rapom65
Well-Known Member
I purchased a pushrod length checker due to recent head & rocker changes. Done a bunch of reading through old threads but I'm not finding consensus answers to my questions. Engine: 360, Eddie RPM package (heads/manifold/hyd cam) and Crane Gold adjustable rockers.
So, riddle me this Batman (you know your old if you understood that!!):
1. Adjuster threads. Recommendations ranged anywhere from 1 to 4 threads showing after preload is set. I have not been able to find on-line what Crane actually specifies, if they do. I stared at my valve train for quite a while yesterday trying to figure out what difference it makes. Why does there need to be any threads showing? My guess is geometry but I thought up many reasons; optimized oiling of the ball & cup, adjuster strength, pushrod cup to rocker/spring retainer to rocker interference, manufacturer's design spec, ect..... My old pushrods, from my iron heads. result in the threads just begining to emerge, or 0 to maybe 1/2 thread showing on all rockers. I could find no binding issues anywhere and plenty of clearance everywhere. Can some of you more knowledgeable gents enlighten me on what the significance of # of threads showing results in, and why, so I can justify to myself the expense of new pushrods?
2. Preload. My old pushrods, with 0-1/2 thread showing, is with 1/2 turn on the adjuster which supposedly = .030 preload. Again a wide range of recommendations, most between .020 to .060, with a few outside of that but no rational behind why. Some vague talk about rpm ranges, varying thermal expansion of the involved parts and valve train noise, but again, no details. Rpm range on my cam is 1500-6500 and I intend to use every bit of it on a fairly regular basis for autocross, road courses & street duty. I lean towards the performance end of the spectrum if that helps anyone in answering.
3. Is there a torque for the adjuster jamb nuts? Use of thread locker on adjuster/jamb nut?
4. What is the correct way to determine length for ordering a ball/cup pushrod? End of ball to top of cup or subtract 1/2 of adjuster ball diameter to get end of ball to bottom of cup? Or let the supplier figure it out?
5. Pros/cons of 5/16" pushrod vs bigger diameter for 6500 rpm range?
Thanks in advance guys and let's keep the "discussions" civil please.
So, riddle me this Batman (you know your old if you understood that!!):
1. Adjuster threads. Recommendations ranged anywhere from 1 to 4 threads showing after preload is set. I have not been able to find on-line what Crane actually specifies, if they do. I stared at my valve train for quite a while yesterday trying to figure out what difference it makes. Why does there need to be any threads showing? My guess is geometry but I thought up many reasons; optimized oiling of the ball & cup, adjuster strength, pushrod cup to rocker/spring retainer to rocker interference, manufacturer's design spec, ect..... My old pushrods, from my iron heads. result in the threads just begining to emerge, or 0 to maybe 1/2 thread showing on all rockers. I could find no binding issues anywhere and plenty of clearance everywhere. Can some of you more knowledgeable gents enlighten me on what the significance of # of threads showing results in, and why, so I can justify to myself the expense of new pushrods?
2. Preload. My old pushrods, with 0-1/2 thread showing, is with 1/2 turn on the adjuster which supposedly = .030 preload. Again a wide range of recommendations, most between .020 to .060, with a few outside of that but no rational behind why. Some vague talk about rpm ranges, varying thermal expansion of the involved parts and valve train noise, but again, no details. Rpm range on my cam is 1500-6500 and I intend to use every bit of it on a fairly regular basis for autocross, road courses & street duty. I lean towards the performance end of the spectrum if that helps anyone in answering.
3. Is there a torque for the adjuster jamb nuts? Use of thread locker on adjuster/jamb nut?
4. What is the correct way to determine length for ordering a ball/cup pushrod? End of ball to top of cup or subtract 1/2 of adjuster ball diameter to get end of ball to bottom of cup? Or let the supplier figure it out?
5. Pros/cons of 5/16" pushrod vs bigger diameter for 6500 rpm range?
Thanks in advance guys and let's keep the "discussions" civil please.