[wakesupremo]

When setting the valve lash with a hydraulic roller cam and cold engine, should there be 'play' in the pushrod or should the pushrod be able to be turned by fingers but no 'play'?

[25stevem]

Do you have Aluminum heads?

Are the push rod plungers in your lifters held in with a round clip, or a square sided clip?

[78w72]

Originally Posted by wakesupremo

When setting the valve lash with a hydraulic roller cam and cold engine, should there be 'play' in the pushrod or should the pushrod be able to be turned by fingers but no 'play'?

"zero lash" means no play up/down on the push rod, but should still be able to just turn it with fingers, any more youre adding preload.

then follow lifter manufacturer recommended turns of the nut to set preload, each type/brand of lifter can have different preload setting. or try cliffs suggestion of bottoming out the lifter then backing off 1 turn.

[Schurkey]

Guys get into trouble because it's often possible to "turn" (or "spin") the pushrod long after zero-lash has been achieved. If the pushrod isn't oily and you have strong fingers, you can maybe spin the pushrod after the lifter plunger has collapsed. Then they add a half-turn of "preload" and the valve won't shut.

Then they post on the forum that the engine won't start, or starts but runs poorly/roughly. Worst-case, they wipe the cam lobe(s) and lifter bottom(s) during cam break-in.

My advice is DON'T TURN/SPIN THE PUSHROD to feel for zero lash. Lift up 'n' down on the rocker arm instead. As you tighten the adjuster, the free motion reduces. When the rocker is just at the point where it won't move freely (has to be forced to move) you're at zero lash.

[wakesupremo]

Thanks again for the info. I'm not sure about the round clip or square clip. They are Johnson lifters with scorpion 1.65 roller rockers. I can very slightly lift the rockers off the ball of the pushrod. I mean by the minutest of a fraction. of movement but, none the less they do come 'loose'.

[25stevem]

Just the talk or use of the word lash when dealing with a hydro lifter is wrong for a true street motor and that shows you don't understand the reason for running Hydro lifters in the first place.

Sorry if I have stepped on any Toe's but such is the truth at times.

Please answer if you have iron or Aluminum heads and you will get a far better detailed reply.

[chiphead]

Semantics. It's lash for solid lifter and preload for hyd lifter.
I agree with Schurkey on the spin thing. It's the up and down of the pushrod that shows when the slack has been taken out of a hyd valvetrain. For me, I jiggle the pushrod up and down slightly while SLOWLY adjusting the polylock tighter. At the moment there is no more jiggle, STOP.
The slack is out and you're ready to start adding preload by turning the polylock an additional 1/2 to 1 turn.

[Schurkey]

It's "lash" for hydraulic and solid lifters UNTIL you pass the "zero-lash" point with Hydraulics. Then it's "lifter preload". (When you pass the "zero lash" point with solid lifters, it's called "engine doesn't run right, valves don't close properly".)

With hydraulic lifters, getting to the zero lash point is the tricky part. Any monkey can add a measured amount of preload AFTER the hard part (finding zero lash) is accomplished.

One of several advantages to using aftermarket "polylocks" is that it makes finding the zero lash point heaps easier. With little friction between the nut and the stud threads, a person can just spin the nut down with their fingers and "feel" for the increased resistance when the lifter plunger starts to collapse. (Of course, the lifter being adjusted would have to be on the base-circle of the cam.)

You'd better have some experience with setting lifter preload before you try to use Cliff Ruggle's suggestion of going "up" from the point where the lifter plunger is bottomed, instead of the usual procedure where you go "down" from zero lash.

[78w72]

some may be overthinking the turning of the pushrod after zero lash. if you have a good sense of how the p/r feels while spinning it with lash before the nut is tightened to zero lash, its pretty easy to tell when there just starts to be drag on turning it due to the "lash" being taken up. but as stated, its more about feeling up/down play.

why does the material of the heads matter for reaching initial zero lash? because alum expands more than iron you may want to add a little more preload to compensate for that but not sure why the head material matters for reaching initial zero lash.

with all the talk about variances in stud thread pitch i doubt turning the rocker nut 2-3 degrees past true zero lash will make much of a difference in the overall adjustment of the lifter or making the valve not shut. heck some guys dont even pay attention to the lifter manufacturer recommended adjustment, they just tighten them down 1/2 to 1 full turn not caring much about what the correct setting is for the brand of lifter being used. or adjusting them with the engine running till the ticking stops.

[wakesupremo]

Thanks again for the replys albeit that some are a bit harsh!! They're alluminium Kaufmann heads. Also the car is regularly raced so not really a 'street' motor. In UK our standards are much stricter as to what becomes a 'street' motor!

[25stevem]

Thank you for the info on the heads your running!

Now details that suit your motor / usage best can be talked about.

Your heads and valvetrainwill grow taller by up to .008" when they have got up to normal operation temperature.
If you're looking to not be rpm limited by hydraulic lifter pump up then you should set your lifter preload at a mire 012".

When the motor is then up to normal temp you should then be darn close to zero preload and in effect have the nature of a solid lifter roller Cam.

[wakesupremo]

Thank you again. Please let me explain my circumstance and the reason for my questions. Whilst talking in the pit area during a racing weekend a couple of years ago, a good friend that builds his own racing engines, albeit that they're fords!!, told me that he wanted to make my car, a fully road legal, street trimmed including all interior trim etc 1969 firebird convertible , run in the 11 sec zone. He was told in no uncertain terms that this wasn't possible. However, the journey began. I ordered parts from Tin Indian Performance to a specific recipe. During this time there was a couple of 'confusion issues' whereby the builder asked for certain items but I was told, very nicely, by Kevin and the T.I.P. staff that they weren't necessary. As the engine builder specified these parts I went along with what he asked.Therefore there are a couple of things that he wasn't 'pontiac wise' to including the need for PCV and setting the valve lash or preload whichever you prefer. He set them as he would his fords but, none of his are road vehicles, purely race. This is where the slight differences occur. However, with his engine, at a great cost to me, the car has run a best of 11.40 @ 125mph so he achieved his goal. The dyno run proved it at 600HP @ 5800 RPM and 600 ft lb torque at 4800 RPM.
I hope this clears up a few issues and stops people thinking that I'm playing with stuff I don't understand. I just have a busy mind and a non Pontiac wise engine builder!!!! Thanks all for the information given.

[ta man]

Originally Posted by wakesupremo

Thank you again. Please let me explain my circumstance and the reason for my questions. Whilst talking in the pit area during a racing weekend a couple of years ago, a good friend that builds his own racing engines, albeit that they're fords!!, told me that he wanted to make my car, a fully road legal, street trimmed including all interior trim etc 1969 firebird convertible , run in the 11 sec zone. He was told in no uncertain terms that this wasn't possible. However, the journey began. I ordered parts from Tin Indian Performance to a specific recipe. During this time there was a couple of 'confusion issues' whereby the builder asked for certain items but I was told, very nicely, by Kevin and the T.I.P. staff that they weren't necessary. As the engine builder specified these parts I went along with what he asked.Therefore there are a couple of things that he wasn't 'pontiac wise' to including the need for PCV and setting the valve lash or preload whichever you prefer. He set them as he would his fords but, none of his are road vehicles, purely race. This is where the slight differences occur. However, with his engine, at a great cost to me, the car has run a best of 11.40 @ 125mph so he achieved his goal. The dyno run proved it at 600HP @ 5800 RPM and 600 ft lb torque at 4800 RPM.
I hope this clears up a few issues and stops people thinking that I'm playing with stuff I don't understand. I just have a busy mind and a non Pontiac wise engine builder!!!! Thanks all for the information given.

125mph is stout for a street car!..Must be soft leaving or traction issues? High tens or quicker with a good launch sounds like a great build.

[wakesupremo]

Thanks again. i think I have torque converter slip but not sure how to measure it!!!! 1.4 60ft times. Its definitely no slouch!!!

[461-69bird]

Gary, there's a calculator on Wallace racing site, you can work it out.
Have you got Caltracs now? that's a much better 60ft than mine

[AG]

Originally Posted by wakesupremo

Thanks again. i think I have torque converter slip but not sure how to measure it!!!! 1.4 60ft times. Its definitely no slouch!!!

Post your exact mph, your tire diameter and your rear end ratio.

[Formulajones]

Originally Posted by wakesupremo

there are a couple of things that he wasn't 'pontiac wise' to including the need for PCV and setting the valve lash or preload whichever you prefer. He set them as he would his fords but, none of his are road vehicles, purely race. This is where the slight differences occur. .

Honestly it really shouldn't matter. Preload is preload for the specific hydraulic lifter used no matter what engine brand. If done correctly it will work as intended.

I do very much as described already. Lobe on base circle, I check for play as I slowly rotate the poly lock. You'll feel tension on the poly lock as you turn it and reach zero lash.

From there set preload per lifter manufacture and you're done. Most normal travel lifters call for .030-.040" so there is a range, it's not super precise. Where people get into trouble is not taking into account the thread pitch on the stud used and/or cylinder head material, rocker ratio, and just assume a 1/2 turn will do it because that's what is regurgitated everywhere.

On a typical 7/16-20 stud a half turn is only .025". That's not enough. When an aluminum cylinder head is used I add another .010" to the recommended preload. So on a 7/16-20 stud I usually end up beyond 3/4 of a turn, which sounds like a lot to some, but in all actuality it's not.
To be certain I set up a dial indicator on the first one to make sure I'm getting there, then adjust the rest the same.

If you used a short travel lifter then the preload changes but the procedure is the same. It helps to know the specific brand and part number used to give any guidance.

[wakesupremo]

Once again, brilliant knowledge, thank you. The lifters are Johnson ST 21120 PR. It says on them 0.030 preload +/- .005.

[Formulajones]

Originally Posted by wakesupremo

Once again, brilliant knowledge, thank you. The lifters are Johnson ST 21120 PR. It says on them 0.030 preload +/- .005.

I'll take a guess that chances are good you're running a 7/16-20 stud as that's super common on builds these days. You'll end up just past a 1/2 turn for that preload, maybe a pinch more if you want to compensate for aluminum heads.

As a reference, 3/4 turn should be roughly ~.037" on a 7/16-20 stud.

[wakesupremo]

Thanks again for the info.