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Curious what length pushrods everyone is running with cam swaps? My heads were milled .025 and its taking rocker bolts past zero lash anywhere from just shy of 1 turn to 1.25 turns to 22/ft-lbs. 7.375" is the current length I have. Just want to make sure it doesn't make noise at 8k RPM. j/k
 

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Factory length 7.400. I have been kicking the idea around of running longer pushrods though.
 

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Discussion Starter #3
Factory length 7.400. I have been kicking the idea around of running longer pushrods though.
Do you have milled heads?
 

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Counting turns to 22lb ft works, better method is measure the length required using Amazon.com: COMP Cams 7702-1 Hi-Tech Pushrod Length Checker 6.800" to 7.800" Length: Automotive . Once you have the correct length and the target preload on the lifter, you can order the correct size pushrods. I found every length different (few 001s) and that pushrods were also different length when labeled to be the same. Depending on the lifter preload range, you may get by with one size. In my case, with johnson 2110 (less preload than OEM) and BTR pushrods, I was able to match the rods to the position
 

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7.375" is likely the correct length for you, but it also depends on the cam and lifters you're using.

Lifters - Some lifters require less preload than GM LS7 lifters. For instance, Johnson 2110 lifters are only 0.035" +/- 0.010", and for aluminum block, they recommend being on the + side of 0.035".
Cam - As cam lift increases past a point, you have to shrink the base circle of the cam, therefore you need a longer pushrod.

So, measure 3-4 times, and send it.
 

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Buy the length checker IMO. You prob think, "I'll never use it more than once"

I thought the same thing with my f-body cams... three swaps later 😑

PM sent

-J
 

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Discussion Starter #8
7.375" is likely the correct length for you, but it also depends on the cam and lifters you're using.

Lifters - Some lifters require less preload than GM LS7 lifters. For instance, Johnson 2110 lifters are only 0.035" +/- 0.010", and for aluminum block, they recommend being on the + side of 0.035".
Cam - As cam lift increases past a point, you have to shrink the base circle of the cam, therefore you need a longer pushrod.

So, measure 3-4 times, and send it.
Its a Pat G spec'd cam from TX Speed with LS7 lifters. They both thought 7.375 but I wanted to make sure. The whole checking process seems subjective to me but again its my 1st time. If you do the bolt torque method past zero lash, I've read that its anywhere from 3/4 turn to 1 3/4 turn. Some people seem to measure by the length it takes to get zero lash with only hand tightening the bolt then adding lifter preset. Everyone's hand tightening can be up to 1/2 turn different though. Maybe I roll with what I have since its close on both test. If there is noise then I adjust size. Thoughts?
 

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Its a Pat G spec'd cam from TX Speed with LS7 lifters. They both thought 7.375 but I wanted to make sure. The whole checking process seems subjective to me but again its my 1st time. If you do the bolt torque method past zero lash, I've read that its anywhere from 3/4 turn to 1 3/4 turn. Some people seem to measure by the length it takes to get zero lash with only hand tightening the bolt then adding lifter preset. Everyone's hand tightening can be up to 1/2 turn different though. Maybe I roll with what I have since its close on both test. If there is noise then I adjust size. Thoughts?
Pick up a pushrod length checker and be sure. Consider all you are doing, why cut corners now?
 
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From what I remember, hand tight kind of translates to, make sure the bolt is on the rocker and the rocker body no longer has up and down movement on the pedestal (not the same as rocking motion). So while hand tight is different for anyone, I seem to recall I thought of it more as "not loose" vs "hand tight". It's been a long long time, someone correct me if I'm wrong.

-J
 

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Its a Pat G spec'd cam from TX Speed with LS7 lifters. They both thought 7.375 but I wanted to make sure. The whole checking process seems subjective to me but again its my 1st time. If you do the bolt torque method past zero lash, I've read that its anywhere from 3/4 turn to 1 3/4 turn. Some people seem to measure by the length it takes to get zero lash with only hand tightening the bolt then adding lifter preset. Everyone's hand tightening can be up to 1/2 turn different though. Maybe I roll with what I have since its close on both test. If there is noise then I adjust size. Thoughts?
Yeah, it's probably right. Just depends on the specific spec of the cam, and if TX Speed cams are ground with smaller base circles. You could find the base circle size and compare to stock.
 

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Discussion Starter #12
Pick up a pushrod length checker and be sure. Consider all you are doing, why cut corners now?
I'm going to get one for sure, just hope my hand tight is dead on. 🤦‍♂️
 

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I used the comp cam checker and its looking like I need 7.4 instead. Thanks for everyone's input. I'm glad I double checked.
 

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Stock LS pushrod length is 7.385”. To get adequate preload, especially with a new cam, 7.400” is the new standard.I ran 7.400” just to reduce with the stock cam it get more preload
 

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Discussion Starter #15
Stock LS pushrod length is 7.385”. To get adequate preload, especially with a new cam, 7.400” is the new standard.I ran 7.400” just to reduce with the stock cam it get more preload
Gotcha, that's what I was reading. I just thought mine would need to be shorter since my heads were milled...guess not. ;)
 

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Your preload of 1 to 1.25 is where you want to be. I see you upgraded the oil pump. Which one did you get? Did you add a brace for the oil pump pickup? They are really important to keep the pickup square in the pump and extend the O ring life.
 

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Discussion Starter #17
Your preload of 1 to 1.25 is where you want to be. I see you upgraded the oil pump. Which one did you get? Did you add a brace for the oil pump pickup? They are really important to keep the pickup square in the pump and extend the O ring life.
I went with the Melling high volume oil pump and the improved racing brace for the pickup tube. The brace helped with lining up the original bolt as well. I applied German torque to both, gutentight/ftlbs.
 

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Good you used the best stuff. So it was the 10355 pump?
What is your hot idle oil pressure?
 

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Discussion Starter #19
Good you used the best stuff. So it was the 10355 pump?
What is your hot idle oil pressure?
I'm still a couple weeks away from starting it. There was a mix up with the wrong underdrive pulley being sent. Mighty mouse catch can and cold case radiator hoses on backorder. I just ordered new summit ignition coils and PatG tune as well. New motor mounts came today, going to install those and headers this weekend. I can't wait, going from just a CAI and can tune to all this fun stuff. Converter, gears and suspension will be next mods after I run this motor for a bit.
 

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Ahh. It’s just warm enough here I’ll be taking my engine and suspension apart too. When the heads are off will see if I can swing LS3 intake valves too.
 
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