boot85

iTrader: (2)

I am thinking of doing the ls swap into one of my novas and weighing things out. I was reading an old super chevy article were they carbed an LQ4 and ran the .525 lift Hot cam and then ran the showroom special .570 lift cam. They talked about having to valve notch the stock pistons.

http://www.superchevy.com/technical/.../photo_04.html

My question, how high of lift can you go without having to notch the stock pistons? I wanting keep cost down so I would like to use the stock pistons.

boot85

iTrader: (2)

I see that some have used .600+ lifts with stock pistons and have not said anything about clearancing the pistons. I will call the manufacturer but for now I'm curious what a reasonable limit is, what duration and LSA will work.

tennerv8

iTrader: (7)

I have a .573/.571 lift cam in my 6.0. I am also running L92 heads, which brings the intake valve a little closer to things with having a 2.160 intake valve. I have a good amount of room for ptv clearance. PTV clearance has more to do with all of the valve events rather than just lift.

boot85

iTrader: (2)

Ok, good to know. thank you

Doug G

.624 lift I/E and dished pistons (LQ4) still needed both fly-cut about .100 or so for .90 I and .100 E clearance (I have to look again to be 100%)

Prorac1

iTrader: (4)

Its not the lift that is the big determining factor in P to V clearance. Its intake centerline. When its lower, (I.E. 106 or 108) your P to V will be closer than a cam thats 112-114. Hope this helps, Eric L

speedtigger

iTrader: (16)

Duration and valve timing is the concern. You can get away with a good sized cam on cathedral port motors with stock or near stock valve sizes, but the square port ls3/l92 style heads have much bigger valves and cannot take as large of a cam. There are tons of threads on this in the Gen III internal modifications section. Do a search and you will find many many threads on what cams and sizes you can run without fly cutting.

Doug G

I should have included that info also....

LS3 heads shaved .050
Stock bottom end LQ4
Cam on a 110 lsa w/ .624 lift

boot85

iTrader: (2)

So what is the total lift that stock springs will handle?

speedtigger

iTrader: (16)

Stock springs are junkers. I have seen magazine dyno tests where there was valve float on the stock cam with stock springs at around 6000 RPM. They replaced the springs and picked up 10 or 15 HP and 500 RPM.

Aftermarket springs are only about $150 bucks for good one and about $230 for really good springs. Most guys like the PAC brand springs. I run them too.

Doug G

Anytime you swap a cam there is a good reason to include springs...especially if the motor has some miles on it.

boot85

iTrader: (2)

That was what I was thinking too.