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oh no another pushrod question!!

This is a discussion on oh no another pushrod question!! within the Internal Engine forums, part of the LSx Technical Help Section category; I hate to keep blowing up this forum like this but yall seem to know your stuff. Im want to ...

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    oh no another pushrod question!!

    I hate to keep blowing up this forum like this but yall seem to know your stuff. Im want to check my pushrod length and ive read a few of the other threads on this but i cant find a good clear how to. I read the one in the sticky by Hi_Po but it kinda seemed fuzzy to me. Do i need the adjustable pushrod from comp or can i do it with the Stock 7.4 using the EO/IC method. its all just confusing.

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    Any other method than using an adjustable pushrod is just guess work. How you check your pushrod length is get the cylinder you are checking to TDC. Then loosen one of the rockers on that cylinder. Next lay a pushrod next to the checker and adjust it so they are the same size. Install the checker instead of the pushrod and tighten the rocker up. Pull up on the needle and if it barely makes a tap sound you are all set. If it doesn't move at all your length is too tall. Also if it makes a clear tapping sound your pishrod is too short. Now you adjust it up or down depending on the results of the test with stock length until you achieve that faint tap sound. Once you have achieved the proper length count the turns until fully closed. Now you take the number of turns and multiply it by .050 and add it to 6.8. This gives you zero lash length. For stock lifters you want around .070 to .075 prelod so you would add it to that value which will give you your length.

    So for example if it took 9 turns to fully close the checker this is what your length would look like: 6.8+9.0x.050+.075=7.325

    Let me know if you have any questions.
    Last edited by 98TransAmWs-6; 12-20-2013 at 12:41 PM.
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    oh no another pushrod question!!

    http://www.ls1.com/forums/f7/my-6-liter-build-174257/

    http://www.ls1.com/forums/f8/my-8-8-rear-build-165553/

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    well when the tool gets here i run my numbers by you just to double check

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    Quote Originally Posted by black04gto View Post
    well when the tool gets here i run my numbers by you just to double check
    Sounds good.

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    if i did my math right and this is purely number based havent measured it yet. but my heads are milled to 60cc, and being as they are ls6 style and have 64cc stock they only milled ~.028 and since its a ls6 style head the valve angle should stay the same 15* . so based on that logic my pushrods should be too long. This would explain the slight amount of oil loss over time and the small amount of oil i found in the headers today during a gasket change. Am i understanding this correctly?

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    Moderator 98TransAmWs-6's Avatar
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    Quote Originally Posted by black04gto View Post
    if i did my math right and this is purely number based havent measured it yet. but my heads are milled to 60cc, and being as they are ls6 style and have 64cc stock they only milled ~.028 and since its a ls6 style head the valve angle should stay the same 15* . so based on that logic my pushrods should be too long. This would explain the slight amount of oil loss over time and the small amount of oil i found in the headers today during a gasket change. Am i understanding this correctly?
    Too short not long. They milled material so you would need a longer pushrods. Other than that technicality you are spot on with your understanding.

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    im confused. its my understanding that when they mill heads the take material off the head deck therefore making the head shorter and closer to the piston thus the compression increase. if that holds true the rockers would be closer to the cam therefore requiring shorter rods. where am i wrong at??? just trying to grasp a better understanding.

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    Quote Originally Posted by black04gto View Post
    im confused. its my understanding that when they mill heads the take material off the head deck therefore making the head shorter and closer to the piston thus the compression increase. if that holds true the rockers would be closer to the cam therefore requiring shorter rods. where am i wrong at??? just trying to grasp a better understanding.
    Sorry I read what you said wrong. Yes too long is what your pushrods are if your heads were milled.

    Now if you switched to 72cc heads your pushrods would be too short. For me when I switched to 243 heads with no milling I needed shorter pushrods.
    Last edited by 98TransAmWs-6; 12-23-2013 at 02:45 PM.

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