Alright I know people say the 306 cam is old but I got great results with it. Anyhow I was thinking about changing from my 1.6rr to 1.7rr. I should get some horsepower out of this right?

Also I believe the lift on the exhaust side would be around .612, so I will need to upgrade my springs. Any valve spring recommendations for this 306 cam with 1.7rr with that much lift?

I always spun this cam to 6800rpms with the 1.6rr. Would there be any concern spinning it still this high with 1.7rr as long as I have the correct valve springs?

If there is not a valve spring recommendation for that lift, would it be a bad idea for 1.7rr on just the intake valve springs. Since the lift on those is still below .600. Also I could still use my 10308 valve springs with anything below .600 lift.

Also I believe someone said if I got 1.7rr I might need piston valve reliefs. I know my ross racing pistons I have in my engine now already have them. Did he mean I would need them to be deeper or did he just probably think I still have the stock LT1 pistons and do those not have valve reliefs?

 

PTV depends on the reliefs in the piston. Honestly you probably have a ton with that cam. I have a lot more duration than you, 105lsa and 104 icl and i didn't even touch the clay. Take a spring off, measure actual coil bind and installed height. Crane advertises 1.080 coil bind, depending on where you have them in at you could run .612 no problem. Those springs have plenty of rate for what you're trying to do.

 

I made that comment, I said that because you are running heads with 2.055 intake valves. But you have the relief valves so you will be fine, even with the rockers. Just make sure you get valve springs that can handle the lift