Pushrods are too long
TECH Regular
Joined: Jul 2011
Posts: 452
Likes: 2
How do you know you need 7.325 pushrods if you haven't measured?
What lifters are you running? ... different lifters have different pre-load settings. See attached chart.
You're talking 0.075" difference between what you think you need and what you have. If you are running LS7 lifters, you might get away with it for a while since they have lots of plunger travel.
Pushrod length checker. 9.5 turns. 0.50 preload needed for Lunati linkbar lifters. Checked EO/IC and also at 45-degrees past intake closed. Checked four cylinders. Pretty confident in results. They were all 6.80 + 9.5x0.050 + 0.050 = 7.325".
I don't know why you have 7.4" installed when you know 7.325" is needed, but I don't care. It would be nice, not to mention helpful, for someone that knows to answer your question, not question you. Knowing its off .075", I wouldn't run it at all until I know for certain if its ok or not.
TECH Regular
Joined: Jul 2011
Posts: 452
Likes: 2
He also now divulged that his zero lash measurement with adjustable pushrod is "6.80 + 9.5x0.050", which gives a zero lash pushrod length of 7.275". If he's running 7.400" pusrods, then his pre-load is 7.400 - 7.275 = 0.125".
So ... if the total travel on these Lunati lifters is somewhat larger than 0.125", then he's probably not bottoming them out but could be close. If he had LS7 lifters, then he'd be safer for now since they have a total plunger travel of 0.166".
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Just finished buttoning-up my new top end and would like to start trying to tune it or at least see how it runs. Will order the right-size pushrods today, but have had a few setbacks and would like to get this thing running. Am anxious, but not reckless.
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Verdad Gallardo TECH Regular
Joined: Jul 2011
Posts: 452
Likes: 2
Expect to hear some lifter noise until they get fully pumped up. But yes, try to find out what the plunger travel is on those lifters before starting just to be sure you're not already bottoming out the lifter with your 0.125" pre-load.
i wouldnt take a chance personally
if the valves are to big youll totally bottem everything out.
too big of a risk if you ask me.
better to do be patient the first time.
or youll be waiting even longer the second time around.
if the valves are to big youll totally bottem everything out.
too big of a risk if you ask me.
better to do be patient the first time.
or youll be waiting even longer the second time around.
On The Tree
Joined: Oct 2011
Posts: 132
Likes: 0
From: 20 minutes from the Valley...
OP, it's probably not in best interest to see if the wrong piece will work or "be ok". I think you should be patient and do what you know is right the first time. Good luck either way.
Thanks for all of the replies. I will wait until the 7.325" pushrods are installed before starting and running it. I did everything else to the best of my ability on this build, so it would make no sense to try something that would possibly damage my engine.
