How do you determine actually how big of a came you can go with.
my car came with a lt4 hot cam, but im switching from tpi to carb, and in the process also going to throw a bigger cam in.

help is appriciated. thanks!

 

The springs on your heads are rated for so much cam lift. Plus if you get too radical, you get into vacuum issues.

 

With a carb there isn't much limit.
You want the stall speed on your tranny to match (upgrade that at the same time), and your rear gears.
About a compxe 270hr would probably be a good range to be.

 

i already have gears 3.23's.. a vigilante 3200 stall. 350 .30 over. trick flow heads (twisted wedge). 1.6 roller rockers. federal mogul pistons/rods. polished crank. and currently have a lt4 hot cam.

the car had a accel superram,tpis bigmouth mani.24lb injectors and a 52mm tpis throttle body. and im throwing a 650-750 dp, with probably a wiend team g manifold on it.

thats what im asking is how big of a cam can i go too.

 

Ah, gotcha.
That the 190cc heads?

ooh, a polished crank, goodie haha, j/k

I think the xr270hr is a good area to be in. I'm not familiair with the LT4 hotcam tho anyway. You *can* go even bigger, but how bit are you willing to go? The xr276hr is probably about the limit unless you upgrade the stall speed and go to 3.73 gears. the xr282hr would be a bit of a bear without those upgrades, IMHO.

That's just 'cuz I have memorized comps lineup. Crane etc would be similar.

 

The comp XR276hr cam is a proven cam for a 350. 224/230 @ .050" there are all kinda guys running in the `11s with this. I've got cam and lifters for sale w/ less than 3k miles on them. PM me if interested.

Seth

 

Is the one you have for sale more radical than what i have now. im looking for more lope than anything. this motor was built by the guy i got the car from. so when it goes im going to build something way differant, but i have the front bumper off so i thought it would be a good time to change the cam.

 

beleive me i was thrilled too!

 

I have the xr 282 hr in a 350 vortec. 15 inches of vacuum and I ran it for a while with the stock converter as a daily driver. It would idle with the a/c without problems. Most trick flow heads can handle that lift too. If you want something a little better matched to the engine though, you might want to look at this....
http://store.summitracing.com/partde...1&autoview=sku
This cam is dyno tuned to trick flow heads and will be a little close on enough vacuum for the brakes. Great throttle response. Just to be safe a vacuum canister is always a good idea with a bigger cam.

 

Almost forgot...
xr 282 hr 230/236 .510/.520
lt4 hot cam 218/228 .525 .525
You won't notice a big jump in power, but the 282 hr has a broader power band. And as for 11's.... It would be possible. I get 12's and I know my carb is a little off. That's with a 2,800 stall and a 3.42 rear.

 

but would it be more radical sounding?

 

All of the cams mentions will sound more "radical" But as far as a street car I wouldn't go much bigger than a 224/230 in a 350. That 224/230 had a pretty good idle (mildly rough) in my 383 so it would definitely sound mean in a 350.

Seth

 

The xr 282 hr does good on the street. Mine is sounding decent, but I have an open exhaust right now. With my idle at 650-700 it had a little bit of rumble to it before changing it to open headers, but it's not unbearable. I think a 650 carb would be better then the 750 I have though.

 

I think the 750 should be fine if you get it tuned right. I am actually going to a 950 dp with my new cam (280/286 @.006" 232/238 @ .050" .580" lift) I was running a 750 dp before w/ 75/84 jets and the 950 has 76/86 jets so I dont think it will be too bad.

Seth

 

decisions decisions.... thanks for the info!