cam question - 1.6 rockers on teh LT1 intake side

[aaronkl84corvett]

Anyone try this?
i'd have to believe so - -

Getting ready to pull the non=OE cam out of my 69Z28 - and i'm tempted to run the LT1 with 1.6 on the intake and 1.5 on the exhaust.

curious on thoughts

[BCreekDave]

You’ll get a bit more torque due to the tighter LSA on the LT-1 cam at the expense of high RPM horsepower. The 1.6 rockers on the intakes will add nothing IMHO. Some can run the 69Z’ on premium unleaded due to the late exhaust closing bleeding off compression. The LT-1 cam closes the exhaust earlier so as to raise the dynamic compression and most likely mandating some amount of race gas to prevent detonation

[aaronkl84corvett]

You’ll get a bit more torque due to the tighter LSA on the LT-1 cam at the expense of high RPM horsepower. The 1.6 rockers on the intakes will add nothing IMHO. Some can run the 69Z’ on premium unleaded due to the late exhaust closing bleeding off compression. The LT-1 cam closes the exhaust earlier so as to raise the dynamic compression and most likely mandating some amount of race gas to prevent detonation

the LT-1 has a wider (116) LSA actually and the shorter intake duration both contribute to dynamic compression issues

But Im asking specifically about the difference running the 1.6 on the intake vs 1.5 all things being equal.

[BCreekDave]

Correct you are! I meant to say tighter on the 69Z cam, not the LT-1 cam. I still think you won't see any difference due to the rocker ratio. I've tried them on a couple different engines and haven't seen any noticeable difference, although not with this exact cam swap.
Maybe someone has done this exact swap.

[Lynn]

I have a set of 1.6 rockers I bought to run with a 30 30 cam. Never have installed them. I do have something close to an LT-1 spec engine in my Z right now (350, 11:1, LT-1 camshaft, 472 intake, recurved 480 dist. and 69 Z carb).

Didn't even think about running the 1.6 rockers on the LT-1 cam, so I have nothing but theoretical input on this. I seriously doubt you will feel any real difference. Unless you run it on a dyno with back to back runs, any perceived improvement is just as likely a placebo effect as it is real world results. Just my 2 cents.

[BCreekDave]

If anything I would be concerned about overloading an already marginally lubricated flat tappet cam. The 1.6 rocker is also effectively loading the cam face that much more. Most likely would not cause a problem but if you lost a lobe you would always wonder

[Hotrodpaul]

The 1.6 ratio rockers on the intake side will add flow area under the curve and horsepower, how much depends on your heads, valve job, etc. Just make sure the springs can handle the extra lift and I would break the cam in with the 1.5 rockers, and add the 1.6 ratio after the break in just to be safe. I would say the rockers would be worth 10-15 Hp.

Paul