Chromoly pushrods

[Motor60]

Can anyone explain how to adjust valves with chromoly pushrods and roller rockers? I know it's 0 lash but they keep getting loose somehow. I'll tighten them up but after a few rides they get noisy. Someone explained once I get 0 lash the pushrods should have some resistance if I tried to spin it. Is that true?

[mark tucker]

first do you knoe how to properly adjust the valves??? if so then you may have other issues.

[Motor60]

Yes, I was setting them to zero lash, by hand, then tightening the nut...But as i read on, I guess chromoly doesnt stretch like aluminum...So if i understand correctly, they are going to be noisy regardless...

However, I drove it to work and everything was fine...but when i drove it home, the valve train was very noisy, sounded like a bad exhaust leak, and the motor idled crappy....I pulled the plug wires off the dizzy cap, one at a time, just to check if all cylinders were firing..And they were...the only thing i didnt do was blow out the idle jets...

i'll have to backtrack a bit....the valve train was noisy, so I checked the play..and noticed the #1 cylinder valves were extremely loose. I tightened them up (cold engine) zero lash...and the intake valve for the #4 cylinder as a tad loose...all others were zero lash....fired it up, valve train nice and quiet and motor purrred...Until I drove it home, in 90 degree weather, and it started idling rough in traffic, and sounded like a bad exhaust leak

[Motor60]

i set crank pulley at TDC for the #1 cylinder....I set both intake and exhaust valves at zero lash....Turn the crank pulley counter clockwise and adjust the #2 cylinder....and so on...

All set to zero lash...

NOW, someone explained that when the pulley is at TDC, they valve is not totally closed because the cam is not completely pointing at the #4 cylinder....so i was instructed to start with the #1 exhaust valve...turn the crank pulley and watch the #4 exhaust valve until i see that its COMPLETELY open....that means the #1 exhaust valve should be COMPLETELY closed...and THATS where i should set the valve to zero lash...then did the #1 intake valve the same way, where the #4 intake valve was fully open...and so on...

Well i tried that, and it didnt really make much difference, actually sounded very loud. so i went back to TDC, re-adjusted (after engine was cool), and valves were quiet...even when the motor was warm. Has anyone heard of adjusting them like that? I found that i would be setting the valves at 70* ATDC.

[jsturtlebuggy]

Looking at what wrote about adjusting #1 while #4 exhaust was open, I not sure if you actually mean #3 exhaust which shares the same cam lobe as #1
Cylinders #2 & #4 share the same cam lobes.
Unless you have cam that has a lot of duration, just adjusting valve on each cylinder when on compression stroke at TDC should work ok.
Noise can also be cause by too much side play in rocker arms.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

[mark tucker]

so... you need to know how to adjust valves. do them one at a time . dont worry about where the pully is or any timing marks or the phase of the moon. when an exhaust starts to open ,when it is about 1/8~1/4" open you then adjust the intake valve next to it on the same cylinder to zero lash. zero is zero not loose not tight but zero. then turn the crank in running direction only!!!(I turn my crank by the alt pully nut). turn the crank untill an intake go's down then comes back up,stop when the intake valve is about 1/4~1/8" from closing. then you adjust the exhaust valve next to that intake valve on the same cylinder. repeat this on all 4 cylinders. also be sure to pull the rocker rearward when adjusting,the rocker is thrusted rearward so it needs to be rearward when adjusting.(unless you have a mid engine car). if you still have an issue your cam or rockers or pushrods are dieing and the oil is probably filled with debris.

[Motor60]

[Motor7710]

I had the same problem your describing so I'm
just curious... are you running with really light but thin chromoly pushrod tubes with dual springs?
If you are, you might want to check your pushrod tubes on both ends and look for any evidence of shrinkage or collapse. I know.. seeing is believing! Heres some pics.
The one the right is the new thicker but heavier chromoly pushrod tube. On the left, the thin but light pushrod tubes ends have shrunk and mushroomed.

Her you can see how much it shrunk compared to the new ones.

_________________
If it stopped dripping oil you’re probably out of oil!

[mark tucker]

yup there are thin .038 wall and thicker ones(.053, .058 and even thicker avaliable,hell some v8 racing pushrods are more than 7/16" wall thickness.)
I have a few sets of the thin wall and the tubing is fine but the tips varry around .006" so.....some are tight and some are snug.....(read as loose after run) I have never had any issue with the loose ones,I have gone through tips and installed the right size tips in the pushrods that had the loose tips in them and there just fine. Ive never mushroomed any.loose lash can mushroom them, valve float can mushroom them, detonation can mushroom them.dead cam can do it, dead springs can do it too. rocker/pushrod interfearance can also do it. so.....find your issue and fix it.it's just a prosess of elmination.kinda like a wife or bank account. yes I love my wife and she handles the bank account...and I just got a pile of new machine tooling.. and...ordered more today....she's a good one.
the empi black ones are famous for tips that are not sized good, but Ive had other name brands the same. the cb silver ones(.058 I think) have always been perfectly sized as far as I know. and there about $10 more.

[Motor60]

I've never built a motor so this is new to me...to pull the pushrods out, do i have to remove the rocker arms? Just the two nuts removed? Or how do I remove the PR's ??? to check for mushroom..

[mark tucker]

pull rockers. you can then also check the rockers to see if there dead on the shafts. and be sure to use a torque wrench to reinstall them
.

[Motor60]

Is it just the 2 nuts to remove the rockers? And what is the torque to put them back??

[slalombuggy]

Yes the 2 nuts hold the rockers on. Torque is 18ft/lbs

brad

[Scott Novak]

Also be wary that some chromoly push rods may not actually be made of chromoly. It's buyer beware when buying aftermarket parts.

Years ago I tried some fairly thick wall aluminum pushrod tubes. They crushed inward just like the thin wall Chromoly tube above did.

I have heard that they new aluminum pushrod tubes are supposed to be much better in quality, with a better alloy and heat treatment.

I've been using Gene Berg 0.035" wall Chromoly pushrod tubes for 25,000 miles and haven't seen any problems with them. After the valve job I set them for 0.004" valve lash during the break in of the valves and piston rings. Now I've reset them back to a loose zero.

For me a loose zero is just tight enough so that at TDC, I can spin the pushrods with my fingers, without any noticeable valve lash when the engine is cold.

Scott Novak

[Motor60]

yes there is excessive side play. Between .015-.017" using feeler gauge. That's prob noise I'm hearing. Cuz there was no lash still. I removed the shafts and only one pushrod is slightly shorter. Cuz of mushroom. Soooo do I have to replace that one pushrod or all of them to be same? Im buying shims to make this right. Now I've read about side play
.005-.006. And I've read .003
Anyone have a definite answer?
And I have roller rockers. So do I put the roller center with lash cap?

[Scott Novak]

If you had one pushrod mushroom it's a good sign that they are inadequate for your engine. You need either a heavier or better quality pushrod.

You should also take the time to double check that your rocker arm geometry is correct. You always adjust the rocker arm geometry first and then cut the pushrods to fit.

Scott Novak

[mark tucker]

I like around .004~.006 on intake and around.006~.008 on exhaust for side clearance. the head will grow more than the shaft so the intakes will loosen when hot and the exhaust will get tighter side clearances. and use thick shims agnist the rocker.if thin shim is needed put it between thicker ones. try to have atleast 2 shims on the thrust side of the rocker( I like 3 shims on thrust side)(thrust side is rear side of all rockers,tward rear bumper of car) pay attn to push rod to pushrod tube clearance so your tubes dont get eaten up. also the pushrods need a flat on the end where the hole is.

[Motor60]

This is all new to me. I've never worked on valve train. So, how long should my pushrods be? How do I know if they are too long or too short? And what do you mean they should have a flat??? Flat what? They have tips on both sides

[Motor60]

The intake pushrod of #2 cylinder looked like it was resting against the pushrod tube. All the others looked like they were centered or slight off centered in the hole of the head. I'm not a VW genius but it doesn't look right. What does that mean. Or how do I fix that

I have a 2054 motor. 74x94
1.25 rockers

So how long should my pushrods be? Or are they stock length? I'm for sure gonna need one. But I will replace them if they are not good chromoly. Was thinking of Gene Berg rods but need to know correct length.

[mark tucker]

what rockers?? you can shim the rocker over a little for added clearance, or get big mouth pushrod tubes. the flat is on the end at the oil hole.the end does not need to support any load, if the raidi/size is off a little the hole can sheer off /gauld/deform some material from the rocker cup. I add about a .080"~.100" flat with the hole in the center using a belt sander then deburr the hole&flush the pushrods clean.

you may need to go back and set the geo to figure the pushrod length there are many post on it.if your just changing one pushrod then just make it the same as the others.