift.
The longer the adjuster screw sticks out from below, the more of a "sideway" movement the push rod is going to make...which causes you to loose valve lift.
Dunno who's Ray Barton, but if he makes them i would follow his recommendations.
He's done the math already, just double check everything like interference etc.

You should look up who Ray Barton is and what his credentials are.

 

[Wietse]

You should look up who Ray Barton is and what his credentials are.

Just checked out their website, these guys seems serious.
I don't know most of them famous guys as their names don't come across the pond, some here with a real interest and racers might though.

 

[Mike67]

I would think the number of threads showing would depend upon who made the rockers and what they recommend. I know of some big and small block rockers that would have NO threads showing when adjusted per the maker. IF they are Ray Barton rockers and IF he says 3-4 threads and IF we are all smarter than Ray Barton about the rockers he is using......let's change the thread adjustment to make us happy.

I think you and @PRHeads mentioned this in another thread , specifically the Comp Pro Magnum rockers. I beleive Duane stated those only require 1 full turn from the seated position for the oil band to be in the center of the boss on the rocker.
Also add the lifter preload to the overerall pushrod measurement for hydraulic lifters.

 

[Mike67]

https://www.forbbodiesonly.com/mopa...m-rockers-comp-1621-16.225898/#post-911988895

 

[IQ52]

Good question my small block is either eating the cam or my adjuster spit off again. I’ll measure valve travel in the am but I’m curious as I think 3-4 threads is all that is wanted.. I have old 273 rocker arms on mine.

I'll admit that it's been 47 years since I used any 273 rocker arms. With that in mind 4 threads showing seems excessive to me.

 

[Wietse]

With that in mind 4 threads showing seems excessive to me.

If the adjuster screw is a cup style i guess the threads are allowed to stick out a little further compared to a ball style, right?

 

[66Satellite47]

Just checked out their website, these guys seems serious.
I don't know most of them famous guys as their names don't come across the pond, some here with a real interest and racers might though.

FYI Ray Barton is one of THE Hemi guys for many decades. Knows his stuff.

 

[IQ52]

If the adjuster screw is a cup style i guess the threads are allowed to stick out a little further compared to a ball style, right?

That would be an incorrect guess with the cup style rockers that I have used. i.e. Comp Cams Pro Magnum.

 

[Wietse]

That would be an incorrect guess with the cup style rockers that I have used. i.e. Comp Cams Pro Magnum.

You are right on that, if picking the cup style for the right reason you keep it close.
If you had to go that way it means you made a mistake with push rod length.