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-   -   Scorpion Roller rocker problem SBC (http://www.hotrodders.com/forum/scorpion-roller-rocker-problem-sbc-161169.html)

maliboo 07-05-2009 10:41 AM

Scorpion Roller rocker problem SBC
 
I bought a set of scorpion roller rockers for my sbc street engine. When i was installing them i ran into something that i didnt expect, and had to screw the stock rockers back in.. The problem is that the bottom of the roller rocker body will collide with my heads, just where the stud is pressed in. Do i need different length pushrods or something? Or just grind some material off from head/rocker?


Cheers,

Maliboo

F-BIRD'88 07-05-2009 11:39 AM

Something is very strange about that. May have non chev rockers in a box with a SBC part number. How close to the rocker stud boss is the bottom of the stock rocker arm when adjusted?

JeffB 07-05-2009 11:42 AM

Rockers
 
If you haven't upgraded to screw-in studs,why are you putting on roller rockers in the first place? :confused:

maliboo 07-05-2009 12:21 PM

Quote:

Originally Posted by JeffB
If you haven't upgraded to screw-in studs,why are you putting on roller rockers in the first place? :confused:

I have my reasons, and i dont see how screw-in studs would solve this problem? Mild cam and mild springs, pressed studs will hold. It is not that i would need rollers, i just want them :P


I've read about similiar problems from this forum earlier, and on at least one thread this was solved by grinding material off from the rocker body to prevent the collision. Not much material would be removed, only like .050" - .100" and from a small area only. But would longer pushrods help me on this? or will it just crap my valvetrain geometry?

maliboo 07-05-2009 12:24 PM

Quote:

Originally Posted by F-BIRD'88
Something is very strange about that. May have non chev rockers in a box with a SBC part number. How close to the rocker stud boss is the bottom of the stock rocker arm when adjusted?

This is just it. I cannot adjust them fully, because the rocker body will hit the stud boss just where i would need to add preload. So i'd need something like .050" - .100" material removed from stud boss or from rocker arm.

JeffB 07-05-2009 12:38 PM

Get it straight thru the source:www.scorpionperformanceblog.com/ Who would know better?

F-BIRD'88 07-05-2009 12:51 PM

Quote:

Originally Posted by maliboo
This is just it. I cannot adjust them fully, because the rocker body will hit the stud boss just where i would need to add preload. So i'd need something like .050" - .100" material removed from stud boss or from rocker arm.

Are you saying you cannot install and adjust the OEM stock rockers on your heads?

If so the scorpions have no chance.
List all details. What is stock what is modified, what machine work?

maliboo 07-05-2009 12:55 PM

Quote:

Originally Posted by F-BIRD'88
Are you saying you cannot install and adjust the OEM stock rockers on your heads?

If so the scorpions have no chance.



AAAAAAaa, yes the stock ones will clear. with them i have about .200" - .250" space when adjusted. The scorpions start to hit the stud boss just before i'm about to turn the last 1/2 turn for preload.

F-BIRD'88 07-05-2009 01:09 PM

what cylinder head casting? Are you sure you are not going way beyond the 0 lash point when "adding preload" (compressing the lifter internal plundger)

maliboo 07-05-2009 01:54 PM

Quote:

Originally Posted by F-BIRD'88
what cylinder head casting? Are you sure you are not going way beyond the 0 lash point when "adding preload" (compressing the lifter internal plundger)


casting # 14014416. Yes, i know how to adjust valves :P with scorpions i can get them to the point where oily pushrod no longer rotates easily by fingers, but thats it, if i tighten more it will just clamp my rocker to stud boss and -> rocker will not "rock".

I cannot check for geometry errors because i cannot adjust valves properly. Would not want to buy longer pushrods just for the fun of it, so would it be ok just to make room by removing material from somewhere? that way i could at least get to rotate the engine with adjusted valvetrain and check if roller tip aligns properly to valve tip or not.

eloc431962 07-05-2009 01:58 PM

Why dont you take the heads and have them machined down and add screw in studs with guide plates, should solve your problems. What part number are the rocker arms you trying to install? JMO . Cole

cobalt327 07-05-2009 02:10 PM

To start with, measure the p-rods that are in it now to be sure they're not shorter than stock.

You say you know how to adjust valves. This may be true but bear w/me for a moment.

When you are twisting the p-rod to determine that the lash has been removed, and can begin to turn down the adjusting nut to get the proper preload, the "oily pushrod no longer rotates easily by fingers" part is what I'm questioning.

There should be no point when "zero" lash has been met that the p-rod should no longer rotate easily- it sounds like you're too far and have bottomed out the plunger in the lifter body and are now against the valve spring pressure.

When at "Zero" lash, the p-rod will still rotate very easily, there's only a very slight amount of drag that is created when the p-rod and lifter plunger/seat have met.

Bottom line- adjust the valves correctly and there will be no bottoming out of the rocker on the stud boss. Just be glad that you didn't bend any valves or p-rods by trying to run the engine like this.

You may need a slightly different length of p-rod to adjust the geometry to perfection, but stock length will work to get the valves adjusted to check it if you don't have a tool to check p-rod legnth.

maliboo 07-05-2009 02:16 PM

Quote:

Originally Posted by eloc431962
Why dont you take the heads and have them machined down and add screw in studs with guide plates, should solve your problems. What part number are the rocker arms you trying to install? JMO . Cole


Rocker part no #SCP1002.

Just had the heads off for port and valve job couple of months ago. Didn't have the $$ to buy rollers then, and wasn't going to for some time anyway, so didn't see the need to upgrade for screw-in studs with stock rockers..
I then got some cash and bought these scorpions from local speed shop. He sold me the right product, of that im sure, i even talked to the guy about this and he told me to check pushrod length. well, shorter pushrods will not help me so i think maybe .100" - .150" longer pushrods would give me enough room..

maliboo 07-05-2009 02:24 PM

Quote:

Originally Posted by cobalt327
To start with, measure the p-rods that are in it now to be sure they're not shorter than stock.

You say you know how to adjust valves. This may be true but bear w/me for a moment.

When you are twisting the p-rod to determine that the lash has been removed, and can begin to turn down the adjusting nut to get the proper preload, the "oily pushrod no longer rotates easily by fingers" part is what I'm questioning.

There should be no point when "zero" lash has been met that the p-rod should no longer rotate easily- it sounds like you're too far and have bottomed out the plunger in the lifter body and are now against the valve spring pressure.

When at "Zero" lash, the p-rod will still rotate very easily, there's only a very slight amount of drag that is created when the p-rod and lifter plunger/seat have met.

Bottom line- adjust the valves correctly and there will be no bottoming out of the rocker on the stud boss. Just be glad that you didn't bend any valves or p-rods by trying to run the engine like this.

You may need a slightly different length of p-rod to adjust the geometry to perfection, but stock length will work to get the valves adjusted to check it if you don't have a tool to check p-rod legnth.

Im not pushing lifters too far, I only meant that i tighten as long as i feel a lash when i rotate the pushrod. when i feel the lash disappears, i add the preload. this is how i do it with the stock rockers and the preload is correct, or if not spot on, it will be on the loose side rather than too tight.

I'll dig the pushrods out and measure them next.

One thing popped in my mind - are comp cams lifters shorter than stock? that could very well cause this.. it has comp 268xe cam and comp lifters.

techinspector1 07-05-2009 02:29 PM

Quote:

Originally Posted by maliboo
casting # 14014416. Yes, i know how to adjust valves :P with scorpions i can get them to the point where oily pushrod no longer rotates easily by fingers

Using the twist method, I'd say that you definitely do not know how to adjust valves.

While holding the rocker tip down against the valve stem tip, jiggle the pushrod up and down and tighten the adjusting nut until all play is removed. Tighten the adjusting nut another 1/2 to 3/4 of a turn to set pre-load. Done.


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