Do I have enough lifter preload?
#1
Do I have enough lifter preload?
I just installed some TFS 215s on my SS tonight with the included 7.5 inch Trickflow pushrods & some new Yella Terra 1.7s, & GM MLS gaskets. Following YTs instructions, I finger tightened both #1 cyl rockers at TDC, then from there torqued them to 25 ft lbs, without shims. From finger tight to 25 ft lb it only took 1/4 turn. Their instructions say 1/4-1/2 turn is ideal, if more than 1 full turn use the shims. If I rock the rockers back & forth theres prolly .020 play. Now the heads were milled .010, & the LS7 lifters are new & submerged in fresh oil for a few days. Do you think its just the new lifters not being pumped up or should I get longer pushrods?
#3
After doing a search I found the LS7 lifters like a lot of preload, like .060, & from what I did tonight I only have .012 preload. From that, a 7.550 pushrod sounds about right. I do have a pushrod length checker tool & may play around with it tomorrow after work. Thanks though for the info.
#4
I went ahead & got the pushrod length checker tool out tonight & tried that. With the 7.5 pushrod it takes 1/4 turn to 22 ft lbs after finger tight. With the pushrod tool turned out 15 times(=7.550 inch) it takes almost 1 full turn to 22 ft lb from finger tight so I am gonna go with 7.550. I dont know why Trickflow recommends this 7.5 pushrod for their heads when theres so many variables.
#6
Staging Lane
Join Date: Jan 2009
Location: Fayetteville, NC
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hydraulic lifters need to be preloaded .045" to .075" to operate correctly however many racers in hydraulic classes will run as little as .010" with a hydraulic lifter that has a very stout retaining device to keep the plunger from pushing out the top of the lifter
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#9
The 7.550 pushrods did the trick. That gave me around .050 preload & a fairly quiet valvetrain after I let it warm up. The wipe pattern appeared to be good as well. After working on it for the last 4 days after work, I was anxious to get this thing fired up so I had them overnighted from Summit.