I have a 406 that has been pretty completely built out of the GM Performance Parts product line with exception of the cam, just the top of the line everything. This motor went 5.8x in the eigth in a 2600# car on a 200 shot.

My question lies in the heads. They are GM Bowtie Phase 2 iron heads. They have the blue aluminum rockers, HUGE double valve springs, and some of the fattest pushrods I've seen in a smallblock. They dont appear to have been ported anywhere.

I'm wondering if these heads are fully up to the task of handling all this power. And if there is alot more power to be found.

Thanks for any help guys.

-Justin

 

Nothing is wrong with the heads....Just get them ported. There flow numbers stock are nothing great. But with a little work they will make good power. With not much metal removed i usually get 280 cfm around .500-550

 

There is huge power in those heads. Like the previous poster said you need to port them completely, but not excessively. You do not need new heads.