Like the title says.. I got a great deal on a supposedly blown up engine. It was misfiring on cylinder 1 and burning a LOT of engine oil to the point it destroyed the cats. It's a 5.3L engine from a 2007+ truck. It has the DOD & AFM with the engine oil solenoids on the underside of the valley pan. So, I got the engine basically for free. When I tore it down I find that the valve guide seal for the intake valve on cylinder #1 is GONE.. It's not damaged, it's physically missing. The entire engine is in perfect condition except cylinder #1 has a thick layer of carbon on the piston, the exhaust port is dripping in engine oil and the plug & combustion chamber for cylinder #1 are just coated in both burned, and unburned engine oil. All bearings are perfect including the cam bearings! I'm not sure how the missing valve guide seal came about but it appears it's the only problem. I sent the heads (243's) to the local machine shop and had them rebuilt. I had them check cyl. 1 valve guides specifically for any types of problems. They replaced both valve guides, and put in all new seals.

So, I'm building this engine for a 1969 GTO and need to know what all needs to be modified on the engine block to allow it to work as a GEN 3. I will be swapping the intake manifold over to a DBC and DO NOT NEED any of the AFM DOD stuff. Do I need to drill, tap, and install pipe plugs in the oil feed holes in the block valley? Or, can I just bolt the factory cover back on with the solenoids, and just not hook up the wires? Are there any other mods to the block that need to be done to permanently delete the AFM/DOD stuff internally????? I'm asking the BRAIN TRUST here at LS1 tech as I'm sure someone has done this before. The block cleaned up with a very mild hone and the factory pistons (flat tops) still have the black coating on the sides of them! This engine was very clean except the problem on cyl. 1.

 

Use an ls3 valley cover. It plugs everything for the AFM. You’ll have to tap the sides of the block for the gen3 knock sensors.

Theres a couple other things too of you are using a gen 3 harness

 

Big Hammer-THANK YOU for the excellent information. I will start looking for an LS3 valley pan now on-line.

Yes, I'm using a Gen 3 harness. I think I will have to modify the harness due to the cam position sensor being on the FRONT of the engine now. I can tap the engine block for the knock sensors. Are there any other mods that relate to the oil pump, or oil pump feed holes in the block????

 

Will something like this work;

 

No. that unit blocks the oil pressure sensor hole off. I’d go GM if I were you. Are you changing the reluctor wheel on the crank, or are you using the converter box?

 

That's an excellent find

Regarding valve seals, the black ones GM uses are pretty terrible. Sometimes you can slid them on and off with your fingers. The BLUE Viton seals hold up way better.

 

One of those will be needed if you are using an older Gen 3 PCM with the Gen IV motor. The late 5.3 will have the 58x reluctor wheel on the crank, and will not work with a Gen 3 PCM looking for 24x.

Also the crank position sensor needs to be correct. If you run the 24x reluctor, you will need the 24x version of the sensor.

 

If your motor is apart you could drill and tap the oil towers (3/8-16), using thread sealer on set screws and never worry about internal oil leaks or damaging oil pressure loss. Then, use a PCV Valley cover from GM, made for gen4, it’s drilled and threaded for oil pressure switch and it’s a good system to vent your crankcase.12570471 gm