zero lash....dummy question
zero lash....dummy question so is zero lash on the lifter when the pushrod just comes into contact with the lifter, and the rocker is on the valve...basically so theres no space between them (except for when you push the lifter in obviously).
or is it when the pushrod gets hard to spin (obviously lifter going down a little).
im going to get a pr length checker, and check length too...
or is it when the pushrod gets hard to spin (obviously lifter going down a little).
im going to get a pr length checker, and check length too...
Yes, that is zero lash. Need to use a light touch w/ the rocker bolt in finding the point at which there is no lash or play in the valvetrain.
ok. so i guess my pushrods are way too long then. at that point... to tighten to 22ft. lbs it takes about 3 turns...so thats like .160 pre load.
im getting a checker.
also...head question. can anyone confirm that tsp's stage ones come with the valves deeper in the head...when setup for an ms4 cam? guy i got them from said he used 7.4 pushrods. pat g reccomended 7.425. but im thinking now i need like a 7.350
does it change anything that i soaked the lifters in oil for about a day???
im getting a checker.
also...head question. can anyone confirm that tsp's stage ones come with the valves deeper in the head...when setup for an ms4 cam? guy i got them from said he used 7.4 pushrods. pat g reccomended 7.425. but im thinking now i need like a 7.350
does it change anything that i soaked the lifters in oil for about a day???
ok. just used the EO/IC method. knowing that for every turn of the rocker bolt gives me .047 preload. they reccomend 1 1/4 to 1 3/4 turns. i came up with 2 turns. so basically right now i have .094 preload. which is a little much.
anyone reccomend me going ahead and running that much preload on the ls7 lifters??? or no? i could get a 7.4 pushrod and be at .070 preload...
anyone reccomend me going ahead and running that much preload on the ls7 lifters??? or no? i could get a 7.4 pushrod and be at .070 preload...
yeah thats what im thinking....im going to buy some 7.4's
im getting numbers from .088-.094 preload right now. ive read of people running up to .120...which i think is a lot. i see most operating around .06-.08
im getting numbers from .088-.094 preload right now. ive read of people running up to .120...which i think is a lot. i see most operating around .06-.08
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wow! thanks for brining that up. i was thinking the same thing how actually torquing the bolt applies no preload. maybe im good then.
but i did it right. basically spin (count spins) from zero lash to when the rocker bottoms out. right now im at 1 7/8 of a turn (no torque applied)
so my math says: (7/8)x.047=.0411 + .047 = .088 preload.
or 1 7/8x .047=.088 preload
this based off my math.....
but then using the math from that post.... 1.875(1 7/8 turns) x 1.25/25.4 x 2.7/1.7 i get.... .146 preload sooooo...
guess im in need of a 7.350 pushrod... .075 shorter than what i have now put me at .071 preload
so im actually at about 2.2 turns from zero lash to full torque. but my preload is measured correctly based on spins from zero lash to the rocker bottoming out and that it will be .047 preload per turn.
but i did it right. basically spin (count spins) from zero lash to when the rocker bottoms out. right now im at 1 7/8 of a turn (no torque applied)
so my math says: (7/8)x.047=.0411 + .047 = .088 preload.
or 1 7/8x .047=.088 preload
this based off my math.....
but then using the math from that post.... 1.875(1 7/8 turns) x 1.25/25.4 x 2.7/1.7 i get.... .146 preload sooooo...
guess im in need of a 7.350 pushrod... .075 shorter than what i have now put me at .071 preload
so im actually at about 2.2 turns from zero lash to full torque. but my preload is measured correctly based on spins from zero lash to the rocker bottoming out and that it will be .047 preload per turn.
Last edited by zacht; Aug 4, 2011 at 10:00 PM.
can anyone confirm my math here? i have 1 7.8 turn til the rocker bottoms out...so im thinking .047 per turn puts me at .088...but when i put it into that guys formula it says .146....im thinking the math he has isnt working for me. im thinking im at .088...
or someone call me stupid and that i should order a pushrod length checker already...lmao..
or someone call me stupid and that i should order a pushrod length checker already...lmao..
Last edited by zacht; Aug 4, 2011 at 11:48 PM.
NOTE: My post is corrected because as pointed out in post 13 I missed the fact that the turns counted were from zero lash to rocker bottoming rather than 22 lb-ft of torque on the bolt.
Based on my experience with my motor, 1/3 turn is required after the rocker bottoms to reach torque but since you are counting from zero lash to rocker bottom the numbers you have are correct.
My only concern is Pat G is usually pretty accurate with his recommendations and the math says use a 7.375" pushrod. Might be worth double checking and if you haven't bought pushrods yet get an adjustable pushrod and verify the length so you only buy one set of pushrods.
Based on my experience with my motor, 1/3 turn is required after the rocker bottoms to reach torque but since you are counting from zero lash to rocker bottom the numbers you have are correct.
My only concern is Pat G is usually pretty accurate with his recommendations and the math says use a 7.375" pushrod. Might be worth double checking and if you haven't bought pushrods yet get an adjustable pushrod and verify the length so you only buy one set of pushrods.
Last edited by vettenuts; Aug 5, 2011 at 01:24 PM.
On The Tree
Joined: May 2011
Posts: 157
Likes: 2
He's at 1.875 turns before applying any torque, so you would have to add 1/3 not subtract it. Either way, IMO, he should be doing his calculating at full 22 ft/lbs. Guessing that it's at 0 torque, subsequently would be guessing at actual preload without an indicator on the rocker.
I'm having a tough time trying to understand why the above formula is using the 1.7 rocker ratio though. In my mind, the determining factor for preload wouldn't be the valve tip side, but the pushrod seat side. The 1.7 ratio is the relationship between the CL of the trunnion to the CL of the tip vs. the CL of the trunnion to the CL of the pushrod seat. Being that on all rockers, the pushrod seat side ratio is 1, I wouldn't think it's a factor for preload equations. Maybe I'm over thinking this though haha. I always use adjustable rockers due to my short travel lifters, so I have to measure with a checker and indicator.
I'm coming up with .049/turn using a M8x1.25 bolt (1.25/25.4). So at .049 x 1.875 = .0918 preload.
Anyway, OP, get you a pushrod checker and check your wipe pattern. Measure the length and order up some pushrods that are closest. There are too many deviations in deck height, head thickness, lifter extended lengths, etc etc etc to not use a checker.
I'm having a tough time trying to understand why the above formula is using the 1.7 rocker ratio though. In my mind, the determining factor for preload wouldn't be the valve tip side, but the pushrod seat side. The 1.7 ratio is the relationship between the CL of the trunnion to the CL of the tip vs. the CL of the trunnion to the CL of the pushrod seat. Being that on all rockers, the pushrod seat side ratio is 1, I wouldn't think it's a factor for preload equations. Maybe I'm over thinking this though haha. I always use adjustable rockers due to my short travel lifters, so I have to measure with a checker and indicator.
I'm coming up with .049/turn using a M8x1.25 bolt (1.25/25.4). So at .049 x 1.875 = .0918 preload.
Anyway, OP, get you a pushrod checker and check your wipe pattern. Measure the length and order up some pushrods that are closest. There are too many deviations in deck height, head thickness, lifter extended lengths, etc etc etc to not use a checker.
Last edited by Havoc40; Aug 5, 2011 at 01:01 PM.
He's at 1.875 turns before applying any torque, so you would have to add 1/3 not subtract it. Either way, IMO, he should be doing his calculating at full 22 ft/lbs. Guessing that it's at 0 torque, subsequently would be guessing at actual preload without an indicator on the rocker.
I'm having a tough time trying to understand why the above formula is using the 1.7 rocker ratio though. In my mind, the determining factor for preload wouldn't be the valve tip side, but the pushrod seat side. The 1.7 ratio is the relationship between the CL of the trunnion to the CL of the tip vs. the CL of the trunnion to the CL of the pushrod seat. Being that on all rockers, the pushrod seat side ratio is 1, I wouldn't think it's a factor for preload equations. Maybe I'm over thinking this though haha. I always use adjustable rockers due to my short travel lifters, so I have to measure with a checker and indicator.
I'm coming up with .049/turn using a M8x1.25 bolt (1.25/25.4). So at .049 x 1.875 = .0918 preload.
Anyway, OP, get you a pushrod checker and check your wipe pattern. Measure the length and order up some pushrods that are closest. There are too many deviations in deck height, head thickness, lifter extended lengths, etc etc etc to not use a checker.
I'm having a tough time trying to understand why the above formula is using the 1.7 rocker ratio though. In my mind, the determining factor for preload wouldn't be the valve tip side, but the pushrod seat side. The 1.7 ratio is the relationship between the CL of the trunnion to the CL of the tip vs. the CL of the trunnion to the CL of the pushrod seat. Being that on all rockers, the pushrod seat side ratio is 1, I wouldn't think it's a factor for preload equations. Maybe I'm over thinking this though haha. I always use adjustable rockers due to my short travel lifters, so I have to measure with a checker and indicator.
I'm coming up with .049/turn using a M8x1.25 bolt (1.25/25.4). So at .049 x 1.875 = .0918 preload.
Anyway, OP, get you a pushrod checker and check your wipe pattern. Measure the length and order up some pushrods that are closest. There are too many deviations in deck height, head thickness, lifter extended lengths, etc etc etc to not use a checker.
As for the rocker correction, the valve stem is fixed (or you have to think of it that way because the valve must be closed on the base circle). If you tighten the bolt, the pushrod end must move further then the bolt so parallel triangles are used to figure out the amount the pushrod moves with bolt movement. That is where the "2.7/1.7" correction comes from. If you figure the ratio is 1.7, then the distance the pushrod moves is multiplied by 1.7 at the valve. So if you figure a nominal distance from pushrod to bolt as 1, the distance to the valve stem is 1.7. Therefore, the distance from the valve stem back to the bolt is still 1.7 but the distance to the pushrod is 1.7+1, or 2.7 because when tightening you are pivoting at the valve stem.
Hope that makes sense.
On The Tree
Joined: May 2011
Posts: 157
Likes: 2
Ok, that does make perfect sense. I wasn't picturing the valve "fixed". Thanks for the info and my brain teaser for the day! Never really put much thought into it. When you play with as many lifter combinations as I do, worrying about rocker ratios and threads per inch is pointless. When using an indicator anyway.
(1.875+.3333).049*2.7/1.7=.173 preload.
(1.875+.3333).049*2.7/1.7=.173 preload.
ok. but what im saying is by doing the math...i need a 7.350 pushrod. but by using shane's method says i need a 7.4 pushrod.
ive got a checker coming. ill be able to check the wipe pattern and all...
ive got a checker coming. ill be able to check the wipe pattern and all...
Using shanes methods it sounds like you have two turns from zero lash to 22 lb-ft. If thats the case, then his method is telling you almost exactly the same thing as the math.
