Hello- I have a 406 with stock vortec heads. Does anyone have any experience installing the larger valves 2.02x1.60. Would the money spent on installing larger valves be worth what you will get in return as far as performance. or should I scrap the vortec and go to an aftermarket head. any info would be great Thanks!!  

If this is one of the original Vortec casting numbers, I'd say sell 'em on E-bay and move on. They're rather strapped to feed a 406. If you haven't modified them for more lift, better stem seals, larger dia springs, steel pushrod guides already, there probably isn't any advantage to pouring more money into them as opposed to replacing them with a set of aftermarket heads or the updated Vortecs.

Bogie

Bogie  

if your dead set on using these heads and it's a street engine then i would skip spending money on larger valves.i would spend the money on converting to screw in studs and comp cams behive springs/retainers.they allow for a decent sized cam with out any spring seat or valve guide mods.i've only read this but it has been written that bigger valves can mess up the great port velocity these heads are known for on the intake side.if you are going to get a new cam also,then more duration on the exhaust side can help,that's their weak point.i have the h.o. 350 crate engine with these heads and i put some lt1 springs with the flat inner spring removed and 1.6 crower stainless roller rockers,even though those are no-no's i shift at 6 grand and run 13.80's around 100mph with a 71 camaro th350 2500 converter and 3:73 posi rear and a very very stiff suspension.  

id leave the valves alone.the new bowtie vortecs have a larger port volume,yet have a 2.00 intake valve and they flowbetter than the original vortecs.dont expect to have any power above 5 grand with these heads on a 406,but expect lots of tire fryin torque.