I am currently building a nitrous 5.3 with 706 heads milled .042, weisco junkyard dog pistons, and a ljms stage 4 ls3 cam. I had the heads ported for nitrous and removed the bump in the intake runner and am ready to do a valve job on them. Should I go with a 2.0 intake valve or stick with the stock 1.89?

 

I would prefer 2.02", but 2.0" would be a nice upgrade too. Bumping up to a 1.60" exhaust valve would also help in a nitrous combo.

 

Thanks for the reply KCS. I should have mentioned I dont want to spend a ton of money on these heads. Can you do 2.02 valves using the existing seats? Also would it have any negative effects when running the car n/a?

 

Yes you can since the stock intake seats are 2.02" in diameter, but a 2.02" is the largest I would run. Not sure about the exhaust seats, but the 1.60" will work just fine as well. I had that combo on my old 241 heads. The only drawback is a little more money for the valves versus a stock valve and a little more valve weight. Both are negligible for the increased curtain area and potential port size with the larger valve.

 

I just had 2.0 valves put in 706 heads, no issues. Did upgrade to the GM perf corvette springs.