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I have a set of Scorpion 1.6:1 roller rockers. The heads have been machined for larger studs; but I don't know how to determine if the studs I have are the correct ones because they are 2.497" in length and I have been told they are way too long (as far as diameter, they screw in fine [both into the head (the coarse side) and into the poly locks] but I don't know how to verify the size i.e. are they 3/8, 5/16 or 7/16?).
These are the studs that I received in the debacle with BW@WPE, which does not surprise me. Several items have been wrong to this point.
Can someone point me in the right direction for getting the right rocker studs please?
Measure the shank diameter and it will tell you the size, 5/16 - 7/16. You can use a caliper, an open end wrench slipped over it, or a known sized nut to screw on it.
Measure the shank diameter and it will tell you the size, 5/16 - 7/16. You can use a caliper, an open end wrench slipped over it, or a known sized nut to screw on it.
Oldcutlass,
The head side (coarse thread) is 7/16 and the rocker side (fine thread) is 3/8. The thread count for the 7/16 is 14 and the thread count for the 3/8 is 20.
I have no idea where to find these in the 1.9 inch range if that is the right size to use with guide plates.
What is NF? Also, according to my tap and die thread measuring kit 20 fit and 24 didn't...
Bryon
Octania,
I am very sorry for my hasty reply. Frustration is setting in...I remeasured the threads and they are 14 on the 7/16 side and 24 on the 3/8 side. My apologies, friend.
What is NF? Also, according to my tap and die thread measuring kit 20 fit and 24 didn't...
Bryon
Sorry, NF is standard shorthand for National Fine threads. There are MANY types of threads, but for fractional inch components, 99% of what 99% of us work with in this country are either
1) NC ["coarse"] or
2) NF ["fine"] threads.
Unless you get into specialized industries or particular fairly obscure applications.
Here is more than most Engineers need to know about thread form details thru 1".
Note that OF COURSE of the two obvious ways to specify thread spacing or pitch, the fractional system uses "threads per unit length" such as the 3/6-24 which is 24 threads per inch, whereas the metric format is "unit of length per thread" so for example a metric with a pitch of __-1 is 1.0 mm per thread. Inverse ways of describing the same thing. God forbid we pick one and stick to it. Mostly because of the Curse of Fractions. I do not understand why the world still uses fractions. At least they kept it to powers of 2, like 1/2, 1/4, 1/64, etc. Haven't gotten into stuff like 7/13 or 111/251 of an inch.... yet. But, I digress.
There is also an oldschool paper book [remember those?] called "machinery's handbook" which details pretty much every facet of anything mechanical- keyways, shafts, tolerances, interference fits, running fits, etc. The basic info that has allowed us to make and use machines for 100's of years. There is SO much info in there, though, that finding what you need can be challenging. Like, how deep should you run the cutter when making a keyway for a woodruff [half moon] key? It's in there.
Lately I have been working on big-*** metal stamping presses, and they use some big-*** threads. Like 1-1/2 or 2" threaded holes for handling the pieces during service, assembly, etc. This week I was tasked with "reverse engineering" or making a drawing from an actual part, already assembled, with a round nut having threads I had to guess at, since it was assembled. Bossman reckons it is 1&3/4-8 or something like that.
I used the studs from the comp roller tip rocker arms with my Scorpion SBF 1.72 roller rocker arms. As long as the studs don't hit the valve covers or the poly locks don't bottom out before properly tightening, you will be fine.
I'm not sure where you come up with 7/16 bottom and 3/8 top. It looks to me like the stud is 7/16 x 7/16.
I would have talk to Brad as to what is going on.
I'm not sure where you come up with 7/16 bottom and 3/8 top. It looks to me like the stud is 7/16 x 7/16.
I would have talk to Brad as to what is going on.
Gene
Gene,
I get it based upon oldcutlasses suggestion to measure the stud on both sides. The block side is 7/16 and the rocker side is 3/8 - that's how they measured out. It's only 1/16 difference, maybe the picture just doesn't show it.
I need to revisit this question because I still don't have a clear understanding of what is needed. Here is some basic information about my situaion:
I have a 350 with #5 heads that have been machined for 7/16 (threads: 14) screw in studs and the Scorpion roller rockers I have are 3/8 (threads: 24). I am looking for information on the following:
1. What maximum overall length stud will work with stock valve covers? The rocker studs I currently have are 2.497" and I have been told they are too long (and with guide plates they would sit even higher). I saw that someone mentioned that if the poly locks don't bottom out and the studs don't hit the valve covers they should be okay, but I'm more concerned about geometry, making sure that it will work in the sense of finding the right pushrod length and such...
2. Does anyone here have this same stud configuration (threads, not length)?
3. Are guide plates necessary? I have a mild street roller lunati and erson roller lifters.
4. If guide plates are necessary, which ones will work? I bought a set of comp cams guide plates (COMP Cams Pushrod Guideplates 4810-1) that were supposed to work but they were about 1/4 too narrow (not allowing for the stud hole and the pushrod slot to line up properly).
If there is more information needed I'd be glad to provide it.
I am just trying to figure out what is needed so I understand how to proceed. I fear I am wearing out my welcome with a good man, so I want to see if I can figure this out elsewhere. I am nearing the end of the build but I'm kinda stuck in neutral on this one...so close I can taste it after such a long, looonnnng time. I am looking forward to this getting finished up so I can drive it after it sitting for over two years for no good reason.
Typically when guide plates are installed; the rocker pedestals are machines down to compensate for the added height of the guide plate, if this has not been done then you are going to have problems with the rockers binding. If the pedastals have been machined then you just need to worry about if it will fit under your valve covers and if there is enough adjustment. Unfortunately some of this stuff is mocking it up and trial and error.
Typically when guide plates are installed; the rocker pedestals are machines down to compensate for the added height of the guide plate, if this has not been done then you are going to have problems with the rockers binding. If the pedastals have been machined then you just need to worry about if it will fit under your valve covers and if there is enough adjustment. Unfortunately some of this stuff is mocking it up and trial and error.
Thanks Gary. I don't know if the rocker pedestals have been machined. I am trying to find a picture of a stock #5 head to I can compare to see the difference. The heads have been ported, bigger valves, drilled for 7/16 screw in studs and milled to about 60cc chambers. That's about all I know. I can post a picture to see if anyone here would know it. My concern is that I hear about bent pushrod all the time. I understand that even if the guide holes in the head are large enough for the pushrods (with room to spare) the pushrods need more than being centered in the lifter and in the rocker arm cup for security.
Anyway, do you think posting a picture would help?
Sorry for the late reply. Just did some measurements. My guide plates are comp. cams and they are .070 thick. The pedastals have been machined down until they are even with the valve cover gasket surface. I couldn't take any pics because I was having problems measuring and taking pics at the same time. Hope this helps.
Sorry for the late reply. Just did some measurements. My guide plates are comp. cams and they are .070 thick. The pedastals have been machined down until they are even with the valve cover gasket surface. I couldn't take any pics because I was having problems measuring and taking pics at the same time. Hope this helps.
Thanks Gary! No lateness, I just appreciate the reply! Mine must have been machined down then because the entire flat surface of the heads are even (the valve cover plane and the point at which the guide plates are placed). It seems that our heads were done the same. Do your rocker arm studs have a 7/16 base thread also?
April 29th, 2016, 12:18 PM
