does anybody know what causes this to happen to a pushrod?









i will probably replace the whole set just for peace of mind, and was wandering which is the best ones to get?

im thinking the tapered pushrods that c.b. performance sells, i know they are expensive. but if they are the best, then i think they may be worth it to keep this from happening again?

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Chris

I had something similar happen but it was the lifter that actually failed. The lifter cup reamed out and made a much larger hole..

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this happened on the rocker arm end of the pushrod

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Chris

You might want to pull your heads and check the valves.A guide might have gave out and the valve got into a bind.If it bent a valve you might also need to put a new guide in.I dont want to worry you but its better to be safe than sorry.

How much lift do you have .& Do you now if you had the .035 wall tude or the .065 tube . The better Scat & bugpack & cb are .065 & up 4140 & the cheaper ones are .035 & 4130. +Check for a stuck valve in the guide .

I would bet on valve float and/or improperly set up rocker geometry.It could also be coil bind. The way it is broken leads me to think there is alot of side load on the end of the pushrod.

its got a 110 cam with pauter 1.4 rockers, also i pulled the end out of the pushrod thats messed up and according to the micrometer it is .035 wall

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Chris

it has double valve springs and has been together for 4 or 5 year i believe so i doubt its coil bind, however i will check it

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Chris

Read where a manufacturer is making them out of mild steel and calling them chrome molly. Lot of stuff coming out of China.

does anybody have any input on the tapered pushrods from c.b. performance

also i just went out to the shop and checked to see if the valve was stuck and it didnt seem an harder to mash than the rest on that side, and not that it matters but it was the pushrod for the intake valve on #.4 cyl. that this happened to

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Chris

i also heard bugpack had a bad run of pushrods a while back, but im not sure what brand these are

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Chris

Run a good set of Autocraft tapered or Scat tapered pushrods, I am running Scat ones with the 110 cam with the Pauter rockers as well.

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how critical is the measurement of the pushrods?

the best i can get with a metal ruler is 11 5/16 - 11 3/8 in the inch system or 288mm in the metric system

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Chris

It has to be pretty dang close, it will need to be the same, if it is off just a hair, it could make the roller tip on the rockers touch the valve in a different spot when set on zero, you would want the roller tip to be in the exact center of the valve tip so the roller can roll back and forth both directions evenly to help keep the wear on the guides down and gives you full lift as much as possible as well. You will want to measure the length on the ends of the rod only, not with the rod ends. That's what I did when I bent mine 2 years ago and called Drew's to have new ones cut and pressed, you might as well go ahead and get the full set and have them cut to your specs, mine was perfect when I got them. You do not want to use a bandsaw or hacksaw to cut them if you are doing them yourself, it has to be done on a lathe or it will not be true. Give Brian at Drew's a shout and he can make it happen for you and he even has the good Scat ones in stock.

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If you can tell one spring is weaker you need to put new springs on .+ .035 pushrod on a fast ramp high lift cam turn the pushrods into pole vaults that can brake spring & valves.

If you can push the valves down by hand you need new springs.I say its floating the valves due to weak springs and that mismatched cam/rocker combo.Running ratio rockers on a cam not designed for it makes this problem even worse.

I believe the 110 cam install recommends that 1.25 ratio rockers should be the maximum to use. How long did it last with the 1.4s?

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I think I can, I think I can....

Cut them yourself.Get an Old stock vw push rod and cut about 1.5" out of the center. Put about a 3-4" piece of threaded rod in it with 2 nuts on it.Remove an easy to get to push rod tube.Now install it and adjust the rod while at valve TDC and make it just snug. Turn the motor and measure the full travel of your lift off of your retainer (on top of spring) .Now take the measurement and divide it in 1/2.Then turn motor til retainer is 1/2 way down usinbg the measurement and stop.Here comes the critical part. Adjust the homade tool with the nuts til the swivel foot and the valve stem center each other horizontally. Put a washer under the rocker pedestals if you need more swivel feet threads. Now that you have it right remove your tool and make all your new push rods the same length.Use a brake line tubing cutter to make the cuts perfect and cut SLOWLY so you make a smooth clean cut.Keep it oiled. Take 2 old lifters. Lay one on the bench face down, hole up..The new pack of push rods should have 1 head already on it.Have someone hold the rod head down in the old lifter. Oh, scrap the metal crud out of the tube with that triangle edger attached to the tubing cutter.Now tap the loose head on the top of the rod. Tap it left or right til its centered.It's nice to weld a small pipe on the side of the second lifter to look like a hammer.Now lay the "hole" side of the lifter on top off the head and drive it down by hammering down on the surface side of the lifter.All of this is on the computer some where. I read it back in the 70's while in my math class.I think the book I read was "How to hot rod a VW"The verticle alignment is important too.They need to be just slightly mis aligned to keep the valve rotating so the seats and valves can keep each other "seasoned", wear uniformly.Remember you are getting a few free horsepower per cylinder plus less valve guide wear.The difference between cam grinds is only in thousandths so now you can see how important wasting lift and duration is.Straighten me up if I said anything wrong or left out something.

its been together for 4 or 5 year to the best of my knowledge, however i believe it failed due to being only .035 wall or it could have been a weak push rod to begin with and finaly gave out

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Chris

i took one of the good ones to a friends dad that had a 12in. micrometer and they were 11.332" from tip to tip and that is only like .006" less than the 288mm i came up with using the metric ruler i had

so i guess i will be makeing a few calls tomorow

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Chris

what do you mean chad?

i thought you had to know the total length with the ends installed, at least thats the measurement you would get when using one of those "pushrod tools" to check for length on a new/unknown build

by the way this is the motor on ol' rwb so im pretty sure the ones in it are the "correct" length for the setup

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Chris

Been thinking what would cause this? It would take a lot of pressure on each end of rod to do that. One guess is a siezed lifter, but that would just hold the valve open. If push rods were wrong lenght and geometry off it could be valve guide wear and valve got bound and jambed. I think there's more to do than just replacing the rods. Good luck.

probably what happen is when they made up the push rod an pressed the end in it formed a hair line crack an got worse over time

im hoping thats something along the lines of what happened because i cant find anything else wrong , at least without starting it up (fingers crossed)

ive got a set of the thick walled scat pushrods on the way and supposed to be allready cut and be here thursday

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Chris

Either way will work, I think it will be more true if measured without the ends installed on them, I know that if you buy a set of un-cut ones that is not tapered, there will be one end already pressed on and the other end is blank and that is the end you cut, if buying a set of blank tapered rods, there will be no ends pressed on them at all, you will have to cut both ends evenly to keep the largest diameter part of the rod in the middle, not offset, sorry for the confusion If I am cutting them, that would be they way I will measure them and make sure the ends are exactly the same, some may be made differently.

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