rockers sitting crooked,dont no y
02-24-2011, 08:02 PM
#1
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rockers sitting crooked,dont no y i am in the process of measuring for pushrod length when i found that my rockers are sitting crooked.i have scorpion nsa 1.6 rr and comp 4808 guide plates.any ideas is this common?
02-24-2011, 09:41 PM
#2
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More than likely those guideplates (you might find that some cylinders are more lined up than others). LT1s are slightly different to the SBC in that area.
Some options with better fit:
GM p/n 14011051 (8 needed) (good idea to double-check them with a file for hardness)
Trickflow Part # 30400623-8
or adjustable guideplates
Some options with better fit:
GM p/n 14011051 (8 needed) (good idea to double-check them with a file for hardness)
Trickflow Part # 30400623-8
or adjustable guideplates
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02-25-2011, 10:27 AM
#9
In the past I have run GMPP guide plates and noticed that at least one rocker per cylinder did not sit in the ideal position. The ones that were off always had a wear mark on the outer edges of the slots on the guide plates while the inner edges of the slots were never touched by the push rods. It was also very obvious that some valve tips were not totally covered by the rocker rollers which obviously is not desirable. I actually had one were 1/5 of the valve tip was not contacted by the roller.
I once bought some Trick flow guide plates and compared them to the GMPP and found the slot dimensions to be 100% identical and neither had any significant room to allow adjustment by loosening the studs. I think in short and mainly due to manufacturing tolerances of the heads, there is not a "bolt up and run" guide plate that does an ideal job locating the rockers perfectly on the valves. IMO, it appears that the slots on these guide plates are a tad too close together for ideal alignment, but there is a solution to the problem.
The Isky adjustable guide plates allow you to tailor the guide plates to better position the rockers in their proper positions per cylinder. The only catch is it is a painfully long process to do dial them in and it involves lots of trial and error and readjustments. Once they are dialed in, it is best to tack weld the plates to ensure they dont lose their setting especially if the need arises to loosen or remove the studs.
It took me nearly 8 hours to completely dial in my Iskys just about a month ago and the final results were very much worth the effort. The funny thing is not all of the finished guide plates slot dimensions are the same. Some guide plates have the slots further apart for one cylinder versus another so this confirms the issue with the heads manufacturing tolerances IMO. The one thing to remember is you must run the motor when testing the guide plates for proper adjustment. Simply eyeballing it or slow cranking the motor will not provide good results.
The rockers are now much better aligned and at a glance will look perfect to the eye compared to before plus all the valve tips are now completely covered by the rocker roller. There are still some tolerances that will prohibit 100% perfect alignment all the time like the roller on the rocker shifting within the rocker body and the clearance of the push rod within the guide plate slot but the Iskys go a long way to getting the rockers aligned the way they should ideally be.
I once bought some Trick flow guide plates and compared them to the GMPP and found the slot dimensions to be 100% identical and neither had any significant room to allow adjustment by loosening the studs. I think in short and mainly due to manufacturing tolerances of the heads, there is not a "bolt up and run" guide plate that does an ideal job locating the rockers perfectly on the valves. IMO, it appears that the slots on these guide plates are a tad too close together for ideal alignment, but there is a solution to the problem.
The Isky adjustable guide plates allow you to tailor the guide plates to better position the rockers in their proper positions per cylinder. The only catch is it is a painfully long process to do dial them in and it involves lots of trial and error and readjustments. Once they are dialed in, it is best to tack weld the plates to ensure they dont lose their setting especially if the need arises to loosen or remove the studs.
It took me nearly 8 hours to completely dial in my Iskys just about a month ago and the final results were very much worth the effort. The funny thing is not all of the finished guide plates slot dimensions are the same. Some guide plates have the slots further apart for one cylinder versus another so this confirms the issue with the heads manufacturing tolerances IMO. The one thing to remember is you must run the motor when testing the guide plates for proper adjustment. Simply eyeballing it or slow cranking the motor will not provide good results.
The rockers are now much better aligned and at a glance will look perfect to the eye compared to before plus all the valve tips are now completely covered by the rocker roller. There are still some tolerances that will prohibit 100% perfect alignment all the time like the roller on the rocker shifting within the rocker body and the clearance of the push rod within the guide plate slot but the Iskys go a long way to getting the rockers aligned the way they should ideally be.
Last edited by wrd1972; 02-26-2011 at 07:33 AM.
02-25-2011, 08:07 PM
#11
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thanks,im undecided if i want to send the nsa rockers back for sa and make it easy or if i want to go through the hassle of getting adjustable guide plates and trying to adjust them myself since im un experienced and if i do something wrong it could cost me alot of $.
02-25-2011, 08:12 PM
#12
Even though the GMPP or Trickflow guide plates dont perfectly align the rockers, most people agree they will get the job done. I never really had an issue with mine except for the crooked appearance they gave off. Obviously the SA rockers are the easiest way out but many believe they are not as stable at very high RPM's.
02-25-2011, 09:55 PM
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i was told that the heads should be machined where the studs screw in the same thickness as the guide plate since the heads werent originally eqipped with guideplates.
02-26-2011, 09:17 AM
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I don't mean to hijack but I've been trying to decide between self aligning and guideplates. What's the downside to self aligning rockers? Most people I see are running guideplates.
02-26-2011, 02:03 PM
#19
Regarding guide plates for LT1 heads, IMHO, the ISKY allow specific alignment and for me provided better RR to valve stem alignment.
and i only rev mine to 6500 