Setup:
406 sbc chevy
062 casting vortec heads with screw in studs, guideplates,
500+lift springs. 64cc 1.94/1.50 valves
Hardened pushrods
Comp cams extreme energy .477/.480 lift and .268/.280 duration(advertised)
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hedman long tubes-dual 3 inch exhaust dumps before rear axle
.30cc dish keith black pistons
edelbrock rpm air gap intake
stock crank
mallory ignition
edelbrock 750 carb
th350 tranny
3.73 4th gen posi rearend
2200-2500 stall
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1.6 rocker question:

What kind of gains would i see from the 1.6 rockers over the 1.5's? Also is there anything else i would need to do other than elongate the pushrod holes in the heads? Would i need longer pushrods or anything? Also is there a special headgasket needed with the vortec heads?(needs to have steam holes for the 400)

Converter Question:

Would i see any gains from adding a 3000 stall? I currently have a 2200-2500 B&M holeshot converter.....

 

Regardless of the peak lift, the valves will stay open farther longer; so you'll pick up some flow. However, it won't be much.

If you haven't had the guides milled down, I would strongly recommend sticking with 1.5s.

If you have the springs that are supposed to go with that XE268, they would be 981s; they are good to .500" lift. To get past that lift, you'd need larger than stock diameter springs, which would require machine work to the spring pockets.

All in all, I'd say it's too much maze with too little cheese at the end.

I think you could pick up some launch with a higher stall converter, assuming the tires wouldn't go up in smoke.

 

They are aftermarket springs that came with the heads not sure what brand.... machine shop says they are good to high 500 lift, and yes the valve guides have been machined down and the springs are already in the heads so all machine work is already done other than having to make the pushrod holes bigger.... if that needs to be done? For the 100 dollars is it worth it for the 1.6s cause all the other work is already done