Checking pushrod lenght
11-03-2009, 04:56 AM
#21
I don't know why you don't believe Shane, the procedure he uses works great. I checked mine with a pushrod checker (sucks getting your figures in there to turn it accurately) and then I used his method and came up with 7.370 for mine.
This is from Yella Terras Site by the way.
Do roller rockers need special push rods?
Usually no, with the exceptions being:
1. When screw-in studs and hardened guide plates are to be fitted (on engines not fitted with them originally). These need hardened pushrods.
2. When extremely heavy valve springs are fitted a more robust push rod than standard may be required.
What tappet settings do I use when fitting roller rockers?
Whether using Roller Rockers or standard rockers, the tappet settings remain the same as specified for your camshaft.
This is from Yella Terras Site by the way.
Do roller rockers need special push rods?
Usually no, with the exceptions being:
1. When screw-in studs and hardened guide plates are to be fitted (on engines not fitted with them originally). These need hardened pushrods.
2. When extremely heavy valve springs are fitted a more robust push rod than standard may be required.
What tappet settings do I use when fitting roller rockers?
Whether using Roller Rockers or standard rockers, the tappet settings remain the same as specified for your camshaft.
11-03-2009, 07:56 PM
#23
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Thanks for all the responses. My setup is LS7 lifters, TSP Torquer v.2 232/234 .595/.598 112 cam, 799 heads milled 0.015, stock rockers, GM head gaskets. I've gone and made measurements and with pushrod checker I get 7.280, I've also used the torqueing method and I get about ~1 5/8 turn before reaching 22lbs torque using a 7.4 pushrod. Now if I'm understanding correctly using the torque method the 7.4's are ok? (1 1/4 to 1 3/4 turns) and with the checker looking for a pushrod between .050 to .080 preload would mean I need a 7.350 pushrod. I'm not clear as to what to do right now.
Grip pushrod between fingertips and turn, then slowly tighten rocker bolt. When you start to feel resistance on the pushrod, count turns till fully torqued. If you had 1 5/8 turns on the bolt with 7.4" pushrods, they will be fine. Still in 1 1/4 to 1 3/4 turn range. Hope this helps, Dean
edit: The lifter must be on the base circle of the cam. You don't have shaft rockers do you?
11-04-2009, 04:40 AM
#24
Looks to me that your measured value is correct. If you check with the 1-5/8 turns (assuming that the bolt hasn't been turned past rocker bottoming), the preload I come up with is 0.127" with the 7.400" pushrod. If you reduce the pushrod by 0.050" to a 7.350" then the preload should come down to 0.077" which is in the range you are looking for. I would favor your direct measurement with the adjustable pushrod.
Last edited by vettenuts; 11-04-2009 at 06:44 PM.
11-04-2009, 07:44 PM
#25
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Looks to me that your measured value is correct. If you check with the 1-5/8 turns (assuming that the bolt hasn't been turned past rocker bottoming), the preload I come up with is 0.127" with the 7.400" pushrod. If you reduce the pushrod by 0.050" to a 7.350" then the preload should come down to 0.077" which is in the range you are looking for. I would favor your direct measurement with the adjustable pushrod.
11-05-2009, 04:43 AM
#26
The only time lifter preload is developed is between zero lash and when the rocker bottoms on the rocker stand. Any further bolt rotation used to achieve the final torque value is loading the bolt and the joint, which won't further change the lifter preload. For example, if you tighten the bolt to 22 lb-ft or 50 lb-ft, it will not change the preload any significant amount but the bolt rotation will change. There are a lot of variables in this method, the adjustable pushrod is much more accurate if done correctly.
The bolt rotation method works well on stud mounted rockers because the rocker doesn't bottom against anything, but on shaft mounted rockers you should use a dial indicator rather then bolt rotation and torque.
The bolt rotation method works well on stud mounted rockers because the rocker doesn't bottom against anything, but on shaft mounted rockers you should use a dial indicator rather then bolt rotation and torque.
