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Need help! 5.3 running like crap after cam swap

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Old Jan 21, 2016 | 05:25 PM
  #31  
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Let's keep the issue in 1 thread. Thanks
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Old Jan 21, 2016 | 07:30 PM
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Have you pulled a plug wire off of a plug to make sure you are getting spark to the plug???? I would think pushrod length would affect all cylinders not just one bank...
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Old Jan 23, 2016 | 05:17 PM
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Originally Posted by 1FastBrick
Have you checked compression???

I would bet its a mechanical issue such as push rod length.
I think you're right about the push rods.
I finally was able to do the compression test and i found out only 2 of 8 cylinders have compression.
so i took a look at my push rods and noticed that they were too long and were keeping my valves from closing all the way. Rookie mistake I guess...next step is to get a checker tool
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Old Jan 25, 2016 | 01:59 AM
  #34  
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Originally Posted by Wolftrk99
Have you pulled a plug wire off of a plug to make sure you are getting spark to the plug???? I would think pushrod length would affect all cylinders not just one bank...
Not necessarily. Core shift can affect it from 1 side to the other as well as front to back.

Originally Posted by Antsilver
I think you're right about the push rods.
I finally was able to do the compression test and i found out only 2 of 8 cylinders have compression.
so i took a look at my push rods and noticed that they were too long and were keeping my valves from closing all the way. Rookie mistake I guess...next step is to get a checker tool
It's generally a good Idea to check even with a small cam. Ran into this same issue with a friend and a reground camshaft.
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Old Jan 25, 2016 | 11:03 AM
  #35  
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Yes I did check for spark and fuel and both were fine. It turns out that only 2 cylinders were getting compression and when i the check the push rods I saw that there was too much preload on the lifters (2.5 turns once it was at zero lash) therefore not allowing the valve to close all the way. Not sure why the number 1 and 3 were still getting compression but it's obvious that the push rods are too long.
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Old Jan 25, 2016 | 12:03 PM
  #36  
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What length pushrods are you using??
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Old Jan 25, 2016 | 12:42 PM
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They are stock, 7.400 I believe.
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Old Jan 25, 2016 | 01:22 PM
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invest in a 20$ pushrod length checker. the turn method is a crapshoot.
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Old Jan 25, 2016 | 01:53 PM
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Already on order
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Old Jan 27, 2016 | 10:34 AM
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My .02.

What lifters did you use? Were they installed correctly in the trays?

With the cam you selected, you should be able to use the 7.4's fine.

Someone told me a long time ago,

Zero compression - rings/stuck valve issue

Low compression - other issue (valve not opening all the way, collapsed lifter(s))

Hope you get it figured out but I think you'll be tearing it down again.
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