Preload.. 1 turn = .047" is this really accurate?
I tell you what. It's a little bit harder to use an adjustable pushrod on an LS motor than an Gen I or II engine.
I mis spoke about the pushrod length. I posted earlier based off memory which was wrong. 9 turns for the intake and 9 1/4 turns for the exhaust.
9 turns x .050=.45
.45 + 6.8(length of pushrod) = 7.25
7.25 + .047 = 7.297
so a 7.3 push rod is right? I hope I explained myself better and the 1/2 turn on the rocker bolt was to make sure it was tight.
Last edited by LilJayV10; Jun 23, 2010 at 08:31 AM.
After working at the shop all day I worked on the engine tonight.
I used the 1 1/2 turns to preload. I did this about 4 times on the intake and exhaust, starting at the factory 7.4 and working my way down.
I got 7.35 for the intake and 7.325 on the exhaust.
One thing I learned tonight is when you are using an adjustable pushrod checker is to use tape. When I would set the adjustable pushrod to a certain length then try to find zero lash I always found myself "adjusting" the pushrod down some. After doing this a few times it came to me to put a piece of tape around it to hold it where I put it at.
On both the intake and exhaust I got the lengths at 1 1/4 turn at 22 ft lbs. Every time.
I am confident that these are the lengths I need. I left the light weight checker valve springs in to make sure I wasn't preloading the valve any.
Is the .025 difference worth buying two lengths of pushrods? Would the extra preload on the exhaust hurt anything?
At this point it doesn't matter if I buy two sets of pushrods. I am this far in it, doing things correctly, (as best I know of) that another hundred bucks isn't going to kill me.
I made sure one valve was all the way open and checked the closed one.
I used the 1 1/2 turns to preload. I did this about 4 times on the intake and exhaust, starting at the factory 7.4 and working my way down.
I got 7.35 for the intake and 7.325 on the exhaust.
One thing I learned tonight is when you are using an adjustable pushrod checker is to use tape. When I would set the adjustable pushrod to a certain length then try to find zero lash I always found myself "adjusting" the pushrod down some. After doing this a few times it came to me to put a piece of tape around it to hold it where I put it at.
On both the intake and exhaust I got the lengths at 1 1/4 turn at 22 ft lbs. Every time.
I am confident that these are the lengths I need. I left the light weight checker valve springs in to make sure I wasn't preloading the valve any.
Is the .025 difference worth buying two lengths of pushrods? Would the extra preload on the exhaust hurt anything?
At this point it doesn't matter if I buy two sets of pushrods. I am this far in it, doing things correctly, (as best I know of) that another hundred bucks isn't going to kill me.
I made sure one valve was all the way open and checked the closed one.
GM lifters are pretty forgiving with the preload. Unless you are very light or very deep the 0.025 shouldn't be an issue. What may net you a more stable valve train and a few ponies up top (it did for me) is a larger diameter pushrod. Are the heads on the car yet?
Yeah I finally got them bolted on two nights ago. I got pan, timing cover and some front accessories on last night. Once I get the pushrods I will ready to put it back in the car.
