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  #16 (permalink)  
Old 07-05-2009, 04:14 PM
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There is about a 90% chance that 1.6 ratio rockers will cause the pushrod slot to interfere with the pushrod at the stud end of the pushrod slot. To make a 1.6 rocker, they just move the pushrod cup towards the stud on the rocker body.

You can't just slap a 1.6 rocker on and go.

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Old 07-05-2009, 04:33 PM
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Trust me on this one, my valve adjustment is correct, this has been verified by a person who knows for sure how to do it, im just having a hard time explaining how i adjust them, this is not my native language you know

Rockers are chevy rockers, lifters are stock height, i measured my pushrods, they are stock (compared to another stock sbc pushrod). Cam could be smaller base circle.. thats the only place that could be "shorter" than stock.

I cant locate the thread now but i read about this same problem here couple of days ago, cant remember what was the reason why it happened on that case..
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  #18 (permalink)  
Old 07-05-2009, 04:52 PM
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Quote:
Originally Posted by maliboo
Cam could be smaller base circle.. thats the only place that could be "shorter" than stock.
I don't recall the other thread just now.

There are different length valves, if they were changed during the head work that was done, they might account for it.

It's just that thousands of those rockers have been installed on heads like yours- w/o drama. So if there's nothing wrong w/how they're adjusted, it's something in the parts themselves.

I would start measuring things, as compared to known "correct" or OEM parts. Something is short, and not just a little bit, to cause this to happen, IMO.

How much thread is showing above the adjuster nut? Or are you using P-locks? If poly locks, is there plenty of engagement for the locking allen head?

Is the same thing happening on both the intake and exhaust valves? ALL the valves, or just some of them?

EDIT- If you think it'll help, I can walk out to the shop and measure the amount of valve stem that extends up past the valve guide boss on the valve cover side of the head (stock head and valves)- for a comparison to what yours measures.
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Old 07-05-2009, 05:52 PM
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Quote:
Originally Posted by techinspector1
Using the twist method, I'd say that you definitely do not know how to adjust valves
Comments like this make me laugh. I use this method all the time and I definitely know how to adjust valves.
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  #20 (permalink)  
Old 07-05-2009, 08:04 PM
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Quote:
Originally Posted by engineczar
Comments like this make me laugh. I use this method all the time and I definitely know how to adjust valves.
Yeah, well maybe that was too sweeping as a general statement, but you've probably done this thousands of times and have a feel for it, whereas the OP hasn't your experience.
Cut this old man some slack, dude.
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Old 07-05-2009, 08:10 PM
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Quote:
Originally Posted by engineczar
Comments like this make me laugh. I use this method all the time and I definitely know how to adjust valves.
I was going to say what the Inspector did too. The "spin" method gets more amateur's in trouble and I don't like it either, especially with hydro lifters. I know how to use this method too, but it shouldn't be a recommended method.
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Old 07-05-2009, 09:35 PM
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I really don't want to turn this into a thread about how to adjust valves. The process of setting the valves is inherently a precise procedure no matter how you do it and does require a pretty good sense of feel to get it right no matter which procedure one chooses to use. However just because someone poses a question doesn't automatically make a person an amateur and I think it does a tremendous disservice to the original poster to imply that he doesn't have the skill to adjust the valves a certain way. I don't think the problem he's having is related to how he's adjusting his valves but has more to do with the combination of parts he's working with.

Like what has already been posted I would check the clearance of the pushrod slot due to his using 1.6 rockers. I would also check with the machinist as to whether or not the valves are stock length or +.100, other things to consider are the combination of deck height/head gasket thickness/head deck thickness combining to necessitate a longer pushrod or just a plain old out of whack head casting that has left the rocker stud bosses too high. While nice pieces the Scorpion rocker arms do tend to be a pretty bulky design.
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Old 07-05-2009, 10:16 PM
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Quote:
Originally Posted by engineczar
However just because someone poses a question doesn't automatically make a person an amateur and I think it does a tremendous disservice to the original poster to imply that he doesn't have the skill to adjust the valves a certain way.
But assuming an OP (not this thread's OP) has mad skilz is the one thing that most often gets me burned when giving advice! lol

It seems if I give credit for knowing the basics, sure as heck, the next post will be that all the "carb problems" were really a burned plug wire that the lawn service guy found while he was there cutting the grass! And then if I were to go into some long, drawn out description of how to tune the idle circuit of his carb, he'll come back and say, "Oh, BTW, I'm the head technician at XYZ Carb Co.".

Quote:
I don't think the problem he's having is related to how he's adjusting his valves but has more to do with the combination of parts he's working with.
That's what it's sounding like, as long as the OP has a grip on the valve adjustment thing. Which brings us back full circle!
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Old 07-05-2009, 11:04 PM
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I cannot see how valve adjustment could even solve this. If i cannot even apply preload, on some valves i cant even get all the lash away before rocker gets jammed, it cannot be the reason why it does this. Good to check of course, but in this case it isnt the case. As for if i know how to do it or not, why does my engine work with stock rockers perfectly, and has done so after many times ive been adjusting them....?

Nuts are polylocks, and the allen nut is about at the same height than the hex nut, so it really does not come out too much.

I have to speak with the machinist who did my valve job. Maybe he used long-tip valves. The locking groove, however, is at correct height, i know this because i measured valve spring heights and they were same as stock..
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Old 07-08-2009, 03:44 PM
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Quote:
Originally Posted by F-BIRD'88
When the valve lifter is all the way down in the lifter bore and on the cam base circle, does it sit below the edge of the lifter bore? (Lower than with a stock GM cam) What cam is in the motor?

Lifter sits right at the edge of its bore when its on the base circle. Camshaft is Comp Cams xtreme energy with 268 / 280 adv. duration.

I talked with the machine shop dude. Valves are stock length.

Maybe my heads just are more bulky than normally, for some odd reason? Anyway, in this case these rockers wont fit without removing heads, so I'll just have them converted to threaded studs and machine stud bosses down. Then check for pushrod length and buy new pushrods if necessary.
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Old 07-08-2009, 05:40 PM
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Quote:
Originally Posted by techinspector1
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.

Not to step on toes, but sometimes only 1/4 turn is needed, I usually only go 1/4 as I have seen 1/2 turn actually cause a valve to hang slightly open with a stock cam. But yea, use the "jiggle" method, not the "twist" method... Now that sounds scientific.
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Old 07-08-2009, 06:21 PM
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Quote:
Originally Posted by maliboo
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
This is not an uncommon problem, especially when not replacing the press in studs as this leaves the rather high stock boss that is just enough to clear stock coined rockers. Also, the change to 1.6 typically requires that you correct the push rod length, which will fix the standing height of the rocker.

Bogie
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  #28 (permalink)  
Old 07-08-2009, 10:41 PM
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Your valvetrain geometry is what dictates push rod length. You need to get a solid lifter and an adjustable push rod. Check to see what length pushrod this combination is calling for. There are too many variables to just assume anything.

As mentioned you also need to check push rod slot clearance and if they need to be opned up, the heads are going to have to come off anyway. Save up a little coin to get screw in studs and be done with it. Down the line you will want more power and a bigger cam, that's just the way it works.

The problem could very well be that the rockers are just too thick for the room you have.
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