Ls2 408 stroker
11 Second Club
Joined: Jan 2003
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OP, how old are your coils? LS coils begin to deteriorate with age and can't spark adequately at high cylinder pressures over high 6k rpms and it won't show up as a misfire or anything. You will just be down on power and not think the coils are faulty. You need to swap on a NEW set of oem delco coils and re dyno it before opening up the engine looking for other issues. The stronger pushrods are a good idea, do those for sure. And check all your ignition wires for ohms resistance. If any are high, replace.
Also, what size are your headers? That combo needs 1 7/8 with 3.5" collectors minimum to make good power. If I were buying new I'd go 2" primary.
Also, what size are your headers? That combo needs 1 7/8 with 3.5" collectors minimum to make good power. If I were buying new I'd go 2" primary.
Last edited by Launch; Sep 8, 2019 at 06:13 AM.
Thread Starter
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OP, how old are your coils? LS coils begin to deteriorate with age and can't spark adequately at high cylinder pressures over high 6k rpms and it won't show up as a misfire or anything. You will just be down on power and not think the coils are faulty. You need to swap on a NEW set of oem delco coils and re dyno it before opening up the engine looking for other issues. The stronger pushrods are a good idea, do those for sure. And check all your ignition wires for ohms resistance. If any are high, replace.
Also, what size are your headers? That combo needs 1 7/8 with 3.5" collectors minimum to make good power. If I were buying new I'd go 2" primary.
Also, what size are your headers? That combo needs 1 7/8 with 3.5" collectors minimum to make good power. If I were buying new I'd go 2" primary.
Ignition wires are brand new.
Headers are 17/8 with dual 3 inch collectors.
9 Second Club
Joined: Feb 2004
Posts: 818
Likes: 215
From: VA
Wouldnt that side load if contact is made stress the rocker cup or pull the push rod out of the center of the lifter?
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Thought to update everyone.
First of all I spoke with Manton, and told them the issue I have been having and they are also certain it is the pushrods.
A trend 5/16 with an .80 wall will certainly not handle 500lb of open spring pressure, the heavier rockers and head valves plus high rpm capability.
Not surprised power is rolling over at 6000rpm.
This is the only explanation that is making sense to me.
Engine was only making 340rwkw when spring pressures were increased. It's an improvement from 325rwkw but power is still falling off after 6000rpm.
As others have said, the Manton pushrod is around 150% stiffer compared to the one that I have so it will be interesting to see how it turns out once installed.
If this still doesn't fix it I will need to go back to the standard rocker ratio and then I will most likely need different length pushrods again....
However I am confident the issue is the pushrods but we will see what happens.
Thanks everyone for your help and suggestions.
First of all I spoke with Manton, and told them the issue I have been having and they are also certain it is the pushrods.
A trend 5/16 with an .80 wall will certainly not handle 500lb of open spring pressure, the heavier rockers and head valves plus high rpm capability.
Not surprised power is rolling over at 6000rpm.
This is the only explanation that is making sense to me.
Engine was only making 340rwkw when spring pressures were increased. It's an improvement from 325rwkw but power is still falling off after 6000rpm.
As others have said, the Manton pushrod is around 150% stiffer compared to the one that I have so it will be interesting to see how it turns out once installed.
If this still doesn't fix it I will need to go back to the standard rocker ratio and then I will most likely need different length pushrods again....
However I am confident the issue is the pushrods but we will see what happens.
Thanks everyone for your help and suggestions.
So no, I don't think the contact would do that, but I haven't spintron tested to see what would happen. Though remember, there's a couple of hundred pounds of spring pressure keeping it all together.
Ideally, you don't want any side load on the pushrod. But if it were to kiss from any instability, it shouldn't hurt anything. One of the benefits of a melonite hardened pushrod.
On The Tree
Joined: Jun 2019
Posts: 184
Likes: 66
From: HTown, Texas
Thought to update everyone.
First of all I spoke with Manton, and told them the issue I have been having and they are also certain it is the pushrods.
A trend 5/16 with an .80 wall will certainly not handle 500lb of open spring pressure, the heavier rockers and head valves plus high rpm capability.
Not surprised power is rolling over at 6000rpm.
This is the only explanation that is making sense to me.
Engine was only making 340rwkw when spring pressures were increased. It's an improvement from 325rwkw but power is still falling off after 6000rpm.
As others have said, the Manton pushrod is around 150% stiffer compared to the one that I have so it will be interesting to see how it turns out once installed.
If this still doesn't fix it I will need to go back to the standard rocker ratio and then I will most likely need different length pushrods again....
However I am confident the issue is the pushrods but we will see what happens.
Thanks everyone for your help and suggestions.
First of all I spoke with Manton, and told them the issue I have been having and they are also certain it is the pushrods.
A trend 5/16 with an .80 wall will certainly not handle 500lb of open spring pressure, the heavier rockers and head valves plus high rpm capability.
Not surprised power is rolling over at 6000rpm.
This is the only explanation that is making sense to me.
Engine was only making 340rwkw when spring pressures were increased. It's an improvement from 325rwkw but power is still falling off after 6000rpm.
As others have said, the Manton pushrod is around 150% stiffer compared to the one that I have so it will be interesting to see how it turns out once installed.
If this still doesn't fix it I will need to go back to the standard rocker ratio and then I will most likely need different length pushrods again....
However I am confident the issue is the pushrods but we will see what happens.
Thanks everyone for your help and suggestions.
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Thread Starter
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Joined: Sep 2010
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I need 7.800 length.
3/8 will not fit.
I have already ordered 11/32 .120 wall dual tapered pushrods from Manton.
I wish I could fit 3/8.
If heads ever come off I will do the clearancing for the 3/8 for sure.
Tensile strength is misleading. It is load divided by cross section area.
A 1/2 inch bar and a 2 inch bar both have a tensile strength of 100,000 psi. The half inch bar max load is about 19,600 lbs. the 2 inch bar max load is 314,000 lbs.
That is why you need to look at load and stiffness, not tensile strength.
A 1/2 inch bar and a 2 inch bar both have a tensile strength of 100,000 psi. The half inch bar max load is about 19,600 lbs. the 2 inch bar max load is 314,000 lbs.
That is why you need to look at load and stiffness, not tensile strength.
Thread Starter
TECH Addict
Joined: Sep 2010
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Tensile strength is misleading. It is load divided by cross section area.
A 1/2 inch bar and a 2 inch bar both have a tensile strength of 100,000 psi. The half inch bar max load is about 19,600 lbs. the 2 inch bar max load is 314,000 lbs.
That is why you need to look at load and stiffness, not tensile strength.
A 1/2 inch bar and a 2 inch bar both have a tensile strength of 100,000 psi. The half inch bar max load is about 19,600 lbs. the 2 inch bar max load is 314,000 lbs.
That is why you need to look at load and stiffness, not tensile strength.
I noticed you have the series 5 pushrods. Do you know the figures for these on top of your head?
I was thinking of getting this series but LGM said they are overkill for my application and the series 3 will be more than enough.
Damn, they are expensive pushrods though but they are one of the best from what I have read.
Do you think the series 3 will be quite capable?
Thread Starter
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Thread Starter
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Found this article too which may be of interest to some:
http://www.sbintl.com/tech_library/a...erformance.pdf
http://www.sbintl.com/tech_library/a...erformance.pdf
Thread Starter
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Does anyone know the stiffness difference between an 11/32 .120 wall pushrod in the series 300 and series 500 from Manton?
As many of you know I have the series 300 ordered so just curious on the difference.
As many of you know I have the series 300 ordered so just curious on the difference.