Jump to content

L83 (5.3) Cam options to retain AFM

Todd1982

By Todd1982
in Engines & Drivetrain

Recommended Posts

Todd1982 Enthusiast

Todd1982

Posted
Posted

Hello

 

What is available out there for 5.3 camshafts that retain the AFM?

 

Thanks 

Jglew82 Enthusiast

Jglew82

Posted
Posted

Give the guys at Brian Tooley or Texas Speed a call and let them know what you are looking for. All I've seen are cams designed for AFM deletes, but they can give you a better answer. 

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
7 minutes ago, pewterliftedz said:

None, the lifters cant take a bigger cam.

The lifter is the part that fails (occasionally) but it isn't the root cause of it's own failure. 

pewterliftedz Enthusiast

pewterliftedz

Posted
Posted
1 minute ago, Grumpy Bear said:

The lifter is the part that fails (occasionally) but it isn't the root cause of it's own failure. 

Huh?  The lifter collapses under load and thus fails.  Explain to me what the root cause is.

The fact is that the only reason to swap in a cam is for more power, AFM cams have really low lift and don't make power.

ksiesel Enthusiast

ksiesel

Posted
Posted
7 minutes ago, pewterliftedz said:

Huh?  The lifter collapses under load and thus fails.  Explain to me what the root cause is.

The fact is that the only reason to swap in a cam is for more power, AFM cams have really low lift and don't make power.

I believe the AFM lifter is designed to collapse - that's how it keeps the valves closed on that cylinder in V4 mode.

 

The problem is that when it's in V8 mode there is a ledge that the spring pin engages and this ledge gets mushroomed.  Once that happens, the lifter will collapse to go into V4 mode, but now the inner bore drags on the mushroomed ledge.  In this condition, the lifter can no longer extend so that valve will not open in V8 mode.  What's worse is that it also means there is now no preload on the valvetrain for that valve so you get a no follow condition on the cam.  This is the rattle that you hear and can easily progress to lifter bore and cam damage.

 

There is also a misconception that oil is fed to the AFM lifter in order to make it solid for V8 mode operation.  This is the opposite of what's true as the oil pressure being fed to the lifter actually retracts the spring pins and allows the lifter to collapse.

 

So, when someone says they have a "collapsed lifter", what it really means is that their AFM lifter has collapsed and will not extend on it's own like it should during every single combustion event of V4 mode.

pewterliftedz Enthusiast

pewterliftedz

Posted
Posted
46 minutes ago, ksiesel said:

I believe the AFM lifter is designed to collapse - that's how it keeps the valves closed on that cylinder in V4 mode.

 

The problem is that when it's in V8 mode there is a ledge that the spring pin engages and this ledge gets mushroomed.  Once that happens, the lifter will collapse to go into V4 mode, but now the inner bore drags on the mushroomed ledge.  In this condition, the lifter can no longer extend so that valve will not open in V8 mode.  What's worse is that it also means there is now no preload on the valvetrain for that valve so you get a no follow condition on the cam.  This is the rattle that you hear and can easily progress to lifter bore and cam damage.

 

There is also a misconception that oil is fed to the AFM lifter in order to make it solid for V8 mode operation.  This is the opposite of what's true as the oil pressure being fed to the lifter actually retracts the spring pins and allows the lifter to collapse.

 

So, when someone says they have a "collapsed lifter", what it really means is that their AFM lifter has collapsed and will not extend on it's own like it should during every single combustion event of V4 mode.

I understand that the lifter is designed to compress when AFM is activated, but it will not "reactivate", thus why people use the term collapsed.

300 Blackout Enthusiast

300 Blackout

Posted
Posted
45 minutes ago, pewterliftedz said:

I understand that the lifter is designed to compress when AFM is activated, but it will not "reactivate", thus why people use the term collapsed.

Melling did a video about the lifter problem. They evaluated numerous failed lifters and they suggested that the VLOM and it’s programming was the root cause of the collapsed lifters. 

 

Comp Cams is where I would look if I was going to keep AFM. I’m not sure what your goals are with the cam (power, speed, etc...), but if you’re not dead set on getting a cam, re-gearing your differential will give you the biggest bang for you buck. Depending on your tires and what gears, you will substantially increase how often you are driving in 4 cylinders and your gas mileage may actually improve. 

pewterliftedz Enthusiast

pewterliftedz

Posted
Posted
1 hour ago, 300 Blackout said:

Melling did a video about the lifter problem. They evaluated numerous failed lifters and they suggested that the VLOM and it’s programming was the root cause of the collapsed lifters. 

 

Comp Cams is where I would look if I was going to keep AFM. I’m not sure what your goals are with the cam (power, speed, etc...), but if you’re not dead set on getting a cam, re-gearing your differential will give you the biggest bang for you buck. Depending on your tires and what gears, you will substantially increase how often you are driving in 4 cylinders and your gas mileage may actually improve. 

Re-gearing is a instant seat of pants upgrade.  On my 07 5.3 I swapped from 3.73 to 4.56, and it was awesome.  I'm in the middle of collecting parts to gear swap my truck from 3.23 to 3.73 due to my 34" tires.

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
8 hours ago, pewterliftedz said:

Huh?  The lifter collapses under load and thus fails.  Explain to me what the root cause is.

The fact is that the only reason to swap in a cam is for more power, AFM cams have really low lift and don't make power.

300 Blackout / Melling Performance answered your first sentence.

 

Let's address the bold type above. 

 

The 5.3 on E-85 makes 1.2 hp/cubic inch and does it at 5600 rpm! Almost 1.3 lbs/ft per cube ! That is a BMEP of 193 psi at peak torque. That is the very ragged edge for E-85 fuel. In 1967 the 289 Ford in Shelby tune produced 305 hp but had to be spun 7,200 rpm to make it. It was peaky and required 100 octane fuel. The 5.3 is a race motor that is as meek as a kitten. A very effective camshaft.

 

My guess is you are not very old.  

 

HeySkippyDog Senior Enthusiast

HeySkippyDog

Posted
Posted
300 Blackout / Melling Performance answered your first sentence.
 
Let's address the bold type above. 
 
The 5.3 on E-85 makes 1.2 hp/cubic inch and does it at 5600 rpm! Almost 1.3 lbs/ft per cube ! That is a BMEP of 193 psi at peak torque. That is the very ragged edge for E-85 fuel. In 1967 the 289 Ford in Shelby tune produced 305 hp but had to be spun 7,200 rpm to make it. It was peaky and required 100 octane fuel. The 5.3 is a race motor that is as meek as a kitten. A very effective camshaft.
 
My guess is you are not very old.  
 
This reminds me of the "Why are Chevy trucks so slow?" thread.

They really aren't, for what they are in today's world.

But nobody will be satisfied until their factory built 1500 can match a Corvette. [emoji849]

Sent from my SAMSUNG-SM-J727A using Tapatalk

pewterliftedz Enthusiast

pewterliftedz

Posted
Posted
8 hours ago, Grumpy Bear said:

300 Blackout / Melling Performance answered your first sentence.

 

Let's address the bold type above. 

 

The 5.3 on E-85 makes 1.2 hp/cubic inch and does it at 5600 rpm! Almost 1.3 lbs/ft per cube ! That is a BMEP of 193 psi at peak torque. That is the very ragged edge for E-85 fuel. In 1967 the 289 Ford in Shelby tune produced 305 hp but had to be spun 7,200 rpm to make it. It was peaky and required 100 octane fuel. The 5.3 is a race motor that is as meek as a kitten. A very effective camshaft.

 

My guess is you are not very old.  

 

The AFM 5.3 leaves a lot to be desired compared to a aftermarket cam.  Have you ever driven one of these trucks with a cam, tune, or long tube headers?  These LT1 based engines can have huge gains with these mods, but you won’t get the huge gains with AFM lifters.  The average after market cam for these engines is 600ish lift, they do that because that’s how you make big boy power.   And no I’m not very old, but I do understand how to make power on the LS/LT power plants, and keeping AFM lifters isn’t how you do it

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • diyer2
      AFM Experience

      By diyer2 · Posted

      Hey guys, sorry for the confusison about this. This wasn't my experainnce, it was copied and pasted fom the net. 
    • KARNUT
      AFM Experience

      By KARNUT · Posted

      The problem with failure rates or increase failures are there’s people who don’t have a problem. What are you doing wrong they say. We had 4 5.7 GM diesel’s in the family when they came out. One was flawless. My uncle who happened to be the most abusive. Early rotary engines were known to use oil. I abused my first car so bad in six months I replaced the clutch, transmission and rear end. It didn’t use oil. My brother in law has a 2013 Tahoe and an older Yukon. The Yukon has 280K miles. The Tahoe around 175K. He runs them to about 300K. If his lifters fail before that time he would consider it a failure. My Hondas, I know people hate it when I mention them. Identical engines. One with cylinder deactivation one doesn’t have it. One shudders when the eco light goes on or off. Cylinder deactivation. But wait! According to the web. It can happen with lock up too. So now people in the know are changing the oil and transmission fluid more often. Then you read it could be a programing issue. So what do you do? There’s lots of money involved. I see three ways to deal with it. One only works if you don’t drive lots of miles. Lease, never get out of warranty. Or only buy older vehicles with a good track record. They all have bad runs. Usually when there’s a change. Even Toyota and Honda. 
    • Grumpy Bear
      AFM Experience

      By Grumpy Bear · Posted

      Question @diyer2 on this line if you please. Are you saying the shudder is the system turning on and off at the frequency of the shudder? Guess I'm asking if you are saying you have seen it do this with the bi-direction scan tool in graph mode? If so have you been able to discern the 'trigger'. Something is telling to cycle rapidly.    My truck just started doing this recently. 197K on the clock. My response has been M5 anything under 55 mph. I treat it like a lugging stick shift. Gear down and let it spin a bit. Engauge M5, then tow mode and then M6 lets the trans stay in 5th but the AFM is active. Smooth like Skippy.    My thought was that as a machine ages the friction gets lower and as the system is load based, the lower friction would allow it to turn on at ever lower rpm until it reaches the lugging point. And yes I am ignorant of any minimum rpm requirement for the system. If you know that would be useful information.    As you know I run a Scan-Gauge II which allows me to watch the On/Off of the signal to the VLOM. While in the shudder mode I'm not seeing is cycle at that frequency or at all for that matter outside the triggers @newdude posted a few years back. Now is it possible that the refresh rate isn't fast enough to catch it? Maybe. It is why I asked my first question about graphing and trigging parameter.     As we have observed from members here the failure point is all over the map miles wise as you note yourself in your opening post. That by itself begs a few questions like fellows that comment on these lifters failing even after the system has been disabled. Long after. 😬   https://www.enginelabs.com/news/tech-tips-replacing-ls-active-fuel-management-lifters-with-melling/   The Gen5 lifters operate the same as the LS versions. In fact they are the same lifter.    https://www.enginelabs.com/tech-stories/sorting-out-gen-v-lt-lifter-failure-with-a-simple-valvetrain-fix/        
    • SwitchBladeSierra
      14-18 Sierra 1500 Heated Steering Wheel Help

      By SwitchBladeSierra · Posted

      UPDATE 2: Steering wheel control backlights and control of the cluster can supposedly be achieved by adding a wire to pin 20 of the cluster and tapping it to pin 2 of the main clock spring harness. I'm going to give it a shot - will update  
    • newdude
      Seems to be Missing a lot of Updates

      By newdude · Posted

      GM Global A pickups 2019-2022 can do OTA programming for the radio.  GM VIP (GM Global B) can do OTAs for almost every module on board.  So a 2022.5 and newer pickup can do OTAs for recalls like the 2.7 fuel flow recall.  EVs get OTAs that improve one pedal driving, radio issues, HVAC issues, updated battery management software, etc.     So age of the vehicle/what GM electrical platform its on will alter what amount of updates can be pushed on OTAs.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...