The setup is:

-355 block
-AFR 195cc heads
-Edelbrock Performer RPM manifold (or Airgap)
-AFR hydra rev kit
-Holley 700 CFM double pumper carb

Which of these cams would be better:
-Comp Magnum hyd roller: 224/224 @.050, .525/.525 lift
-Comp Xtreme Energy hyd roller: 230/236 @ .050, .510/.520 lift

One has more duration, the other has more lift. Which do you guys think would be better for this setup? Thanks in advance.

 

define "better".

 

need some more info, compression ratio, auto or manual, and car use...

 

Sorry for the lack of info guys.

Compression is 10:1, 700R4 trans with a 9.5" 2600 stall converter, 3.73 gears, lots of traction, car use is almost daily driver, but goes to the track often.

By "better" I mean something with a flat torque curve that will give me the best achievable track time :-). Thanks again.

 

I'd probabily go with the larger second one, of the two.
The carb is too small.

 

Need to know about your exhaust system.

Why these two options for the cam?

Do you have all the listed parts already?

 

I wouldn't go with anything other then the X-treme cam designs, the are superior too the old slow ramp cams.

 

I agree. Go with the XR282, it's a vastly better cam than the older design one; it runs real hard in my car, you can believe that. The difference isn't so much in the lift & duration alone, it's in the shape of the ramps. And the carb is borderline too small; use a 750, especially if you haven't already bought it.

This will like large-tube headers and a free-flowing exhaust. Get rid of every single piece of your LG4 stuff, from the heads to the street; use a set of 1¾" headers and a high-flow cat and a 3" cat-back.

 

i agree w/ the two before... go w/ the xe282... better ramp rates... and if you went w/ the smaller one you would be wishing you had the bigger one sooner or later...

 

His carb is not too small.

 

. Boom 540lift.

 

Well I actually already have everything, including the XR282 (the 230/236 cam). I had an injection setup that I hated with this setup, so I ditched it and went with the carb setup. I wanted to double check to make sure the cam I have will be good with this setup. I quesioned the other one because AFR used it and got 453 HP at 6000 RPM. I got the 700 CFM carb because it was an awesome deal on ebay. I don't think it's too small. If you look at the formula (CFM required = (CID x Max RPM)/3456), and use 6500 for theoretical max rpm, I get on 668 CFM on my 355, and that is asuming 100% efficiency, which won't happen. I have an article on this issue somewhere, I'll try to find it. As for my exhaust, I have the Hooker 1 5/8 shorties, with 3" all the way back, no cat. Now from what I have been told, you determine the header size you need by looking at the size of the exhaust valve. Since my valves are 1.600" and my primaries are 1.625", it should in theory be okay, right? Thanks again.

 

And BOOM....more duration. 1.6 rockers do not only increase the lift, they also add more duration to the cam, almost the same profile as the amount of lift that is added.

 

Only one problem if I go to 1.6 rockers....I know I'm gonna run into valve/piston clearance problems. I already had to give my valve reliefs a tiny shave on all my pistons to get the correct amount of clearance.

 

I suppose that .540 lift is outta the question then. Unless you want to tear the block apart again to install dished pistons....

 

Good grief, what is your deck height at?!

 

I have seen emprical data supporting this.. (like a cam-analyzer spec sheet)


So, your telling me that you have sufficent clearance for .525 lift but not >??

Since piston to valve clerance is normally about .110" minimum, I surmize that you will have less than .1" with the 1.6s. Its very unlikely that its being cut that close. However, if its possible, just add 1.6s to the intake. Exhaust piston to valve is normally the one that is closer and more crucial with heat and expanision. Most manufacturers indicate that intake clearance can go as low as .080-090 with no problem. if you cut the valve reliefs more than .165" deep, there should be no problem.

 

My block was zero decked, and the heads were milled down to 64cc chambers. Believe me, the .510/.520 lift was CLOSE. That's why I had to shave the valve reliefs a little. Thanks for all the replies.

 

what thickness head gasket are you running???

 

Rarely does any thing hiperf have factory valve relief depths..
Most are .165" (even factory) and hiper aftermarkets tend to be +.25" minimum. If these are OEM or replacement pistons, you are at the mercy of the smaller cam.