Push rod help
Thread Starter
Pro
Joined: Jun 2007
Posts: 713
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From: Saratoga Springs Ut
Push rod help
Okay, I know this has been beat to death on here, but here's what's going on with mine.
I had a friend/customer of mine install TEA stage 1 heads along with a Texas speed 224r cam with .581 lift and 114 LSA. Thing runs great but needs a tune needless to say.
I had a lot of valve train noise after the install with 7.400 rods, so I did some checking with the 1 1/4 turns form 0 lash method, and came up needing a 7.350.
Well, it's still noisey. So I got serious about it, and got a push rod checker and rechecked it by turning out the checker and rechecking it until I got to 0 lash and came up with 8 1/2 turns to get to 0 lash.
So here's what I came up with....
6.800 + 8.5 truns(0.425) = 7.225 for 0 lash + .100 preload = 7.325 rod correct?
So with a 7.350 rod I'm still to long by 0.025.
Oh, and I also checked the wipe pattern, and it looks damm near perfect to me..
Just looking for some confirmation on what I'm doing is correct, and a 7.325 rod seems really short to me, and would 0.025 make that much difference in the way it would sound?
I had a friend/customer of mine install TEA stage 1 heads along with a Texas speed 224r cam with .581 lift and 114 LSA. Thing runs great but needs a tune needless to say.
I had a lot of valve train noise after the install with 7.400 rods, so I did some checking with the 1 1/4 turns form 0 lash method, and came up needing a 7.350.
Well, it's still noisey. So I got serious about it, and got a push rod checker and rechecked it by turning out the checker and rechecking it until I got to 0 lash and came up with 8 1/2 turns to get to 0 lash.
So here's what I came up with....
6.800 + 8.5 truns(0.425) = 7.225 for 0 lash + .100 preload = 7.325 rod correct?
So with a 7.350 rod I'm still to long by 0.025.
Oh, and I also checked the wipe pattern, and it looks damm near perfect to me..
Just looking for some confirmation on what I'm doing is correct, and a 7.325 rod seems really short to me, and would 0.025 make that much difference in the way it would sound?
Last edited by TheDEfan; Sep 18, 2011 at 06:14 PM.
Thread Starter
Pro
Joined: Jun 2007
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From: Saratoga Springs Ut
Corrected values, I think
Last edited by TheDEfan; Sep 18, 2011 at 06:16 PM.
Burning Brakes
Joined: Oct 2004
Posts: 985
Likes: 23
From: Florence SC
Maybe I misunderstand
If you have valve train noise with 7.400 push rods how can it be expected to decrease with shorter push rods? And I need to ask another question, as I'm fixing to add the YT's myself. I have a adustable pushrod for lenth checking, why not just adjust the lash to zero, measure the lenth and add .040. I'm asking here, would that method be acceptable? After verifying wipe pattern of course.
Thread Starter
Pro
Joined: Jun 2007
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From: Saratoga Springs Ut
If you have valve train noise with 7.400 push rods how can it be expected to decrease with shorter push rods? And I need to ask another question, as I'm fixing to add the YT's myself. I have a adustable pushrod for lenth checking, why not just adjust the lash to zero, measure the lenth and add .040. I'm asking here, would that method be acceptable? After verifying wipe pattern of course.
I think you need more than 0.040 preload. From what I've read you need at least .080
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Also, if the heads have been worked the valves may be deeper and require a shorter pushrod. You might want to check a couple of cylinders just to verify consistency.
Last edited by vettenuts; Sep 19, 2011 at 05:11 AM.
Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
As far as added noise, make sure your valve springs are not going into coil bind. With heads of unknown background it might not be the right spring for the cam.
This chart shows the dynamic range for all the different GM lifters over the years. The last lifter on the list, 17122490 is the LS7 lifter. Normal preload should be 2.09mm or .082".
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Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
If you have the very early lifter this would be correct. With a performance cam I would normally change out the lifters to the newer 17122490 lifter. Note the part number is different if you buy a set of 16. The newer lifters are less likely to pump up at higher rpms compared to the early units.
Thread Starter
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Joined: Jun 2007
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From: Saratoga Springs Ut
If you have the very early lifter this would be correct. With a performance cam I would normally change out the lifters to the newer 17122490 lifter. Note the part number is different if you buy a set of 16. The newer lifters are less likely to pump up at higher rpms compared to the early units.
Drifting
Joined: Jul 2005
Posts: 1,484
Likes: 27
From: Torrance Calif
You might consider using MORELs.
I used RHOADS (noisy) and couldn't get rid of the noise till I installed the Morels.
However, they seem to work the best at a very light preload (0.005").
Any more then that and I would trip a P300 code.
I used RHOADS (noisy) and couldn't get rid of the noise till I installed the Morels.
However, they seem to work the best at a very light preload (0.005").
Any more then that and I would trip a P300 code.
Team Owner
Joined: Mar 1999
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From: At the beach in little Rhody
At 0.005" I would wonder whether any preload remains from cold to hot when things expand.
Drifting
Joined: Jul 2005
Posts: 1,484
Likes: 27
From: Torrance Calif
That's interesting. My Morel's were noisy at startup at 0.030" and absolutely quiet at 0.053" preload. Someone here recently found similar results with his preload and is ordering special pushrods to achieve this preload.
At 0.005" I would wonder whether any preload remains from cold to hot when things expand.
At 0.005" I would wonder whether any preload remains from cold to hot when things expand.
I had the PCM tuner look at this and he opened up the tolerance on the mis fire table.
I am running a Comp Cams #1500 adjustable rocker system.
With the RHOADS lifters, it never was quiet at any preload except almost all the way.
It didn't trip the P300 code as often with the RHOADS.
The MORELs are noisy at startup, but once the oil thins out, they are bitchin.
Burning Brakes
Joined: Oct 2004
Posts: 985
Likes: 23
From: Florence SC
push rod length
This thread has got me all intercoursed up. From the 1998 LS1 needing .118 preload, but a 99 LS1 needs .080, all the way to wondering whether .005 preload remains after engine warm up. I personally was thinking the preload would increase with temp. but after thinking about the aluminum block and head expansion rate, now I'm wondering too. Surely sombody here has adustable rockers that has (or will) set preload cold then checked it hot just to see where the valve train is at during operating conditions. My old SB 400 with pontiac heads decreased the lash by ~.015 from cold to hot settings. 
Thread Starter
Pro
Joined: Jun 2007
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From: Saratoga Springs Ut
Wow I just want my engine to not sound like a Singer. I just might throw the 7.325 rods in it and see what happens before I go pulling the heads off.
Last edited by TheDEfan; Sep 19, 2011 at 10:50 PM.
Melting Slicks
Joined: Dec 2003
Posts: 3,315
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From: Near Jacksonville Fl.
It's really hard to belive you need a .100 shorter push rod with a cam ground on a smaller base circle.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
It's really hard to belive you need a .100 shorter push rod with a cam ground on a smaller base circle.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
Melting Slicks
Joined: Jun 2005
Posts: 2,396
Likes: 52
From: Sicamous BC
Exactly! I kept re reading this thread wondering what I'm missing. I just changed out my cam, the pushrods I ordered are .075 longer than stock.
Maybe the OP is not on the Base Circle, I know with my LSK lobes I could not use TDC, I had the cam 180* from dot to dot then things measured out correctly.
Maybe the OP is not on the Base Circle, I know with my LSK lobes I could not use TDC, I had the cam 180* from dot to dot then things measured out correctly.
It's really hard to belive you need a .100 shorter push rod with a cam ground on a smaller base circle.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
Thread Starter
Pro
Joined: Jun 2007
Posts: 713
Likes: 9
From: Saratoga Springs Ut
It's really hard to belive you need a .100 shorter push rod with a cam ground on a smaller base circle.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
When I did mine with used patriot heads my PR length increased to 7.425 to get .050 preload with LS7 lifters.
I'd recheck your measurments making sure your on the base of the cam.
So I can't assume that the base is smaller. And the heads have been milled, by how much I'm not sure. I'm on the base. I checked 4 rods/valves and came out the same on each one. I assumed I was to short as well at first and installed 7.425 and the thing would idle but died as soon as I let out the clutch. I was hanging the valves open at the point.
Last edited by TheDEfan; Sep 20, 2011 at 10:37 PM.