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Old 03-22-2006, 10:42 PM
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Default MS3 setup

Im doing the MS3 PRC dual spring kit, which size PR's should I get stocklength? some guy earlier said to do 7.350? I am not sure on the size exactly but I think he said a shorter than stocklength. Anyway I was looking for less valvetrain noise, and if you recommend shorter or larger Pr's then stock, whats benefits/setbacks. I just dont want a realllly noisey valvetrain. thanks!
Old 03-22-2006, 10:44 PM
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7.425 is the ideal setup for that cam from what I have searched on here.

I run the 7.400 PR'S with my MS3 and it is very noisy
Old 03-22-2006, 10:44 PM
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If the only thing you are changing is the springs, why do you want different length pushrods then what you have already?
Old 03-22-2006, 10:59 PM
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Originally Posted by heavymetals
If the only thing you are changing is the springs, why do you want different length pushrods then what you have already?

So they dont break, and go flying out the side of the block.

Last edited by MRZ28; 03-22-2006 at 11:05 PM.
Old 03-22-2006, 11:06 PM
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I don't know how you equate length to tensile strength, but whatever.
Old 03-23-2006, 01:11 AM
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I want to know why TSP puts 7.4's in the package if that cam needs 7.425's.
Old 03-23-2006, 09:22 AM
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Originally Posted by Robinator
I want to know why TSP puts 7.4's in the package if that cam needs 7.425's.
thats what i want to know as well, i just put that cam in with 7.400 pr and it's noisey as hell and the guys at the shop told me that i need 7.425 pr and then there will be no noise so i ordered some and there on backorder wich sucks.
Old 03-23-2006, 06:59 PM
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ive got 7.425's in mine and its extreamly quiet, its quieter than it was stock
Old 03-23-2006, 07:09 PM
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i was also told stock 7.4 pushrods for my ms3 setup. Hmmmm
Old 03-23-2006, 08:12 PM
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with the longer pushrods, do you have to worry about compressing(or colapsing) a lifter? Do they give us 7.4's for a reason?
Old 03-30-2006, 02:09 AM
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Stick with the 7.400". I have the same setup and went with the 7.425" push rod. I found out last night that it is bleeding off cylinder pressure because they are too long. The reading with the 7.425 was 130 psi. I put in a shorter set and it jumped to 170 psi. Most aggressive cams will make valve train noise.
Old 03-30-2006, 02:12 AM
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Originally Posted by heavymetals
If the only thing you are changing is the springs, why do you want different length pushrods then what you have already?
The real reason for longer pushrods is because the base circle on most aftermarket cams is smaller than stock. It is also a good idea to go to a hardened one with the much higher spring pressures.
Old 03-30-2006, 02:35 PM
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OK first i hear use 7.425's to make it quiet, then i see use 7.4's so it wont bleed off pressure. I take it there is no pushrod that s between these lengths to find a happy medium.
Old 03-30-2006, 02:38 PM
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I say just put-up with the noise
Old 03-30-2006, 02:39 PM
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would that noise cause KR
Old 03-30-2006, 02:51 PM
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I haven't heard of anyone ever having Knock Retard on a properly installed cam
Old 03-30-2006, 02:52 PM
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the only reason mine was so loud at first was a header leak. It sounds like a champ now! I will see if I can post a video here in the next week or so.
Old 03-30-2006, 02:52 PM
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Originally Posted by NXZ28
Stick with the 7.400". I have the same setup and went with the 7.425" push rod. I found out last night that it is bleeding off cylinder pressure because they are too long. The reading with the 7.425 was 130 psi. I put in a shorter set and it jumped to 170 psi. Most aggressive cams will make valve train noise.
For 1 that is BS,

Your sig says aftermarket heads, were they milled?
What gasket are you running?

Here try this calc for a rough idea, on cam only swaps with stock gaskets 7.425 are it.

http://ourworld.cs.com/ls1info2/Pushrod+calculator.xls

Last edited by PREDATOR-Z; 03-30-2006 at 03:10 PM.
Old 03-31-2006, 01:36 AM
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Originally Posted by PREDATOR-Z
For 1 that is BS,

Your sig says aftermarket heads, were they milled?
What gasket are you running?

Here try this calc for a rough idea, on cam only swaps with stock gaskets 7.425 are it.

http://ourworld.cs.com/ls1info2/Pushrod+calculator.xls
No BS. When I had the XER lobe cam I could not get it quiet for nothing. It always made some noise. The computer did not retard any timing though. My MS3 cam is quiet but it bleeds off cylinder pressure and leaves alot of HP on the table. I can live with a little noise. I am putting in a set of 7.400" pushrods this weekend. I will let you know what it does. I have the Patriot Stage II LS6 Heads that are not milled. I used stock GM head gaskets.

Last edited by NXZ28; 03-31-2006 at 01:57 AM.
Old 03-31-2006, 03:54 AM
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For a pushrod to be too long to hang a valve open and bleed pressure, believe me that it would be more than .025" too long
Think about it, that would mean that your lifters are overpowering your springs and opening the valve.
Something else is not kosher.



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