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help with getting pushrod size (VIDS)

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Old 06-07-2011, 02:22 PM
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Default help with getting pushrod size (VIDS)

Hey guys I need help please. So using my comp cams pushrod checker and following the link from vettesnut I measured a lil different from intake to exhaust. Maybe I did something wrong?

I'm on tdc using a lil flathead through the spark plug hole and turning the crank I'm as good on tdc as I can be, I put the rocker on intake and exhaust and snug it down and barely getting any up and down movement I got these readings using the formula at 0.075 preload
I:6.800+9.75x0.050=7.3...7.375
E:6.800+10.0x0.050=7.2875..7.3625

Did I do something wrong or should I just go 7.375 or can I add more preload and use 7.4?

Mods are 243 heads no milling with gm MLS gaskets. Ls7 lifters and eps 222/230 596/600 117+4

Thanks I'm out here putting her back together hopefully I can get a response asap.

Last edited by 408Maro; 06-21-2011 at 03:30 PM.
Old 06-07-2011, 05:23 PM
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Good question, I know PatG recommended 7.425 for me with EPS 226cam, LS7 lifters, PRC 2.5 LS6 unmilled GM MLS gaskets on my 02 C5. But I've seen a couple threads where 7.4 seemed to work best cuz the height of the pushrod cup offset the base circle difference once pre loaded correctly, or something like that. I'm nervous cuz I already paid quite a bit more for the 7.425's. Good luck I hope someone can help you get it right.
Old 06-07-2011, 05:27 PM
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Thanks he said 7.4 should be fine but wanted to measure to make sure. I have new 7.425 sitting aswell as 7.4 from the last set up but guess ill have to put on on maybe smaller? Hopefully we can both get our issues solved
Old 06-07-2011, 05:27 PM
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I'd just go 7.375" on both. The pushrods are typically available in .025" increments, and 7.375" is closer than 7.350" on that exhaust side (7.350" would also be a bit light on preload IMO).

I would NOT go as long as 7.400" on either side....and definitely not 7.425"!
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Old 06-07-2011, 05:38 PM
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So does the smaller base circle on 02 cams require a longer pushrod when using LS7 lifters?
Old 06-07-2011, 05:45 PM
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Originally Posted by hardcore4sure
So does the smaller base circle on 02 cams require a longer pushrod when using LS7 lifters?
02 cams? Do you mean LS6 cam? LS6 heads have a slightly taller valve stem to account for smaller base circle.

I agree with Matt, 7.375" looks like it should be good.
Old 06-07-2011, 05:46 PM
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Originally Posted by hardcore4sure
Good question, I know PatG recommended 7.425 for me with EPS 226cam, LS7 lifters, PRC 2.5 LS6 unmilled GM MLS gaskets on my 02 C5. But I've seen a couple threads where 7.4 seemed to work best cuz the height of the pushrod cup offset the base circle difference once pre loaded correctly, or something like that. I'm nervous cuz I already paid quite a bit more for the 7.425's. Good luck I hope someone can help you get it right.
7.425" will be too long for that combo!

Originally Posted by hardcore4sure
So does the smaller base circle on 02 cams require a longer pushrod when using LS7 lifters?
LS7 lifters will require about a .050" shorter pushrod than if you were using the stock LS1 lifters that came in a 4th gen F-body.
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Old 06-07-2011, 05:59 PM
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Thanks guys. Looks like ill be ordering 7.375 rods!! Hopefully all works out
Old 06-07-2011, 06:27 PM
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Originally Posted by Matt@Texas-Speed
7.425" will be too long for that combo!



LS7 lifters will require about a .050" shorter pushrod than if you were using the stock LS1 lifters that came in a 4th gen F-body.
Wow, ok so 7.350 or 7.375 is what I need? I'm really puzzled why PatG would recommend this length? I even double checked with him after I ordered the cam from EPS and Geoff asked why I was going with 7.425 instead of 7.4?
Old 06-07-2011, 09:43 PM
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Originally Posted by Matt@Texas-Speed
LS7 lifters will require about a .050" shorter pushrod than if you were using the stock LS1 lifters that came in a 4th gen F-body.
https://ls1tech.com/forums/generatio...1-lifters.html

Okay, now I am confused.
Old 06-08-2011, 10:25 AM
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Originally Posted by hardcore4sure
Wow, ok so 7.350 or 7.375 is what I need? I'm really puzzled why PatG would recommend this length? I even double checked with him after I ordered the cam from EPS and Geoff asked why I was going with 7.425 instead of 7.4?
Not sure why he'd recommend that length. Your measurements with the proper tool and method confirm this length! 7.375" would be the way I'd go!
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Old 06-08-2011, 04:17 PM
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Originally Posted by Darkman
Yeah you beat me to it.
Old 06-08-2011, 04:24 PM
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How would you all explain the OP's combo, where the person who spec'd the cam and has tested the cam on stock lifters recommends 7.425", yet with a simple swap to the LS7 lifters it CLEARLY needs 7.375"? This is not a new thing, we've been dealing with the LS7 lifters for several years!
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Old 06-21-2011, 11:00 AM
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Another question. I got my 7.375 pushrods in and installed them. I torqued to 22 then turned her over a few times by hand and this is how the valve tips looked since I colored in the tips with a sharpie. The intake looks centered but not the exhaust. Any thoughts or am I ok? Thanks

Old 06-21-2011, 12:12 PM
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Originally Posted by Matt@Texas-Speed
How would you all explain the OP's combo, where the person who spec'd the cam and has tested the cam on stock lifters recommends 7.425", yet with a simple swap to the LS7 lifters it CLEARLY needs 7.375"? This is not a new thing, we've been dealing with the LS7 lifters for several years!
I did not say you were wrong, I said I was confused. That confusion flows from that simple fact that two experienced, knowledgeable sources (Texas Speed and Thunder Racing) are saying two different things, at the same time, about the same lifter.

(Since I am running Morels I don't have a dog in this hunt.)
Old 06-21-2011, 03:28 PM
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ok nevermind on the sharpie question for the moment, I think I measured the wrong size pushrods.

so today once i got the new 7.375s in i wanted to make sure so i got a straw this time and put her all the way in and turned the crank till i felt it was at the highest spot and i believe this time its accurate as its going to be.

i measured at 9.75 turns aswell as 10 turns as before and now it feels even better to me at 9.5 turns which would make it 7.350 the better fit?

please take a look at the vids i took and lmk what you think is the best..thank you

http://www.youtube.com/watch?v=FINpWgt-8Oc
http://www.youtube.com/watch?v=P2UUudXVww8
http://www.youtube.com/watch?v=PTa1TPCF2bQ
http://www.youtube.com/watch?v=hzil_meT_gs
http://www.youtube.com/watch?v=jOVh9gtntnk
http://www.youtube.com/watch?v=PSvbEEjtA9c

Last edited by 408Maro; 06-21-2011 at 03:39 PM.
Old 06-21-2011, 04:05 PM
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Its hard to tell from the video but one observation, the 10 turns looks like you are forcing it a bit and in the process pushing down with some force on the pushrod/lifter, which will give a bit. Be very very gentle when you move the tip up and down so no force is transferred through the rocker to the pushrod (like you are lifting the tip with a feather).

Looks to me like either 9.5 or 9.75 is in the ball park.

One other note, if you need to alter the wipe by shimming or reducing the rocker height, this will also change the pushrod length. So if you plan to alter the wipe pattern at all do that first then measure.
Old 06-21-2011, 04:37 PM
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Thank you. Yes forgot to mention that the 10 is very hard like it looks. So think ill be ok with the 9.75 turn 3.75 pushrods? Or would you rather get some 7.350s in my situation? Thanks again. And don't want to shim or change anything besides get the correct size. Thanks again
Old 06-21-2011, 06:10 PM
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Personally I would install the 7.375".
Old 06-21-2011, 06:16 PM
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Cool just keep with what I got. Thank you


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