The new combination I am going with is quite a bit different than the norm so I need some help picking a cam. I am building a 457ci LSX for my 2003 silverado ss. My truck is AWD, weighs about 5,300lbs and has a 3000 stall. Truck must be able to run on pump 91 octane. Specs on the motor:

LSX block
-LS7 heads (stock intake side, but the exhaust has been reworked by WCCH)
-Ported LS7 manifold (jeremy Framoto)
-4.200" bore
-4.125" stroke
-6.125" rods
-Custom CP pistons with a reverse dome of the ls7 combustion chamber
-SCR of roughly 11.2:1

I have been hearing from some knowledgable and experienced people (with the ls7 heads) that the ls7 heads do not like huge cams. I have also been told that a smaller cam would suite my truck better because of 5,300lb wieght it has. Anybodys opinion with experience with the ls7's heads would be greatly appreciated.

 

I heard there was a new 454 ls block out there by world mot. Is that what you will be using? Gonna be a bad ride!
Derek

 

I'd say search over on tech. I've had a 422 and 427 in my 4x4 sierra with 3 different cams. All were on the larger side (244/244 612/612 112, 252/258 612/612 112, 240/244 608/610 111). I don't know about the LS7 heads but with that size engine going with too small a cam would be a waste after spending so much time and money on the rest of your set up.

 

That is quite a tough call due to your setup being built with alot of newly released parts and stuff. I'd roughly guess:


236º/252º
.630"/.630"
112 LSA

What are the flow numbers on the heads?

 

Zippy, if I told you the exhaust side of the heads flow in the 250cfm range at .600 lift (after richard at WCCH ported them) rather than low 200's would you still recomend such a huge split on the duration?

 

No, this is a brand new block from gm called the LSX capable of 480ci for half the price of the warhawk block made by world. The world block is alluminum though compared to the iron LSX.

 

Not at all. That is some excellent flow for an exhaust side. Thumbs up to Richard. I'd say roughly the same spec's, but something around:

236º/238º
.630"/.630"
112LSA

The big advantage to big flowing heads is that you don't need nearly as much cam.

 

Wow, that's almost the exact same cam richard recomended me. One question though. Do you think a 112lsa will give me enough vac for the brakes etc.?

 

I would say something in the 240 range should easily give you a lot of top end and keep plenty of low end at the same time. Just keep the LSA tight, nothing bigger than 112 and it should be a great running engine

 

also can I ask why you are going with such low compression for that size block?