Pushrods control.

[j-f]

How do you check if your pushrods are still in good shape?
I was setting valves on my engine and was curious about checking if the stock pushrods where still straight. (And re set some very lousy rockers  )

Some people roll them on a glass window but as VW tolerances are 0.30mm out of roundness, it is really hard to estimate if they are still good for duty.

So I check them in a lathe with a dial indicator. But I wonder where I should take measures? In the middle or at the end?

[j-f]

And 3 of the pushrods ends look like this.

What did I wrong? Over revving? Valve float? Wrong valve train setting? It's a 1600cc, VZ14, single HD springs. Never go further than 5.500rpm and 3500rpm on the highway.

[Lee.C]

Hmmm interesting dude - as for checking the "straightness" of your pushrods rolliing them on a good think sheet of glass should be fine, but if you do want to use the lathe then I would suggest surrporting the loose end of the pushrod as you will NEVER get an acurate reading other wise 

As for the "Damaged" pushrods - That is EXACTLY what happened to mine in the Manx when I raised the CR (check out my thread) now this was due to INCORRECT pushrod length meaning that the "cup" on the rocker arm came into contact with the pushrod when the valve was fully open AND fully closed - I hope that makes sence 

Drop me a PM if you need any more info dude 

[j-f]

Hi Lee,

I have the heads 1mm flycut. But I grind the rockers to have more space beside the adjusting screw (swivel feet) and add spacers to adjust valve geometry. I turn the engine by hand to check if all was ok and didn't notice anything wrong 
But as it my first full engine build, I may have made some errors. (Experience is the name we give to our mistakes  )

And you are right for the pushrods fixture, it bent slightly just by supporting the dial indicator  But where is the good place to measure it? In the middle (that's what I think) or at the end?

[Nico86]

To measure the correct length you need for your push rod you can buy a tool made for that, or make one with an old pushrod (but the old pushrod you will use have to be straight too) : http://www.geneberg.com/cat.php?cPath=6_212&osCsid=f93010f24b785d984

[j-f]

To measure the correct length you need for your push rod you can buy a tool made for that, or make one with an old pushrod (but the old pushrod you will use have to be straight too) : http://www.geneberg.com/cat.php?cPath=6_212&osCsid=f93010f24b785d984

I already did one 

[j-f]

Problem is different from what I thought. Pushrods are getting crush.

[Lee.C]

Problem is different from what I thought. Pushrods are getting crush.

From my experience (which I mentioned) this looks very much like INCORRECT rocker geometry - Remember that the pushrod length needs to be set at HALF LIFT

PM me if you need any more tips dude 

[j-f]

Problem is different from what I thought. Pushrods are getting crush.

From my experience (which I mentioned) this looks very much like INCORRECT rocker geometry - Remember that the pushrod length needs to be set at HALF LIFT

PM me if you need any more tips dude 

That's how I did buddy. Or at least I thought it was correctly done 
I use a dial indicator to put valves at half lift and I use a home made adjustable pushrod to have the valve and the rocker screw align. In this case, I only needed to shims the rocker assembly with the stock pushrods.
I will try HD alu pushrods and reset the whole mess.

[nicolas]

hey,

maybe not the greatest help on the subject, but there was no 'real' difference in geometry when i flycut my heads. i fact it lined up better then before. But you also have the swivel feet to take into acount those make a bigger difference. the good news is that you can adjust the swivelfeet, so a difference of 1-2 mm is possible (correct is always better) you only need to make sure the rockers get oil from the hole in the swivel.
the problem is from what i think your pushrods. they are aluminium and will not stand too much abuse from the vz 14 cam. valvefloat may have helped as well.
and like lee said the lathe is of no use with that setup. you need at least a centerpoint. and what about the tollerance of the tube itself. they are cu from a tube and not machined round, so there is almost always some difference. the glassrolling is easy and accurate enough for what you need to find out.

[j-f]

I come back with my valve train problems. 

I re did the valve train geometry from the beginning.

And this is what I end up with.

#1 pics is fully closed.
#2 is half lift.
#3 is fully depressed.

Am I in the good way?

[Lee.C]

Well yo my "Ammature" eyes that looks Perfect dude 

[j-f]

Well yo my "Ammature" eyes that looks Perfect dude 

Thanks Buddy 

I took a closer on how the valve train work. And some of my pushrods tips come close to the cup of the rockers when valve is closed. There is some slight height differences between valve stem.
So I think my problems come from valve float 


 

[DKK Ted]

Looks good to me!!

Ted