Pushrod length driving me crazy!
Safety Car
Joined: Jul 2005
Posts: 3,572
Likes: 9
From: Jackson Tn
St. Jude Donor '06-'07-'08-'09
Does that cam use Comp Cam's XER lobes? Just tuned a 2010 Camaro that had a 227/243 113 .614/.624 LSR Comp Cam, Kooks headers/exhaust and a 102 Fast intake. There was no valve train noise at all. Also there was no low speed buck/surge at all. Quietest cam I've heard on a LS motor.
Now after talking to Comp Cams about the LSL lobes used in their LSR cams, I'm going to swap my G5X3 114 cam for the 227/235/ 113 .614/.621 LSR cam.
The tech said I probably won't loose much if any top end power over the G5X3 cam, and will gain low load/low RPM drive-ability. And will be quiet because the LSL lobes seat the valves slower.
Russ Kemp
Now after talking to Comp Cams about the LSL lobes used in their LSR cams, I'm going to swap my G5X3 114 cam for the 227/235/ 113 .614/.621 LSR cam.
The tech said I probably won't loose much if any top end power over the G5X3 cam, and will gain low load/low RPM drive-ability. And will be quiet because the LSL lobes seat the valves slower.
Russ Kemp
Burning Brakes
Joined: Jul 2006
Posts: 968
Likes: 12
From: Regina Sask
I think there was some discussion that his lobes were his own design. But I was very impressed with the LSR cam in the 2010 Camaro.
What is your combo & which cam did you use?
How is your low throttle/load @50 mph in 4th like?
Russ Kemp
What is your combo & which cam did you use?
How is your low throttle/load @50 mph in 4th like?
Russ Kemp
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
The key to measuring is to ensure you are at zero lash. If you aren't sure, you can verify with feeler gauges as you measure.
Safety Car
Joined: Jul 2005
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From: Jackson Tn
St. Jude Donor '06-'07-'08-'09
I think it's @ 230/230 with a .600 lift at 112
Last edited by printmanjackson; Apr 27, 2012 at 04:25 PM.
Instructor
Joined: Oct 2010
Posts: 132
Likes: 1
From: johnstown pa
i'm probably missing something here but isn't this backwards? how would you achive more bolt turns with a longer pushrod?
"For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter..."
"For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter..."
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
Think of an extreme case as an illustration. You have a pushrod that requires lets say one turn to reach 22 lb-ft of torque on the bolt. The bolt tightening is from the point where the rocker is loose within the rocker stand until the rocker bottoms in the rocker stand and then to preload the bolt. Now increase the pushrod by 1/2". The rocker will sit much farther from the rocker stand and will require more turns to get it to bottom. As you turn the bolt the pushrod is depressing the lifter or developing preload. So as the pushrod length increase, so does the preload and vise versa requiring more turns on the bolt.
Drifting
Joined: Jun 2010
Posts: 1,349
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From: US
Think of an extreme case as an illustration. You have a pushrod that requires lets say one turn to reach 22 lb-ft of torque on the bolt. The bolt tightening is from the point where the rocker is loose within the rocker stand until the rocker bottoms in the rocker stand and then to preload the bolt. Now increase the pushrod by 1/2". The rocker will sit much farther from the rocker stand and will require more turns to get it to bottom. As you turn the bolt the pushrod is depressing the lifter or developing preload. So as the pushrod length increase, so does the preload and vise versa requiring more turns on the bolt.
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Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
you said stock heads.....228R is not a massive cam. i see you have pulled valve covers. did you find anything unusal? check for cracks, metal shavings, loose rockers, needle bearings etc. Can you post the sound? Man i know you dont have many miles on the setup but you might have a lifter going bad.
Safety Car
Joined: Jan 2012
Posts: 3,956
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From: Da U.P.
My old 5.0HO Ford is being the same way, got all the shims and longer pushrods to get preload within spec (.020-.060) and it's loud as hell with the stock HO cam (210/210 @ .050"). What I've come to wonder is if the lifters lived their lives at one preload for so many years, and you go putting in a new cam and whatnot ending up with preloads slightly different than before across the board, if the lifter doesn't like this? Seems unlikely in theory, but then again so do a lot of things.
Instructor
Joined: Oct 2010
Posts: 132
Likes: 1
From: johnstown pa
Think of an extreme case as an illustration. You have a pushrod that requires lets say one turn to reach 22 lb-ft of torque on the bolt. The bolt tightening is from the point where the rocker is loose within the rocker stand until the rocker bottoms in the rocker stand and then to preload the bolt. Now increase the pushrod by 1/2". The rocker will sit much farther from the rocker stand and will require more turns to get it to bottom. As you turn the bolt the pushrod is depressing the lifter or developing preload. So as the pushrod length increase, so does the preload and vise versa requiring more turns on the bolt.
