So if you had a set of MDS heads, would you be able to tear them down and install regular rockers on them? For those of you who know, they have those funky rocker arm setups on them. Just curious if you tore them down to do springs/rockers if you could do different rockers and maybe use them on non-mds motors or what not. Or if you would just be able to port/polish them and have to leave the stock setup alone. I have never seen the pre 06 non-mds heads torn apart, so I don't know if they are the same or not, but I would assume that they are as far as bolt setup and such is concerned.

I have never checked one against the other, but they appear to be the same.

but it sounds like a good questiong for art

i dont think there is ANY difference in the heads, just those 4 MDS hydraulic intake lifters. Never heard of there being anything different with the rocker arms.

There is no differance in the heads. The only differance is the 4 MDS lifters. And if you cam it those lifters will get louder!

Anyone have a link like on how stuff works or something that shows the live action cross-section of how our hemis work? I was thinking there was one and one on an mds motor, but I can't remember where it was.

http://www.youtube.com/watch?v=W4JDi0K8htY

Sweet! That's a good start. Pretty quick vid though. Hard to really understand how the MDS works too. Will have to do my research...

These are the Hemi's four plastic hydraulic valve lifter cage assemblies. As you can see, they're a piece of cake to install. What you can't see is any difference between the conventional lifters and the special 2-piece MDS cylinder-deactivating lifters.

The pistons have a graphite-based coating for scuff resistance. The connecting rods are made of powdered metal and have cracked bearing caps for an exact fit. The compression ratio for the modern 5.7-liter Hemi V8 is 9.6:1, compared with 10.25:1 for the original 426 Hemi.

MDS MAKES FOUR FROM EIGHT
The whole point of this exercise was primarily to explain and demonstrate the 2005 Hemi's new Multiple Displacement System (MDS) in an enlightening manner more fun than your average Powerpoint presentation. We got to see the four solenoid valves--mounted directly to the engine block down in the valley of the V8--that disable cylinders 4 and 6 (the two inners on one bank) and cylinders 1 and 7 (the two outers on the other bank) under light engine loads. This switch-over is totally transparent to the driver, because the V4 operation utilizes even 180° firing intervals. The only thing the driver feels is joy when he calculates how much less fuel he's using on a long drive. Chrysler says the Hemi in the 300C sedan is rated for 25 mpg on the highway.

Here's how MDS works: There are four special 2-piece roller lifters for the cylinders that get disabled. The two pieces are concentric--there's an inner portion surrounded by an outer sleeve. The two parts are locked together by two spring-loaded pins when the engine is in 8-cylinder mode and all the pushrods are operating their valves normally. Under light loads, however, the engine management computer signals each solenoid valve to open and apply high oil pressure to its respective exhaust- and intake-valve lifters. This action forces the two pins in each disabling lifter to unlock the two concentric parts. (To help minimize oil contamination, there’s a magnet at the bottom of each solenoid unit to collect ferris debris.)

Now, the outer sleeve continues to follow the camshaft lobe, but the inner portion of the lifter just floats. This results in no pushrod movement, so the valve springs keep the valves closed. Spark and fuel for the respective MDS cylinders are shut off, and now the engine is in 4-cylinder mode.

1. The rocker shaft bosses contain lubrication holes because the MDS solenoids take up so much real estate down in the valley that the hydraulic lifters couldn’t be lubricated through a conventional oil gallery. In the 5.7-liter Hemi, the oil flow circuit first feeds the main crankshaft bearings and the camshaft bearings, then runs up to the rocker shafts/rocker arms, which in turn feed through the pushrods back down to the integral valve lash adjusters in the roller lifters. This configuration, by the way, allows the standard Hemi and the MDS Hemi to both be built on the same assembly line.