Are shorter pushrods required with LS7 lifters?
05-04-2007, 04:07 AM
#21
TECH Senior Member
Originally Posted by BAD2000TA
I totally agree. I had a problem with bad ticking when my motor warmed up. I have MTI's Stealth II cam (XE-R lobes) and .020 decked LS6 heads. The push-rods were Trick Flow 7.40 and I am using the GM MLS gasket. I ordered the push-rod checker and I verified the length on four different lobes. I came-up with 7.30 at zero lash. Adding .080 for preload, I need 7.38" push-rods. I ended-up shimming the rocker shaft .020 and the ticking was dramatically reduced.
brian
brian
On stock rocker assemblies only p-rod length alters preload.
05-04-2007, 04:09 AM
#22
TECH Senior Member
FYI,
I've been trying to get more accurate info on the LS7 lifters. This is the answer from Matt at SDPC:
But we all know that stock OEM length and aftermarket length vary by as much as .020 !!! Hmmmm
I wish someone that measured or can measure would chime in.
I've been trying to get more accurate info on the LS7 lifters. This is the answer from Matt at SDPC:
Re: LS7 lifter specs
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Unfortunately we haven't had any of the original LS1 lifters here in quite a while, so I can't get any measurements from one. From what I was told by a GM tech, they are close enough that they should still be able to use a stock pushrod (assuming the cam/heads/etc are stock).
Matt
Quote:
Originally Posted by PREDATOR-Z
Hi Matt,
Perhaps you could help us. Are the dimentions of the LS7 lifter different from OEM LS1/LS6 lifters.
Like from roller to cup, plunger distance till bottoming etc...
And could it be possible that swapping them in might require a shorter pushrod.
Some poeple in the Gen III internal are experiencing ticking after motor warmed up. Quiet on cold. Could aftermarket 7.400 be too long once motor is warm?
Any info would help
Thanks
Mark
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800-456-0211 ext 358
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Unfortunately we haven't had any of the original LS1 lifters here in quite a while, so I can't get any measurements from one. From what I was told by a GM tech, they are close enough that they should still be able to use a stock pushrod (assuming the cam/heads/etc are stock).
Matt
Quote:
Originally Posted by PREDATOR-Z
Hi Matt,
Perhaps you could help us. Are the dimentions of the LS7 lifter different from OEM LS1/LS6 lifters.
Like from roller to cup, plunger distance till bottoming etc...
And could it be possible that swapping them in might require a shorter pushrod.
Some poeple in the Gen III internal are experiencing ticking after motor warmed up. Quiet on cold. Could aftermarket 7.400 be too long once motor is warm?
Any info would help
Thanks
Mark
__________________
Matt Craft
E-mail Me
Click To Visit Scoggin Dickey's Website
800-456-0211 ext 358
I wish someone that measured or can measure would chime in.
05-04-2007, 07:51 AM
#23
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Funny, some people want 500rwhp and it run quiet as a mouse. When you start using large cams and making your factory geometry do strange things that would even surprise Newton, it's gonna make some noise. Just get a louder exhaust and you won't hear it 
Seriously, the best method is to check the length and buy the right pushrod to start with. But you will not have mechanical trouble if you use 7.40" with LS7 lifters, ok maybe if your running like .700+ lift, but besides that, you're cool.
Seriously, the best method is to check the length and buy the right pushrod to start with. But you will not have mechanical trouble if you use 7.40" with LS7 lifters, ok maybe if your running like .700+ lift, but besides that, you're cool.
05-09-2007, 04:43 PM
#24
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i'm getting 5.3l heads milled to 61cc & using a .040" head gasket so I was going to use 7.425" pushrods. I do want to replace my lifters with the ls7 lifters so I hope these pushrods are still fine.
05-09-2007, 07:01 PM
#26
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Originally Posted by davered00ss
Turns out I did need 7.35 pushrods. Just ordered them from Texas Speed. 
05-03-2008, 01:02 AM
#28
i just did an install today, i bought both sets of pushrods (7.4's and 7.35's) first i brought #1 up to TDC on the compression stroke (both valves closed) and installed the 7.4's man they was tight. i torqued them to spec, and there was no leway on the rocker arms. usually they move a little when you grab them and give them a shake from side to side, but they were TIGHT. so i installed the shorter ones, and repeted the same process it felt much better and wasent as tight.
BTW, i have an MS4 with TSP PRC STG 2.5 5.3's milled to 58cc's with stock GM MLS gaskets.
BTW, i have an MS4 with TSP PRC STG 2.5 5.3's milled to 58cc's with stock GM MLS gaskets.
