I just had a conversation with my friend, and he said that to get that maximum stroke out of the 1.6 RR's I need to get 100 long pushrods. What the *beep* does that mean? I think I'm going to go with a 7/16 diameter, but what does 100 long mean? Can you help? :confused: :bb

 

I'm not scorp but I think he might mean you need to find the correct length pushrod, then add .100 length to that for preload. Everyone you talk to says something different when your talking valve geometery. I used the exact lenth that I measured, per some of the more knowledgeable members running the same setup I was.

Hope this helped. I would get some clarification from whoever told you just to make sure.

Just has a sidenote:

My pushrods needed to be 7.200". He is saying if you measure them to the 7.200 then add .100 for preload.

:cheers:


[Modified by ski_dwn_it, 10:08 AM 10/1/2002]

 

...(Scoffing remark removed by popular demand)... :D


[Modified by Rich B., 9:15 PM 10/3/2002]

 

:eek: :eek: :rolleyes:

 

:jester

 

TTT for you

 

...Scorp must be busy...Maybe someone else will jump in... :flag

(Remarks edited due to popular demand)


[Modified by Rich B., 9:17 PM 10/3/2002]

 

Thanks ski for a worthwhile response. Adoring public? Scorp actually puts effort into helping other forum members out with everything. I witnessed him actually do math for another member. I'd say that by far, he's helped me the most with anything and everything about my car, that has to count for something. :yesnod:

There are some people that are just great at being there for others. And he doesn't even know me. I'm just some high school kid. Not many adults put up with kids. I'm appreciative, and I don't have much that I can pay him back with. That's what matters to me. Maybe I just have a conscience, and appreciates great help when I sense it.

Thanks Scorp.


[Modified by lampedusa, 8:32 PM 10/3/2002]

 

You're right...Scorp helps others out unselfishly...I feel like such a schmuck for scoffing him... :sad:

...But I was hoping he'd have something to say about the 100 long pushrods 'cause I've never heard of them...

(edited due to etc.)


[Modified by Rich B., 9:19 PM 10/3/2002]

 

:yesnod: I used the same length pushrod as I measured. I have not heard of the "100 over" thing either. :cheers:

 

And exactly how old do you think the wise old sage Scorp is?

We had to sneak him into bars when we met him.:D

 

Lamped,

Sorry I missed this thread so many times, not sure how I managed that one. I've been outside since 6pm trying to fix why my car isn't charging correctly. Will find out if I got it right in the morning.

As for Rich B... he and I we are always ragging on each other all in fun, no worries. :) He's just mad that he got a new male nurse at the old age home and the female one got assigned to his neighbor. :D

The pushrods I honestly couldn't tell you what length mine are. I bought my pushrods, springs, retainers, shims, lifters all from Lingenfelter back when I did my top end. I told them what cam and roller rockers I was going to be using and they put it together for me. The part # from LPE was LN0280H
for $34.95. They are 5/16" heat treated with welded in tips. Not sure on the legnth.

And yeah.... I'm 22 now, the NE crew would get me in places when i was still 20. :D

 

The .100 longer pushrods is used mainly when going to a camshaft with a smaller base circle. Most cam companies larger lift camshafts that are "on the shelf(not custom ground or specific grind cams) have a .100" smaller base circle thans standard small block cams, therefore the need for .100 longer pushrods to make up the height difference. I have never ran into a situation of just changing rockers, going to 1.6 or roller or whatever, that has required the need for longer pushrods. If you were to check the contact area of the rocker arm where it rides on the valve stem face, if your pushrods were the wrong length, the contact area would not be centered on the stem face. When you turn the engine over slowly you will notice that the contact surface, when the lifter is all the way down, is off from center(actually closer to the rocker stud side of the face"inside") and as the lifter comes up opening the valve the contact surface will move "out" towards the center going past and then coming back "in" until it is the same distance from center at full lift that it is when it is fully closed. This would be the "correct" pushrod length. It is very hard to get it exact, just be sure that the rocker contact surface does not come to far to the inside, it could actually fall off the stem and bind up causing a catastrophy! :eek: One of the most important things to look for when going up to 1.6 rockers is the pushrod slot or hole that is in the cylinder head that the pushrods goes through. All of the aftermarket heads usually have a longer slot or big hole around the pushrods, but stock gm heads are sometimes to small. This will allow for the pushrod to actually rub against the cylinder head and cause more problems. This is from the "cup" in the rocker arm, that the pushrod sits in, is closer to the center pivot of the rocker arm therefore moving the pushrod "out" closer to the end/edge of the hole in the cylinder head. If all you are changing is the rocker arms, just check the pushrod clearance in the cylinder head, and you should be fine. As for the 7/16 diameter, you do mean rocker arm studs right? A 7/16 dia. pushrod is way overkill! The length of the pushrod has nothing to do with the "full stroke of the rocker arm". The amount that the rocker arm strokes is only affected by the amount of lash, and the actual lobe lift on the camshaft. I guess if you have a hydraulic lifter that is weak and not fully "pumped up" this would also make that particular rocker arm stroke change due to the fact that it will "compress" more as it tries to open the valve. I hope that I didn't confuse you, it would be easier to show you! Good luck. :cheers:


[Modified by sinistervette, 3:18 AM 10/4/2002]

 

That makes sense. You can only get so much lift without the lobe hitting the bearing on installation (lobe would be higher than bearing journal), so they grind more off the "back" of the cam lobe to get increased lift.

That would explain the longer pushrods.

I've always used OEM GM cams (1963 FI cam; 1964 FI cam; Z28 cam; etc), which all conform to std GM patterns; never had to worry about longer pushrods...

Good to know... :D