5.3 advice

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05-28-2015, 11:36 AM

#21

Jeebalow

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Quote:

Originally Posted by JL Sargent

Also your cam base circle comes into play here. My factory cams base circle measured 1.560" while my new Comp Cam 212/218 cam measured 1.480". So if my math is right, the new setup will need .080" more push rod length right off the bat.

The pushrod length checker is used with the new cam in place so you don't have to do any math other than that in the post above. No need to complicate things.

BTW that .080" is a difference in diameter which will come out to .040" in pushrod length.

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05-28-2015, 12:10 PM

#22

bobfig

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Quote:

Originally Posted by Jeebalow

The turns to preload method does not work. Don't use that method. Use a push rod length checker like you are. That is the only way to accurately get a preload measurement. 7.325" seems fine. Here is a post that explains how to use the checker in case you need it.

correct pushrod length - LS1TECH

why wouldn't the turn method not work?

all it dose it count how many turns till 22 ft/lb and for every turn according to the thread pitch is .047" of movement. so for 2 turns its preloading the lifter .094" no matter what push rod you have.

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05-28-2015, 12:48 PM

#23

JL Sargent

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"BTW that .080" is a difference in diameter which will come out to .040" in pushrod length."

Good point. Thanks.

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05-28-2015, 03:22 PM

#24

Jeebalow

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Quote:

Originally Posted by bobfig

Because the bolt movement by turning the bolt is not equal to the pushrod movement. The pivot point of the rocker in this case would be the valve tip and that is on the other end of the rocker. The bolt is also not centered between valve and pushrod since the rockers are 1.7 ratio. Even if you did calculate the exact conversion using some trig, the bolt threads aren't perfect and have some tolerance to them. The rocker also isn't perfect so the valve doesn't touch the exact same spot on the rocker for each rocker which would change your lengths. Tightening a bolt to a specified torque value is also very highly dependent on materials, friction, thread condition, etc. There's lots of things that come into play.

I am also not the only one that thinks this.

Quote:

Originally Posted by Atomic

The turn method **** might be the worse thing to have come about in the ls world. It is not accurate, even if some claim it has been succesfull. Stock lifters are relatively forgiving, so ballpark is usually close enough for that crap to work.

Watching the valves like you did only works if your cam has exactly 0 overlap.

Buy the pushrod checker.

This quote from Texas Speed is in response to Atomic saying he doesn't like the bolt turns method.

Quote:

Originally Posted by Sales3@Texas-Speed

Although measuring that way can give you a round about idea of what length might get you close, I will have to agree with you 100%!

The above quotes came from these threads respectively if you want more context.
https://www.performancetrucks.net/fo...8/#post5247763
https://www.performancetrucks.net/fo...4/#post4982433

Last edited by Jeebalow; 05-30-2015 at 10:00 AM.

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05-30-2015, 09:57 AM

#25

madracer402

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The link from ls1tech is how i did it the first time. It might sound dumb but being that this is my first time doing this i tried 2 different methods and came up with the same measurement ..

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06-02-2015, 05:44 PM

#26

madracer402

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As im sitting here with the swap all done and just waiting on my ecm to return does anybody know if I can use a ecm out of a 06 silverado 2500 (6.0)..I just want to get power to the motor kick the fuel pump on and check some wiring?? Im not going to turn the motor over because I know one is drive by wire tb and the other is cable tb and figured that would cause issues..

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