chris99gmc

What's up guys.. I'm putting in a brand new 408 Lq9 motor in a few days. I pretty much have two cams to choose from. I'm looking for the best one for my setup. I needs to be street-able, obviously make the most power throughout the range.(I don't care about peak numbers, as much as I care about having a truck that moves from a dig and has good power throughout the range)

ill be be running Ported 243 heads for now, but I'm considering moving to 823's or LSA heads....

the Pistons in the motor have valve reliefs. The two cams I have are already in my possession:

228/230 .571/.576" 112 LSA
239/242 .649/.600" 111.5 LSA

One of them is obviously much bigger than the other. It says it requires a 3500 stall...

I'm running a 4l80e with dual feed and a 3200 single disk Circle D stall(which I don't necessarily want to change)

Opinions?

Vortec350ss

iTrader: (20)

Neither will work particularly well with square port heads. If it was me I would get a new cam ground and sell these 2, but if a choice must be made, run the first cam and get a set of cathedral heads with a really efficient exhaust port. The second cam is too wild for what you want IMO.

Install it on a 109 ICL. It wont rev to the moon, but it will be a bruiser on the street. Expect about a 6200RPM shift point.

oakley6575

iTrader: (5)

Id run the first one too with cathedral heads. If you are really going to switch to rec ports, just get a cam for those heads now.

chris99gmc

So you're saying that the second cam(ms4) with not work well with square port heads?

The Pistons in the 408 have 6cc valve reliefs, btw.

oakley6575

iTrader: (5)

Go look at rectangle port cams off the shelf and compare them to cathedral port cams.. You'll notice the rectangle port heads like a lot more split in them.. People have a lot of dyno time into figuring this out, like Texas Speed.. Id give them a call and explain your situation. But yes, I'd get a rectangle port spec'd cam now so you dont have to do two cam swaps

MikeGM4X4

If you're doing a lot of street driving then I'd recommend going with the smaller cam just for better street manners. But if you live in a rural area without cops then go big!

chris99gmc

Yes. You're correct. I noticed this a long time ago when these heads came into the ls world. It's mostly due to the larger intake runners and much larger intake valves. The cam duration comes largely in to play when deciding on which cnc ported heads to go with as well. Larger isn't always better and there are track times and dyno sheets to prove this. I've learned to overlook things like port flow numbers, bc they truly don't mean dick at the end of the day, unless you're trying to sell. One of the most Important factors of cam selection is being able to match it to your heads/motor combo. This is why I think all the head comparison tests they've done with cnc ported heads is fairly inaccurate. It's bc they don't test them with enough different cams




I live nowhere close to rural. But fortunately I have some buddies who became cops in the area and I'm on good enough terms with a handful of the others, so they don't give me a hard time, like I used to in my younger years. I was only pulled over a few times in the past couple years... Same reason every time.. the officer just wanted to check out my truck.

chris99gmc

Thanks for the input guys... I'm just following the thread up to let readers know that I decided to stick with cathedral ported heads, 2.04" intake valves and 1.55" exhaust valves. ported to 215cc intake / 80cc exhaust.. We'll have to wait and see what sort of Numbers it puts down.