Scorpion Rocket PSA

Ishiftem

Well Known Member
Supporting Member 2
#1
After having some run time on my scorpion roller rockers, I have noticed three are not square to the rocker stud and valve tip. It is definitely in the rocker and can be seen in the wear pattern on the valve tip. No damage but something to look for if you have or are buying a set.
 

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63 dream'n

Well Known Member
Supporting Member 3
#2
Hey Dan..... just thinking out loud here ...question, if you had deflection in the rocker stud, the deflection would wanna go straight back and straight towards the valve .....correct .....??? so even if you had a stud girdle .... The stud girdle would prevent movement the opposite way correct ....???? you shouldn’t have any side to side movement..... so does that mean it would be in the machining of the trunnion ......??? Thanks in advance
 

Ishiftem

Well Known Member
Supporting Member 2
#3
Stud girdle helps stabilize the stud like you said. I can put one of the bad rockers on any stud and pull it up against any of the nuts and it doesn’t change. It crooked. As best as I can measure from the bottom of the trunnion bore to the bottom of the rocker body, there is about a .010 difference. And it’s off in a way that would cause the rubbing where it is.
 

63 dream'n

Well Known Member
Supporting Member 3
#6
Stud girdle helps stabilize the stud like you said. I can put one of the bad rockers on any stud and pull it up against any of the nuts and it doesn’t change. It crooked. As best as I can measure from the bottom of the trunnion bore to the bottom of the rocker body, there is about a .010 difference. And it’s off in a way that would cause the rubbing where it is.
I would think even used, you would be able to “prove” that to the engineers and get those replaced .........?????......!!!!!
 

63 dream'n

Well Known Member
Supporting Member 3
#8
After having some run time on my scorpion roller rockers, I have noticed three are not square to the rocker stud and valve tip. It is definitely in the rocker and can be seen in the wear pattern on the valve tip. No damage but something to look for if you have or are buying a set.
So when we’re taking care of the ones that we love ......what kind of new jewelry does she get........ does she get new valve springs, keepers...??? do you rebuild anything with the trunnion......???
 

Ishiftem

Well Known Member
Supporting Member 2
#10
I’m going to try Petey, but I’m expecting “we have never had that problem before”. Jewelry? This is the definition of mission creep. Started by removing the intake to get the head runner angle for modifying an 881 into a single plane intake. Engine builder “ Take a head off and use my flow bench to test different runners”. So off came a head. Then I confirmed I’m getting some oil in the chamber. Not good at this compression. So out with the whole works. Hone and a little different ring package. Pistons are getting line2line apc coating. New bearings. Touch up the valve job. Intake seat is a little sunk next to the exhaust seat. New springs, retainers, and locks. From titanium to tool steal retainers. I hate seeing glitter in my oil from the titanium wearing. Maybe a little more work to the intake ports. Had a corrosion issue with Manley severe duty exhaust valves so switching to Ferrea. I want this bitch in the 9s!
 

63 dream'n

Well Known Member
Supporting Member 3
#16
When Nick (Bossman) Was porting my heads, he got in contact with JoMar and had them make up the 409 stud girdle ...... it took forever ...... but obviously I was not in a hurry because my heads are still in the closet .....and I asked Nick If my motor would actually benefit from the stud girdle...... and he said he saw deflection fairly low in the RPM range .......power gains were made by 6000 RPM ......which I’m sure you’re achieving.......Just food for thought .....I know that you guys are a lot smarter than I am......
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Ishiftem

Well Known Member
Supporting Member 2
#18
The higher the rpm and spring pressure the more gain you will see. Usually a 5-10 hp gain. You do need to fit them. When tightened down, they should put no pressure on any of the studs. So if you have a stud that is a little out of line with the others and you don’t correct for that, it can break the stud. Not common but does happen. They just seem like a pain to me. I think I’ll just wait and jump right to shaft rockers some day.
 
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