Valve clearance with Al pushrods .1 or .15mm (.004" or .006") ?

[Martin S.]

I have the straight aluminum pushrods in my engine and wondering what clearance is best. Berg used to recommend a combo when using their cromo pushrods.  004 or 006?

[Fiatdude]

I've always set my Aluminum pushrods at zero lash

Chromalloy is set at 4 and 6

[DaveN]

I've always set my Aluminum pushrods at zero lash

Chromalloy is set at 4 and 6

Are you sure ? I thought aluminium expanded quicker than chromoly

[Martin S.]

The other option is zero lash, of course. I thought that was for cromoly because they didn't expand at the same rate as aluminum. Stock is .004" or .006" depending on what year.

[baz]

I'm sure I read that it depends on Alu or Mag case too.

I'd be interested in hearing more too, I'm using Alu rods with Alu case

[RhoadsVW]

Aluminum  .004   Chromoly set at zero lash

[Fiatdude]

I have to admit that it has been 25 years since I ran Chromalloy push rods so I could be very wrong in my answer for them......

Easiest way to make sure whatever you're doing is correct is to warm up the engine and then while it is hot check your lash, you want just a slight (.0005) clearance at operating temp. -- -- it's is a little messy but it takes all the guess work out of it -- I watched the Baron get it's lash set and they set it to zero then add additional 1/2 turn --

It all depends on all the different pieces in your puzzle.... With my dual tapper AL push rods, ARPM Case, tool steel lifters, Pauter rockers and 600# springs, I was at zero lash cold.

[neil68]

I ran my aluminum pushrods at 0.002-3" with a mag case.  Will start with loose zero with aluminum case and then check lash at operating temperature.

[baz]

I ran my aluminum pushrods at 0.002-3" with a mag case.  Will start with loose zero with aluminum case and then check lash at operating temperature.

Thanks Neil, was sure I read this somewhere previously.

[Martin S.]

What do we look for when checking running (hot) valve lash? I haven't tried that before.

[bedjo78]

Al pushrod ..  0 + 1/4 turn on wbx case

[bedjo78]

I have to admit that it has been 25 years since I ran Chromalloy push rods so I could be very wrong in my answer for them......

Easiest way to make sure whatever you're doing is correct is to warm up the engine and then while it is hot check your lash, you want just a slight (.0005) clearance at operating temp. -- -- it's is a little messy but it takes all the guess work out of it -- I watched the Baron get it's lash set and they set it to zero then add additional 1/2 turn --

It all depends on all the different pieces in your puzzle.... With my dual tapper AL push rods, ARPM Case, tool steel lifters, Pauter rockers and 600# springs, I was at zero lash cold.

Interesting. What Aluminim push rod  do you run with 600 lbs on nose ? I have run it 500lbs . But now I want to change rockers that would whoop up springs to 560 lbs.  But I am too worry if is it hold up 8000 rpm

[Fiatdude]

I have to admit that it has been 25 years since I ran Chromalloy push rods so I could be very wrong in my answer for them......

Easiest way to make sure whatever you're doing is correct is to warm up the engine and then while it is hot check your lash, you want just a slight (.0005) clearance at operating temp. -- -- it's is a little messy but it takes all the guess work out of it -- I watched the Baron get it's lash set and they set it to zero then add additional 1/2 turn --

It all depends on all the different pieces in your puzzle.... With my dual tapper AL push rods, ARPM Case, tool steel lifters, Pauter rockers and 600# springs, I was at zero lash cold.

Interesting. What Aluminim push rod  do you run with 600 lbs on nose ? I have run it 500lbs . But now I want to change rockers that would whoop up springs to 560 lbs.  But I am too worry if is it hold up 8000 rpm

I was recommended some dual tapper ones (3/8" diameter) by Scott Featheroff and I can't for the life of me remember where I got them from -- might be listed in my Karman Sutra thread....

I ended up breaking a lot of rocker arm studs and gave up on those springs and switched to some NASCAR beehive springs (rated at less pounds but behaved like the big boys).... Scott has a lot higher rated springs in the Baron, but they break rockers regularly.... There is always a weak link LOL

[Dougy Dee]

Al pushrod ..  0 + 1/4 turn on wbx case

That would be .010/.25mm.

I use the flats or points on the adjuster nut. 1 point is a heavy .006/.15mm.

Street motor with stock case and CroMo pushrods I set up with  4 to  6 thou lash. Leaves the ex valve on the seat longer to aid in ex valve cooling.

[Jim Ratto]

Al pushrod ..  0 + 1/4 turn on wbx case

That would be .010/.25mm.

I use the flats or points on the adjuster nut. 1 point is a heavy .006/.15mm.

Street motor with stock case and CroMo pushrods I set up with  4 to  6 thou lash. Leaves the ex valve on the seat longer to aid in ex valve cooling.

Me too, though I run mine @ 0.003"- for same reason as yours, and my car idles and responds to throttle crisper with lash.

[Martin S.]

I'm a little surprised at people still using cromo pushrods. Nice not to hear the clatter of them, although I guess some may like the sound?

[Clatter]

Some interesting theories here.. Been geeking out on this for years.

.004 intake and .006 exhaust is SOP for aluminum (or .006 .006).

Best thing about steel pushrods is you run them at zero.
Makes for a quieter motor at cold-start than that .004 or .006 with aluminum..
(Plus you don't give away those critical thou of lift!)

If your steel pushrods make noise hot when set at zero cold, you are overheating IMHO.

Also love setting lash at zero, as no feeler needed.
But,
Yes,
By now an old man can set them at .004 or .006 by feel..

Ideally,
You check them at 100% hottest running temp, and work it out so they are at zero when hot hot,
Regardless of material.
Whatever that setting happens to be cold is immaterial, and is what it is, and you set them there...

If that makes any sense...

Said another way,
After you get to know your motor, and check them hot,
You can learn to set them cold so they are at zero when hot.

[Torben Alstrup]

Depends on how precise the cam is ground. Safe in every circumstance, use stock clearances.
Engle cams in general and actually also CB cams. 0,05 mm
Raptor, Web cams, loose zero.

[Taylor]

Some interesting theories here.. Been geeking out on this for years.

.004 intake and .006 exhaust is SOP for aluminum (or .006 .006).

Best thing about steel pushrods is you run them at zero.
Makes for a quieter motor at cold-start than that .004 or .006 with aluminum..
(Plus you don't give away those critical thou of lift!)

If your steel pushrods make noise hot when set at zero cold, you are overheating IMHO.

Also love setting lash at zero, as no feeler needed.
But,
Yes,
By now an old man can set them at .004 or .006 by feel..

Ideally,
You check them at 100% hottest running temp, and work it out so they are at zero when hot hot,
Regardless of material.
Whatever that setting happens to be cold is immaterial, and is what it is, and you set them there...

If that makes any sense...

Said another way,
After you get to know your motor, and check them hot,
You can learn to set them cold so they are at zero when hot.

Good luck getting your motor to start with the valves open .030"!

[Martin S.]

Everyone knows what happens to your power and compression when the valves are set too tight. I don't see a problem with them set on the loose side, except for the noise. Since I started using aluminum pushrods instead of steel, the valve train is much quieter even with some clearance.

[bedjo78]

Is it excessive valve gap bouncing the pushrod tips alot causing to fail?

[Jim Ratto]

I ran Aircooled.net aluminum pushrods for 15 years in my car, against the now NLA Bugpack 4046 springs, and ran my lash @ 0.004".
In 2015, after Bugpack was no more, and the last few sets of springs I had were sold off, and my 2165 was apart, I switched to CB VW650, same cam, rockers, etc. So I re-installed the AC aluminum pushrods. Same lash: 0.004".
In short order, I noticed a little more thrash from valvetrain. Not something I ignore and let slide, so I pulled rockers off to check for lash cap issues, or scuffer pad issues (my rockers were bought new in 1991 and have been run since). Nothing was wrong with either, but what I did find was the ends of the pushrods were beginning to pound into the aluminum. This was immediately after upping spring pressure. So I've gone back to Berg (like I ran in the 90's) and valve lash is staying put. I don't, personally, like the idea of running a normally-driven street air-cooled engine with no lash. With mine set @ 0.002", I do not find the valve train noise, once warm, to be offensive or excessive. I've tried the zero lash thing, with the Berg, and the car idles poorly when cold, and isn't as crisp when warm, which may indicate a little too much cam for my car- if I wanted to set my lash @ 0.00"

[Martin S.]

Interesting. Steve said he was really happy I got the AC net aluminum pushrods as he hates valve train noise, being more of a rotary motor guy. He said the pushrods from AC net are made by Smith Bros. and the reason that they are as good as they are is that they grind them straight rather than rely on the extrusion being straight. If they are perfectly straight, out of the box he said, they won't fail as easily. So far mine have been rock solid requiring very minimal adjustment.

[bedjo78]

has anyone run straight aluminum pushrod from aircooled.net , say with 400lbs on nose as per their claim?

[Pedalpusher]

Jim Ratto, were your ACnet aluminum pushrods the straight or dual tapered style when running those bugpack springs?

bedjo78, I'm about to try those straight ones this summer when I get my engine back together in a couple of weeks. Or actually they're not ACnet straights but stateside tuning ones I got to test. They are grind straight so I'm hopeful they will work as I have C55 cam, 1,25rockers and scat super D-ports with the original scat dual springs.

-Mikko-

[Jim Ratto]

Jim Ratto, were your ACnet aluminum pushrods the straight or dual tapered style when running those bugpack springs?

bedjo78, I'm about to try those straight ones this summer when I get my engine back together in a couple of weeks. Or actually they're not ACnet straights but stateside tuning ones I got to test. They are grind straight so I'm hopeful they will work as I have C55 cam, 1,25rockers and scat super D-ports with the original scat dual springs.

-Mikko-

Straight.

the 4046 gave around 320lb over the nose when new and around 165-170 @ the seat.

[Martin S.]

Thanks for making me re-read John's info about my pushrods. He says to use .006" cold which will be .002" hot. I didn't know about that. Also his info about tips pounding in could relate to Jim's experience:

"Valve lash is critical on aluminum pushrods. It is possible to have a pushrod failure even though you haven't exceeded our RPM or spring pressure limits, and this is always due to excessive valve lash. If your valve lash gets over .010", the tips of the pushrods WILL get pounded into the pushrod. This is not a problem if your valve clearance is the way it's supposed to be, but a swivel foot failure, or loose valve adjusting screw, can cause excessive lash which can ruin these pushrods quickly. "

https://vwparts.aircooled.net/ACN-Heavy-Duty-Aluminum-Pushrods-Set-of-8-p/acnhdalpr.htm

[Jim Ratto]

Thanks for making me re-read John's info about my pushrods. He says to use .006" cold which will be .002" hot. I didn't know about that. Also his info about tips pounding in could relate to Jim's experience:

"Valve lash is critical on aluminum pushrods. It is possible to have a pushrod failure even though you haven't exceeded our RPM or spring pressure limits, and this is always due to excessive valve lash. If your valve lash gets over .010", the tips of the pushrods WILL get pounded into the pushrod. This is not a problem if your valve clearance is the way it's supposed to be, but a swivel foot failure, or loose valve adjusting screw, can cause excessive lash which can ruin these pushrods quickly. "

https://vwparts.aircooled.net/ACN-Heavy-Duty-Aluminum-Pushrods-Set-of-8-p/acnhdalpr.htm

my issue was related to increase in spring pressure. Until then I had no issues with them.

[Martin S.]

Yes I read that and it contradicts what John said, which is interesting. I don't want that to happen to me so I'm open to anyone's opinion and experiences.

[Pedalpusher]

So I have now installed the grind straight aluminum pushrods, which I even updated with oil sprinkler holes alá Ray Vallero on the intake rods.
I set lash .10mm/.004" cold and seems good. I ran a 25km test drive and thought the next day that the parts would now be settled in their places better and checked the lash again. It hadn't changed at all.
Will be looking for to test them further with some whipping and running harder.

-Mikko-