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New to the forums here. I’m stuck on cam choice for my car. It’s a special variant of the Chevy SS. LS3 with a 6l80e transmission.
I’m not sure what is a good choice. The car has some work done to it and has a small cam currently but wanting to go bigger.
Some info on the specs:
*Ported 0821 cast heads.
*Upgraded valve train (BTR-002 trunnion kit, ls7 lifters, upgraded beehive springs etc)
*Large over the radiator air intake with standard ls3 manifold and throttle body.
*It has 4 into 1 headers with dual 3 inch stainless exhaust and high flow cats. Pretty sure the cat back steps down to 2.5 inch at the rear. I have had the bimodal valves refitted.
*It has a truetrac centre with the standard 3.27 gears.
The trans has the standard 1600 stall converter I believe, but I just had Circle D build me a 2800 stall 10.5 inch converter. Already been delivered and ready to go in.
With the cam I’d like the lsa to stay around 114-116 and overlap to be at 0 or negative. PD boost friendly would be nice aswell.
In terms of a cam what I was thinking was a custom cam 224/236 with an LSA of 115 with +3 advance.
That should give it 0 overlap and put the IVC at 44 and the EVC at 56. Are these valve events okay? Is the duration split too big, should I lower it to a 224/234 or even a 224/232?
I ran a 224/234 116+2 in a TVS 2300 blown LS3. Really liked it. With stock heads, the rig made 660 rwhp with boost at 9.5psi. If I had a do over on that one, the cam would have more duration on the exhaust side. Something like a 224/240 would have added to the top end without inducing too many crappy mannerisms. With full boost available just past idle speed, the bottom end of the rev range will take care of itself.
I have a similar cam in my current N/A LS3. It's a Cam Motion custom 226/234 115+4 with .620 lift on both sides. Just changed the valve springs on that one after two years and 30K miles and everything looked great. Wouldn't be afraid of lift like that. That was also with stock rocker arms and they looked good too.
I've had Pat G spec a blower cam or two for me in the past. On PD blown LS engines, he always had the DCR around 8:1. Not sure where that would put the IVC, but I wouldn't want to close it too much earlier than that...especially with a heavier car to move.
I had an SS a few years back. Loved the car...hated the weight. Had I kept it, a Heartbeat TVS was going on. They should have come factory equipped with a p/d blower.
Thank you for all that input. The 224/236 does seem to be what I am looking for.
Since I won’t have a supercharger install anytime soon. Do you think that it will be still good for a n/a setup? I’ve heard that the rectangle port heads like a larger duration split.
And with the lsa of 115 with +2 advance would that be okay once a supercharger is installed? Or should the lsa be adjusted?
To get the DCR I used the Wallace racing calculator. I input the info but to get the right IVC you get the adv duration minus the duration @ 0.050 then divide by 2 and add the the ivc? Is that correct? Going off the calculator the DCR seems to be coming out at around 8.02:1 to 8.1:1.
I'm sure you'll be fine. Converter will help get her moving. Your cam is on the conservative side enough that the bottom end will be fine without the 'charger. The LS3 I had with the 224/234 116+2 cam would accelerate real nice even out of boost. Yours should be better.
The DCR calculator I use takes "advertised duration" input (.006 lift?). I've been using Cam Motion to source my cams and they told me to add 54 degrees to duration at .050 to get to advertised duration. I didn't plug your numbers in, but I'd bet the different calculators are really close.
Would have been nice to have the stall fitted first. But wasn’t expecting to get one. I’ve emailed Cam Motion and got a reply stating he’d like see a bit earlier intake close event in a N/A setup. He requested further info as I didn’t give all the specs and awaiting a reply now.
I’d just thought I’d look further into what’s been done on my car. Regarding the cnc ported 0821 heads, the heads have also been decked 0.030 and are fitted with the GM 0.051 head gaskets. So the compression is increased. I don’t know how much bigger cam I can go. I would like the ptv clearance to not go lower than what’s recommended and I don’t want to flycut the pistons.
You have good guidance with the CM guys. Give them all the specs and I'm sure they'll get you lined out. You might get your tuner involved about now too. Full boost at just over idle is going to change things vs an N/A setup. All of that is just more than a little bit above my level of understanding.
So Cam motion got back to me with their recommendation.They said 229/244 lsa 118.5+4. I remember seeing a video of Brian Tooley explaining a PD blower cam should have around these valve events.
That gives it an overlap of 0 and valve events of:
IVO: 0
IVC: 49
EVO: 64.5
EVC: -0.5
Just not sure if I want to go 229/244, I was thinking maybe something a bit smaller.
Decided to contact Pat G see if he can help me. I’ve heard he’s one of the go to guys for cam advice.
Thanks for posting a cam thread, nothing is as much fun as thinking about cam timing. My engine runs perfect, and I *still* wonder what I’d gain/lose by tweaking my valve events 2 degrees this way or that. 🤣🤣🤣
I have a custom spec’d cam from Cam Motion in my LS Swap 1965 Cutlass. She is a torque monster down low.
Cam Specs: 224/236 .595/.595 112+3
Engine: L96 6.0 iron block with flat top pistons
Heads: LS3s
Intake: Truck
Trans: 4L80E with FTI 3200 stall
ECU: Holley Terminator X Max
Excited for a new cam swap. Especially with the Circle D stall.
That’s a nice build SLWRDE thanks for sharing. Definitely would be a torque monster!
I’m currently in the process of a catch can install. Found one I like and got a custom bracket for it to bolt onto the head. Finally got all the lines cut and fitted with the attachments. Just need to install it now.
08-28-2021, 11:47 PM
LS3 Cam recommendation 
