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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: clinebarger] #5181698 08/08/19 06:30 AM
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kstanf150 Offline
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Originally Posted by clinebarger
Originally Posted by nthach
Originally Posted by clinebarger

That's really the achilles heel of the 2V OHV arrangement.....Valve Control! About the only pattern failure I've seen with the 6.2L Ford is broken valve springs, And it's a 2V OHC arrangement. Ford is having trouble just controlling large/heavy valves & a Rocker Arm.....Now the 7.3L will have even larger valves & much more weight to control (Lifter, Pushrod, & Rocker Arm).


If valve float is an inherent weakness in an OHV engine, how is GM and Mopar mitigating it in the LSx and the Hemi(especially the Hellcat/Demon variants with forced induction)? I'm guessing stiffer, variable-coil valve springs with a beefier, bolted on rocker arm assembly, roller lifters and VVT?


Not so much valve float.....Breaking valve springs is a phenomenon that is ALMOST exclusive to OHV engines. Though I recently seen a broken spring on a 3.6L Pentastar. And of coarse the many Ford 6.2L OHC engines I've seen with broken springs being an outlier.

LSx & Hemi's probably break springs more than any modern engine. The lowly 4.8L being the worst of the lot......Have to rev them to make power & it will only take so much duty cycle.

Beehive/Ovalet springs certainly help, Smaller diameter spring retainers reduce mass.
Hollow stem valves also help reduce mass, All the high performance engine your thinking of use hollow stem valves. Not a technology generally found on truck engines.

Roller lifters add mass & VVT doesn't change the cam profile just valve/cam timing. Not to be confused Variable Lift/Profile technology (Honda Vtec).


Broken springs may not be a wide spread topic/known issue.......Engines are replaced over it a lot of times. Where a simple vacuum gauge will diagnose it.


What do suppose is the reason for broken springs on the Ford 6.2 (design flaw or supplier quality) or user neglect of good maintenance of oil changes ?

Re: Fords new 7.3 liter engine is a pushrod engine? [Re: kstanf150] #5181826 08/08/19 09:34 AM
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A_Harman Offline
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Originally Posted by kstanf150
Originally Posted by clinebarger
Originally Posted by nthach
Originally Posted by clinebarger

That's really the achilles heel of the 2V OHV arrangement.....Valve Control! About the only pattern failure I've seen with the 6.2L Ford is broken valve springs, And it's a 2V OHC arrangement. Ford is having trouble just controlling large/heavy valves & a Rocker Arm.....Now the 7.3L will have even larger valves & much more weight to control (Lifter, Pushrod, & Rocker Arm).


If valve float is an inherent weakness in an OHV engine, how is GM and Mopar mitigating it in the LSx and the Hemi(especially the Hellcat/Demon variants with forced induction)? I'm guessing stiffer, variable-coil valve springs with a beefier, bolted on rocker arm assembly, roller lifters and VVT?


Not so much valve float.....Breaking valve springs is a phenomenon that is ALMOST exclusive to OHV engines. Though I recently seen a broken spring on a 3.6L Pentastar. And of coarse the many Ford 6.2L OHC engines I've seen with broken springs being an outlier.

LSx & Hemi's probably break springs more than any modern engine. The lowly 4.8L being the worst of the lot......Have to rev them to make power & it will only take so much duty cycle.

Beehive/Ovalet springs certainly help, Smaller diameter spring retainers reduce mass.
Hollow stem valves also help reduce mass, All the high performance engine your thinking of use hollow stem valves. Not a technology generally found on truck engines.

Roller lifters add mass & VVT doesn't change the cam profile just valve/cam timing. Not to be confused Variable Lift/Profile technology (Honda Vtec).


Broken springs may not be a wide spread topic/known issue.......Engines are replaced over it a lot of times. Where a simple vacuum gauge will diagnose it.


What do suppose is the reason for broken springs on the Ford 6.2 (design flaw or supplier quality) or user neglect of good maintenance of oil changes ?


I think the 6.2 suffers from excessive mass at the valve. Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: double vanos] #5181899 08/08/19 11:01 AM
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Any idea if spring failure is more on the intake side or exhaust ? Or just a combination of both

Last edited by kstanf150; 08/08/19 11:05 AM.
Re: Fords new 7.3 liter engine is a pushrod engine? [Re: A_Harman] #5182086 08/08/19 01:59 PM
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CR94 Offline
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Originally Posted by A_Harman
... Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.
Multiplied by the square of the rocker ratio.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: CR94] #5182205 08/08/19 04:12 PM
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Originally Posted by CR94
Originally Posted by A_Harman
... Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.
Multiplied by the square of the rocker ratio.


Oops. You're right.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: kstanf150] #5182421 08/08/19 08:37 PM
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clinebarger Offline
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Originally Posted by kstanf150
Any idea if spring failure is more on the intake side or exhaust ? Or just a combination of both


I've seen both.....The good news is, It doesn't normally drop a valve or otherwise damage the engine.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: clinebarger] #5182449 08/08/19 09:19 PM
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kstanf150 Offline
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Originally Posted by clinebarger
Originally Posted by kstanf150
Any idea if spring failure is more on the intake side or exhaust ? Or just a combination of both


I've seen both.....The good news is, It doesn't normally drop a valve or otherwise damage the engine.



Thanks good news since I own a 6.2 Ford
But again why do you think the springs are failing ??

Re: Fords new 7.3 liter engine is a pushrod engine? [Re: double vanos] #5182476 08/08/19 09:53 PM
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clinebarger Offline
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The extra mass of the Hydraulic Lifter being placed right over the valve like I & A_Harman already stated. I'm not aware of any other engine using this design .

Ford could have ran mechanical lash adjusters like Honda does. The 3.5L Ecoboost & 3.7L V6's use solid lash buckets.....It's not like they're married to hydraulic lash adjusters. Though Lash Buckets are more of a Mazda design.
Using a similar to Honda design would allow quick valve lash adjustment every 100,000 miles.....Where adjusting the lash on a Ecoboost/Duratech V6 is roughly a 15 hour operation if adjustments need to be made.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: clinebarger] #5182490 08/08/19 10:27 PM
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kstanf150 Offline
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Originally Posted by clinebarger
The extra mass of the Hydraulic Lifter being placed right over the valve like I & A_Harman already stated. I'm not aware of any other engine using this design .

Ford could have ran mechanical lash adjusters like Honda does. The 3.5L Ecoboost & 3.7L V6's use solid lash buckets.....It's not like they're married to hydraulic lash adjusters. Though Lash Buckets are more of a Mazda design.
Using a similar to Honda design would allow quick valve lash adjustment every 100,000 miles.....Where adjusting the lash on a Ecoboost/Duratech V6 is roughly a 15 hour operation if adjustments need to be made.


How much difference is there between the old 427 SOHC arrangement and the 6.2L as far as cam and rocker arm design ???

Re: Fords new 7.3 liter engine is a pushrod engine? [Re: double vanos] #5182504 08/08/19 11:04 PM
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clinebarger Offline
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Pretty similar.....Though the 427 Cammer used Mechanical Lash Adjusters!

Here's a 2015 6.2L valvetrian pic......Motor is toast, Didn't feel like lifting a pic off the web.....

[Linked Image]


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: double vanos] #5182561 08/09/19 05:34 AM
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Originally Posted by A_Harman



I think the 6.2 suffers from excessive mass at the valve. Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.


I like how Mazda did it. They seem to have figured out turbo/DI, "fill for life" transmission fluid, etc. as well.
[Linked Image]
[Linked Image]

On their Skyactive engines, Mazda uses a class 3 lever (similar to BMW's 14,000rpm S1000RR design), and a low-friction roller cam follower. But the pièce de résistance is the hydraulic lash adjuster (HLA) at the fulcrum.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: Ws6] #5182562 08/09/19 05:37 AM
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Originally Posted by Ws6
Originally Posted by A_Harman



I think the 6.2 suffers from excessive mass at the valve. Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.


I like how Mazda did it. They seem to have figured out turbo/DI, "fill for life" transmission fluid, etc. as well.
[Linked Image]
[Linked Image]

On their Skyactive engines, Mazda uses a class 3 lever (similar to BMW's 14,000rpm S1000RR design), and a low-friction roller cam follower. But the pièce de résistance is the hydraulic lash adjuster (HLA) at the fulcrum.



FYI, that's the exact same way Ford did it on the Modular.


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Re: Fords new 7.3 liter engine is a pushrod engine? [Re: dave1251] #5182565 08/09/19 05:45 AM
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Originally Posted by dave1251
Originally Posted by JHZR2
It seems like a stoichiometrically tuned DI would be a good case study for economics and power. The effect on cooling/combustion temperatures, etc would seem to have a benefit, especially under high duty cycles.

Honestly I’m surprised they didn’t push the hybrid DI/port to ensure cleanliness with the benefits of DI.

Interesting to read all the comments on timing chains. Wonder how many folks have actually lined up marks and measured wear in the chain and sprocket.



The wear I've seen from experience is nearly the same on non DI and DI engines further demonstration maintenance practices are key. Still it does not justify over maintenance which most members do.


Point was that chains do wear, and the chain and/or other elements are replacement items.

DI is a different part of my discussion, in that chains aside, the thermal benefits of DI would notionally line up well with efficient tuning.

Re: Fords new 7.3 liter engine is a pushrod engine? [Re: clinebarger] #5182570 08/09/19 05:49 AM
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Originally Posted by clinebarger
Pretty similar.....Though the 427 Cammer used Mechanical Lash Adjusters!

Here's a 2015 6.2L valvetrian pic......Motor is toast, Didn't feel like lifting a pic off the web.....

[Linked Image]



Looks like A lot of neglect on the owners part played into the demise of that motor. Probably never had an oil change in its life 😳🤔🤔🤨🤨

Re: Fords new 7.3 liter engine is a pushrod engine? [Re: OVERKILL] #5182577 08/09/19 05:59 AM
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Originally Posted by OVERKILL
Originally Posted by Ws6
Originally Posted by A_Harman



I think the 6.2 suffers from excessive mass at the valve. Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.


I like how Mazda did it. They seem to have figured out turbo/DI, "fill for life" transmission fluid, etc. as well.
[Linked Image]
[Linked Image]

On their Skyactive engines, Mazda uses a class 3 lever (similar to BMW's 14,000rpm S1000RR design), and a low-friction roller cam follower. But the pièce de résistance is the hydraulic lash adjuster (HLA) at the fulcrum.



FYI, that's the exact same way Ford did it on the Modular.


Same as the Pentastar v6 as well. It’s a great system imo.


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