4.8 Question

[71Sleeper]

So, I just picked up a 2007 4.8 with 799 heads which is very clean without the harness and ECM. The question that I have, how can I tell if it is equipped with AFM or not. I have been researching but some sites say the 4.8came with AFM and some say no. I don't know what type of vehicle it came from. The guy I bought it from sold it because he was told it had AFM and it wasn't worth using. But for what I paid for it the heads alone were worth the buy.

[67 chevelle]

You can take the intake off , and the valley pan ,, turn it over , if its flat ,no afm , if its got grooved oil passages in it , it has afm ,, easier way is checking by the vin number

[99turbogmc]

It's fine, trust me... I run a 4.8 with stock heads, intake and short block in my turbo single cab. Cam only, large frame t6 s475 turbo threw a th400 and slicks on 15 psi and I make over 640hp and beet the hell out of it..... And it has 220k miles on it...

[99turbogmc]

So is he saying vvt is better? Smh I have 2 friends with lifter problems in there truck as we speak. One has already had a lifter replaced under warranty. Now warranty is going out and he's screwed.

[67 chevelle]

vvt good ,, afm bad ,, afm lifters are more likely to fail,, some of the ls engines that had neither had lifter failure , usealy the front lifter on the drivers side , dont know why , buts it is what it is , ls engines are one of the best designed engines ever

[fwayne]

AFM engines have a solenoid in the valley pan. You can delete this and change out the lifters for the 4 cylinders that use AFM. AFM is simple, it uses oil pressure to enable/disable the lifter. by replacing the lifters with normal ones, the feature is disabled and you wont have the dreaded failure of those lifters.

BTW its a roller lifter cam, you can replace them with good used lifters no worry about them like you used to on flat tappets.

I'm actually considering the same engine because they cost half as much as a 5.3, and with a cam swap and tune they make almost the same power.

kits are available to do this such as this from summit https://www.youtube.com/watch?v=AaHYII4ZmSc

[71Sleeper]

Good news today. The casting number on the block was listed as a 4.8 hence the reason the PO sold it to me. Well today I wanted to confirm if it had AFM or not. To my surprise when I removed the head I found cross type pistons staring back at me, 5.3 my lucky day. Now I will just replace the cam and lifters and be on my way. But first I need to track down a 07 or 08 wiring harness, E38 ECM, pedal and tac box.

[GM-power]

Were the pistons flat tops or dished?