Read this:

02 to 05 4200 have a plastic cam cover.
06 to 09 have an aluminum cam cover.



The blocks use a dry cast iron sleeve in them - they are replaceable. 2004 up have better sleeves.

2006 up rods are stronger and have oil squirters in them to cool the pistons.

Cranks

All cranks are cast. They will support 1100 hp.

2002-2005 cranks are fully counter weighted. 7 timing notches
2005 SERVICE cranks are cross drilled - rare part. Also the best crank. 7 timing notches
2006 - 2007 reduced counterweights, cross drilled 7 timing notches
2008 - end of production, reduced counterweights cross drilled 58 timing notches

Personal experience - the 06 up cranks are hard on rod bearings due to dynamic loading especially if your running performance parts.

Heads

The 2002 - 2005 heads are inferior in terms of flow.
The 06 up heads are better.

The key to making a 4200 go is head porting especially on the exhaust side. Starting with a 06 head is better.

Quick engine ident.

2002 to 2005 engine use plastic cam cover.
2006 up use an aluminum cam cover.

If you change from early to late head the following parts need to change:

head
cam cover
ignition coils
exhaust manifold
VVT actuator

The cam timing is slightly different between the early and late engines.

In stock form the engine will support upto 15 psi boost with a good tune.

Marc, glad to see you are still flying the flag for the 4200.

Anyhow, I was parts searching. From what I can tell the 02-09 engines all used the same VVT solenoid. The difference comes in the cam sensor and reluctor. I found a Standard Motor products PC804 sensor for the 08-09 and PC 403 for the 02-07.

Anyhow, please correct me, if I am missing something.

I've been watching Craigslist and Ebay for several years. I've seen quite a number of the 06 and newer with spun rod bearings. I have an 08 in the shed that has had the rod bearings beat out of it. GM changed the oil filter specifications for these motors in 06 also, They stopped using filters with anti-backflow valves. I wonder if they were trying to get a little more oil volume. Anyhow, I've seen quite a number of 02-05 models with 200-300,000 miles on them and still kicking. I personally have an 04 with 225,000 and it still runs as strong as ever.

With all that said, I'm thinking the 02-05 equipped with the later head is the best combination to be had. I know you lose the oil squirters, but it seems you enhance the lower end durability.

Chris.

I think your correct, the VVT solenoid is common.

So when swapping heads you can retain the cams from your original head right? And by cam cover, what are you referring to?

the head, cam cover (valve cover), vvt, coils, exhaust mannifold all need to be the same year as the head.

When changing to the the later head the water temp sensor wiring needs to change to passenger side rear of the head. GM moved the sensor.

the 06 up intake cam has a little bit more duration than the early cams

exhaust cams are identical

you choice on what cams to run.

Gotcha, thanks for the clarification. I've got my eye on a few later year 2006 heads and all the accompanying same-year parts.

I'm considering getting the '06 up head for my '05 block.

It seems smart to pick up the extra HP before dropping the engine into the build.

I'd made a split header from the old flange kit. Is the bolt pattern different on the '06 and up head?

And what is the expected difference in HP? given bigger injectors and a header? Round numbers OK

in stock form 15 HP. with head porting - 25-30

Is there a different bolt pattern On the ‘06 up exhaust flange?

bolt pattern - same - but the ports are different. Need to use the same year head/exh. manifold.

Thanks.

I have the flanges I purchased a few years back from the man in Northern California.. He made flywheels at the time.

I'll have to check the port alignment.

Can the aluminum valve cover be used on the earlier plastic valve cover heads?

It appears possible.

Looks like we're on our own again with 4200 builds!

No to using plastic v/c on 06-09 head.

Doug, was thinking aluminum V/C on '05 head.

Backwards compatible?

nope the bump for the VVT is different.