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pushrod length? I know again.. any help

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  1. #1
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    pushrod length? I know again.. any help

    OK I could use some help, stock motor 1998? Bought it with 50,000 on it, swapped out cam this winter 228r with 7.4 pushrods and 650 springs TSP stuff.
    I have a ticking a lower RPMs seems to come from the valvetrain sounds like a bent pushrod in an old school SBC, just not as loud. I can hear it best when next to a building or listening low on the front fenders. Checked my pushrod length today with comp cam tool. Found it to read 10 turns to zero lash that would be a 7.3 with no preload right? I thought I would find the opposite, I thought I would need a longer pushrod 7.425. But this check says with preload I would need the 7.350 pushrods. @#$%^&*???
    I rolled the two pushrods I removed, on a sheet of glass and one seems to be just a little bent very little. This is on a 1998 car would that make a difference? Hope someone can help I would hate to spend the money on the pushrods and be wrong. The TSP 7.4 equal out to right close to 7.375ish when I measured them doesn’t seem like much.. Any help thanks

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    Quote Originally Posted by seweber View Post
    OK I could use some help, stock motor 1998? Bought it with 50,000 on it, swapped out cam this winter 228r with 7.4 pushrods and 650 springs TSP stuff.
    I have a ticking a lower RPMs seems to come from the valvetrain sounds like a bent pushrod in an old school SBC, just not as loud. I can hear it best when next to a building or listening low on the front fenders. Checked my pushrod length today with comp cam tool. Found it to read 10 turns to zero lash that would be a 7.3 with no preload right? I thought I would find the opposite, I thought I would need a longer pushrod 7.425. But this check says with preload I would need the 7.350 pushrods. @#$%^&*???
    I rolled the two pushrods I removed, on a sheet of glass and one seems to be just a little bent very little. This is on a 1998 car would that make a difference? Hope someone can help I would hate to spend the money on the pushrods and be wrong. The TSP 7.4 equal out to right close to 7.375ish when I measured them doesn’t seem like much.. Any help thanks
    Without actually being there its kind of hard to understand exactly whats going on lol. But if you use this method it should give you a good solid idea....

    1.Take your comp tool and set it to the stock length of 7.4

    2. Install the tool, set the rocker to 0 lash, then torque the rocker down to 22 ft lbs and count the turns as you go.

    3. One full turn on the bolt is ~.047 preload and with stock type lifters you want about .080

    4. Shooting for .080 preload you should get 1.5-1.75 turns from 0 lash to 22 ft lbs of torque.

    If you get less than that then adjust the push rod tool and try again do that until it is within spec....

  3. #3
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    7.4 TSP pushrods torqued to 22ft from zero lash gets me 1.75 turns. So with your method it sounds good if I need the .080 preload. Just trying to get the valvetrain as quiet as possible and also make sure everything is ok. I have driven on this cam for about 2500 miles and turned some good numbers, it just has this random ticking at low RPMs that many people have described. I have built many motors and a noise like this would not be tolerated, but this is my first LS motor. Some have suggested that I go for 0.050 preload which to me would be louder…?

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    Quick update I checked with summit racings tech line when ordering my pushrods, they recommended I check pushrod preload with a dial indicator, before I buy. So I installed the 7.4 pushrods again (getting pretty fast at it now), set them to zero lash and installed the dial indicator on the rocker at the oil hole, then torqued to 22 ft. I found only 0.050- 0.060ish preload on the lifter…. I checked all the rockers on the odd side of the engine plus 2 and 4 on the other, before I was satisfied. Placed a call and ordered a set of 7.425 and installed them (really fast now, like a pit crew).
    Started motor, valve train sounds like it did when stock, typical sewing machine. I have not taken it to the track yet. I put about 250 miles on it last week, and drove in heavy traffic and hot weather yesterday. All still sounds good.

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