3900 Monte Carlo head build

[bearbear3_4]

I've been drag racing my Monte Carlo the past few months and have become addicted to it. My best time is 15.2 with only basic mods. In the next month I'm going to be porting the heads and adding a 100 shot of nitrous and doing a complete tune. For those who have built up the 3900 whats a good cam and spring setup to go with?

I do plan on down the road to go turbo but I'm looking to get into the 14's this season and doing the turbo build over the winter.

[ericjon262]

I don't think anyone currently makes a cam for it, I know Mast motorsports is big in the VVT LSx motors, they might have some words of wisdom on lobes and making power on VVT.

[Fieroghini]

I installed a 3400 cam with the help of WOT. It's pretty big, maybe too big, and requires the PAC springs which are a little loud. Talk to Sappy and see if he can help you out with the spacers to install the cam. The quench is also on the large side so I ordered thinner head gaskets which require new pushrods again, so decide if you want to do that mod and do them all at the same time to save a little money. I also have headers, northstar throttle body and 3.73 gears in my 4t65e. I ran a 13.35 at 103.8mph in a Fiero. The power is still lower than what people are claiming with the 3500 non vvt so you may want to consider that route.

[bearbear3_4]

Thanks for the replies. I think I want to hold off on a cam right now till I'm to the point of a upgrading the bottom end. Right now I'm just looking to do the heads with new rollers with springs and a port maybe try to find a larger TB that will work with the TBW.

I see a number of threads of people who are working on replacing the rollers but it looks like no one has posted that they finished with any gains.

[SappySE107]

I suggest leaving the heads alone as far as porting goes. The VVT aspect of an LS isn't the same as the 3900. The cam should be designed for the engine, not the technology itself. i am no sure if there are any spacers left for the cam. I don't believe more will be made but I am not certain.

[bearbear3_4]

Thanks, I won't do a port but how about a polish at least?

What do the cam spacers do? I've never heard of these.

[pocket-rocket]

The cam bearing journals are different sized between standard pushrod cams and the VVT (or at least the 3.9) engines. The spacers fill in this gap so you can run a standard (non-VVT) cam in a VVT engine and do away with VVT and run an older style ECM.

[bearbear3_4]

Oh okay, I do want to keep the VVT so the cam is staying. Does LS rockers and springs fit the LZ9 head?

[SappySE107]

You can remove any casting flash, and polish up the exhaust ports.

[ericjon262]

Take a look at the following thread, lots of good details there.

http://60degreev6.com/forum/showthread.php/41450-3.9L-LZ9-engine-internal-upgrade-amp-performance

[ericjon262]

I suggest leaving the heads alone as far as porting goes. The VVT aspect of an LS isn't the same as the 3900. The cam should be designed for the engine, not the technology itself. i am no sure if there are any spacers left for the cam. I don't believe more will be made but I am not certain.

maybe not exact same, but they are both only advancing and retarding the entire cam.