olysan

Hey guys long time no post!

I'm thinking about upgrading the vortec heads on my 406 this winter. Minimum change will be new 2.02/1.6 valves. I'm looking for some opinions on the following:

Will this upgrade alone get me any hp? My exhaust is stock merc thru-hull with silent choice.

Should I think about porting the heads while I have them off, if so what will that get me?

Where is the best place to get my valve train parts? I'm on a budget.



Regards
Mike

blown1500

Just my 2-cents worth,
You may want to re-think your valve choice. I have read and been told by people who should know, that a 2.02 intake valve in these heads is not the way to go unless you have a good pocket port at least and some chamber work to unshroud the valve. The usually recommended size is usually 2.00". Without pocket port and port match at least, the gains could be negative. Good valves with 2.00" intake and 1.6" exhaust and some pocket work and port match will give noticable gains. Just valve size increase is a waste. Also, have someone upgrade the valve springs-this requires machining the spring pockets. If I can help or if you need parts, call me at 704-574-4020. I have access to great parts at GGREAT prices.

bobl

I've had very good results going to 2.02/1.60 Valves in Vortec heads, along with a good bowl blend and unshrouding the valves a little. For valve springs I run the Crane 10309 spring/retainer set. They are made to drop right in those heads and are great for most mild hydraulic or hydraulic roller cams. You are restricted to about .470 lift unless you cut the guides a little bit on those heads. I did a boat recently and used the Crane 104224 cam and the head work. With no other changes the boat picked up 5 MPH on GPS.

Bob

olysan

I'm running the comp cams XM262 extreme marine cam now. Ultimately I'd like to go to a roller cam, so I'm trying to make modifications with that in mind. That means I'll need to change the valve springs since the stock springs are only good for something like .480 lift.

bobl - Are you saying that the Crane 10309 spring/retainer set is only good for .470, or are you refering to the stock limitations?

Thanks guys.

bobl

The springs are good to almost .600 lift. The problem is the retainer hits the valve guide at about .480 lift. You just need to get the guide cut down a little for whatever lift you decide to run if it's over .480".

Bob