Thought that was a picture of my 690s. LOL!Had plenty or room on mine with big trunnions. View attachment 93711
I'm sorry, the studs not the arms. Just realized my mistake.S2001np I believe
I am not sure as the heads were machined for screw in studs over 20 years ago when the car was built.I know this because I just dealt with this issue myself awhile back but I knew my issue was not my rocker arms but the studs I had weren't the studs I needed based on measurements taken. What changes if any have you made to your rocker arm STUDS length and would that make any difference in your case is my question. Every machine shop taps rocker arm studs differently. Did they go to low in your case? I'm pulling apart a set of 690's for a buddy of mine and his aren't done the same as mine were. His seem to work fine it seems but all things to consider where the rocker arm may not be the actual problem. I don't care if you need a 2" valve cover spacer to make taller rocker arm/studs fit, there really is no one size fits all with these girls.
Try to figure out which studs you have and find ones that are longer and test fit one. A few of my friends let me barrow some singles until we found the right length. I had a set of screw in studs I thought I was going to use but found they were 1/4 to short. Ordered the taller rocker stud and problem fixed.I am not sure as the heads were machined for screw in studs over 20 years ago when the car was built.
With the adjustable pushrod, I'm using lightweight checker springs. Pushrod wise I'll probably eng up using trend or Manton .130 wall thicknessCouple of things I've found out through the years:
-Don't get all hung up on having the rocker arm exactly in center of the valve stem. While this seems like the perfect plan, the reality is that as you shorten the push rod to do this, you lose lift at the valve. As long as the contact is from the center to the outer 3rd (w/o running off the valve tip, obviously), you'll be fine.
-Pushrod length, in and of itself, is immaterial as long as the lift at the valve is close to what it should be and the pattern on the valve tip is within reason (see above).
-Bigger/stronger pushrods cure a lot of valve train ills. I won't bore you with the math, but as an example...a 3/8" .080 wall pushrod is nearly 50% stronger ('stronger' as resistance to deflection) than a 5/16" .105 wall pushrod of the same material.
Based on your excellent pics, you have quite a few mock ups that I'd run with no second thoughts....provided the pushrods were stout. Remember that if you're using an adjustable pushrod for checking lengths, these things are about as rigid as wet noodle when it comes to deflection unless you use a light checking spring.
Hope this helps.
I plan on trying a couple different rockers including a .050 backseat crower rocker before I make a final decision. Like I said, car is mostly a cruiser but if I decide to play a little I want to be ok.Couple of things I've found out through the years:
-Don't get all hung up on having the rocker arm exactly in center of the valve stem. While this seems like the perfect plan, the reality is that as you shorten the push rod to do this, you lose lift at the valve. As long as the contact is from the center to the outer 3rd (w/o running off the valve tip, obviously), you'll be fine.
-Pushrod length, in and of itself, is immaterial as long as the lift at the valve is close to what it should be and the pattern on the valve tip is within reason (see above).
-Bigger/stronger pushrods cure a lot of valve train ills. I won't bore you with the math, but as an example...a 3/8" .080 wall pushrod is nearly 50% stronger ('stronger' as resistance to deflection) than a 5/16" .105 wall pushrod of the same material.
Based on your excellent pics, you have quite a few mock ups that I'd run with no second thoughts....provided the pushrods were stout. Remember that if you're using an adjustable pushrod for checking lengths, these things are about as rigid as wet noodle when it comes to deflection unless you use a light checking spring.
Hope this helps.
I need to replace all studs I believe as there is evidence of the old rockers hitting the studs due to too short of a pushrod. Nothing appears to be bent or broken, and compression check as well as leak down was beautiful.Try to figure out which studs you have and find ones that are longer and test fit one. A few of my friends let me barrow some singles until we found the right length. I had a set of screw in studs I thought I was going to use but found they were 1/4 to short. Ordered the taller rocker stud and problem fixed.