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| | | Forums66 Topics128,035 Posts1,055,441 Members48,422 | | Most Online14,466 Apr 26th, 2026 | | AD Chevy Trucks Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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on the Internet for over 30 years! and not clogged down with Ads! Again, thanks! | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | Putting a 5.3 in my 51, 3100. The engine came out of a 2013, 2WD, Silverado and came with the 6L80E transmission.
I plan on installing an AFM (Active Fuel Management) delete kit, which requires a new cam, lifters and associated parts. I also plan on retaining the VVT (Variable Valve Timing) system. Anybody out there done this and what's the degree of difficulty with regard to re-installing the VVT?
Haven't ordered my kit yet and I'm not sure what technical instructions come with the kit. I'd like to get an idea if this project is within my skill set so any feedback would be appreciated.
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Mar 2010 Posts: 10,271 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,271 | What is the reason for AFM delete kit? New cam, lifters, etc sounds like a big expense and a lot of labor. Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | From what I can gather, a common problem with AFM is that the lifters that collapse to allow 4 cylinder operation, while the system is activated, start to make metal internally and eventually stick in the collapsed position. I want to eliminate that possibility by deleting the system before I get it installed in a completed truck.
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Aug 2012 Posts: 1,214 Shop Shark | | Shop Shark Joined: Aug 2012 Posts: 1,214 | Can't help you with instructions but I agree with your quest to delete the AFM. I've had several friends who've experienced collapsed lifters on their Burb's and the engines stayed in 4 cyl mode. One actually got his to clear by adding trans fluid to the oil but for how long it lasts and if it had long term damage is another story. He was going to replace the engine if it didn't work so he figured what did he have to loose....
Doing it while the engine is out makes it a whole lot easier but that depends upon your skill set. I just did a quick search for AFM Delete on the youtube and several hits came back. You might pursue a few to get a good idea on it's complexity. Perhaps someone here will happen along with experience also.
Good luck. Dave | | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | Dave,
I've looked at some of the YouTube, how to videos on the AFM delete and that seems pretty straight forward.
Getting the VVT back together properly is where I need to educate myself. Not finding any technical data so far.
With the wealth of experience on this site, someone has to have done this, maybe Coilover?
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Feb 2004 Posts: 29,749 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,749 | To the best of my limited understanding of the system, VVT is fairly simple mechanically, but it has a pretty sophisticated computer control system. The cam(s) start out advanced for low speed torque, and oil pressure and a helical 2-piece timing gear is used to retard the cam position for high speed horsepower and to control combustion chamber temperature to reduce the formation of oxides of nitrogen. That's why VVT engines usually don't have an EGR valve. The mechanical assembly of the VVT system should be pretty straightforward- - - -just follow the service manual procedures for engine assembly.
Cadillac tried cutting out cylinders with their V8-6-4 system back in the early 1980's by using a movable rocker arm pivot to disable intake valves. The system was pretty good at dropping cylinders out- - - - -and terrible at getting them back into operation. Those engines got replaced with conventional V8's under warranty almost immediately! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
| | | | | Joined: Sep 2011 Posts: 1,451 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 1,451 | I see no reason to replace cam & lifters, If AFM lifters aren't being unlatched & latched all the time they should not fail to latch which if how they usually fail. Seen many gagets that plug into the data connector to disable AFM.
BC 1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc 1949 GMC 250 project in waiting 1960 C60 pasture art Retired GM dealer tech. 1980 - 2022 | | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | BC,
That's a good point but I bought this engine and transmission out f a wrecked truck. I have not heard it run so I don't know if the issue of a collapsed lifter already exist. I'd hate to put it in my 51 and have a problem.
I am getting my engine/transmission harness trimmed and a tune in the computer that will make the engine/transmission electrical system a stand alone unit. They turn the AFM command off via the tune of the computer. To your point, if a lifter has not failed yet, I should be good to go.
Would it be an acceptable practice to pull all the AFM lifters and replace with new lifters of the same P/N and continue to use the original cam?
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Mar 2010 Posts: 10,271 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,271 | Here is how I look at selecting modern alternative engines in old vehicles. The engine needs to be a huge improvement over stock. It needs to pretty much fit in the vehicle without severe alterations. It needs to be proven to be ready to run. No mystery engines of unknown history for me. That is where big money comes into play. Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Sep 2011 Posts: 1,451 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 1,451 | D.B. Pull the rocker covers & rotate the engine, if a AFM lifter has failed (unlatched) it will have lots of slack between the rocker & valve stem. If you get the ECM calibrations to disable AFM & keep VVT I'd see no need to replace cam & lifters. If the lifters are always latched the aren't going to fail.
BC 1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc 1949 GMC 250 project in waiting 1960 C60 pasture art Retired GM dealer tech. 1980 - 2022 | | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | BC59,
Thank you very much, I'll follow your recommendation. I'll let you know what I find.
Thanks again!
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Jul 2019 Posts: 559 'Bolter | | 'Bolter Joined: Jul 2019 Posts: 559 | The dod stuff in those trucks is terrible. I have been working on these engines for a long time now and have had enough of them with issues with just the dod crap to say get rid of it. I usually recommend people buy 4.8’s for swaps because very few even had the dod/afm stuff. I currently have 2 LS powered vehicles (both swaps). Ive done multiple swaps and the only issues i ever see the others have were related to that. The solenoids will leak down sometimes and actually cause a 4 cyl mode when not requested and some will simply wear out the lifter bore from lack of oil and ive seen one spin in the tray and take out the cam and glitterbomb the motor. I just did a delete on one in a 72 c10 a month ago and the owner is nothing but smiles when asked how it runs. Its a pretty straightforward thing to do. No big surprises. We pieced his together with a front cover I already had and a used gear from another motor. He was putting a different cam in it anyways so it all made sense. | | | | | Joined: Sep 2015 Posts: 157 'Bolter | | 'Bolter Joined: Sep 2015 Posts: 157 | Barnfind49,
I did pull the rocker covers and rotated the engine thru while observing the pushrods and rockers. All the pushrods and rockers operated normally. I'm leaning toward leaving it as is with the AFM disabled and hope for the best. Hope I don't regret it.
Thanks for the feedback.
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
| | | | | Joined: Jul 2019 Posts: 559 'Bolter | | 'Bolter Joined: Jul 2019 Posts: 559 | Barnfind49,
I did pull the rocker covers and rotated the engine thru while observing the pushrods and rockers. All the pushrods and rockers operated normally. I'm leaning toward leaving it as is with the AFM disabled and hope for the best. Hope I don't regret it.
Thanks for the feedback. You wont know until it runs. But if its quiet and good then it should be fine. Even if it gives you problems later its still a easy fix even in the truck. These motors just come apart nice and easy and everything is reusable. Gaskets, bolts, pretty much everything. Normally if i have a LS engine apart the only thing i even replace is lifters and the o ring on the pickup. I put 200k mile old bearings right back in them without even thinking about it. I reuse every gasket unless it has paper head gaskets. Ive reused steel head gaskets multiple times no issues. My current engine in the gmc has 140k on it with stock plugs and wires and runs like a top and dosent leak a drop.
Last edited by Barnfind49; 08/20/2019 11:28 AM.
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