I found the spec sheet from my COMP cam a little while ago. I had some motor goodies put in and I was wondering if looking at the spec sheet, what to look at to see what size my cam is. And if anyone can relate to the size once I comment back, like your cam is medium, small ect...I am thinking I should be looking at the " lobe lift"? which is intake: .3420 and Exhaust: .3400

 

Looking for duration either advertised or @.050 and the LSA.

 

Duration at .050?
Gross valve lift?
Lobe seperation?

 

Valve Overlap.

Intake Centerline.

Lobe Lift(s).


IVO EVO
IVC EVC

@.006" Lift
@.020" Lift
@.050" Lift

 

If supercharged Or Turbo.

Exhaust centerline becomes more important too.

 

ok I will just list what I see.
Intake: Exhaust:
Gross valve lift .510 .510
Duration @ .050 220 230
lobe lift .3420 .3400

lobe separation 114.0
Duration @ .006 tappet lift 276 290

These specs are for cam installed @110.0 intake center line

there are some valve timing opening numbers, let me know if they are needed

 

It seems that you have a "Medium" cam. Maybe what some people back in the day called a 3/4 race. I never did know what that meant.

 

That's a decent sized camshaft for a basically stock LT1.

 

how does it compare to the hotcam? I am new to cams and roller rockers. I had both installed while rebuilding the motor after 188k miles. All I wanted was the lope. And of course the xtra power is nice. I went from 276 to 337hp to the wheels. I love it, and it lopes really good.

HERE IS A LT4 cam spec
http://www.theformulasource.com/foru...howtopic=11725

 

Hotcam 218/228 @ .050, .492/.492 lift, 112 LSA.

 

Are you running 1.5 or 1.6 rockers?

 

Now there ya' go getting technical with a guy that has a "Medium" cam. Geesh!!

 

1.6 rockers might make it an Extra-"Medium" cam.

 

It appears you may have a CC-305 cam used in a supercharged application. This was popular about 12 years ago. I happen to have one sitting on a shelf in my garage. Nice cam for a stock supercharged engine. At the time it put out about 410/435 at the rear wheels.

 

I have 1.6 roller rockers...So when speaking in terms of a cam, you guys would use "lift" as talking about size? like my cam isnt a matter of it being small or medium, it depends on how much lift you have?

Is my cam bigger or smaller than the hotcam. I ask because that was my other option. I am NOT supercharged by the way. Is 276 to 337 a good gain in numbers just off the cam, roller rockers, springs, gaskets, tune and whatever else you would put into a rebuild?

 

With 1.6 rockers your lift is .544.

 

Duration=size.More duration = lumpier idle and higher rpm.That is probably the largest cam I would run in a stockish LT1.The 114 LSA should keep the idle tolerable.
61 hp gain on a fresh motor and cam is good.

The hotcam would pull similar hp numbers but my guess is it would have more torque.

Who did your tune?

 

I did notice I have more power higher in the rpm range on my dyno sheet. I had 303 and jumped to like 330 something after the new rebuild.

With having long tubes, no cats or mufflers, I didn't want something massive but a good lumpy idle was what I wanted. It is the sound I was looking for. It is really loud now but its what I wanted. I just put in my new injectors my FIC and it is running really good now.

A shop called RPM in garner NC did my tune

 

OK Derek, all your cam does is allow the air/fuel mixture to enter the piston area. Lift is how much your valve opens and the more it opens the more air will come in. Kinda like just opening your door at home a little vs a lot in a windstorm. Duration is just how long the door is open. The higher the duration number the longer the valve will stay open and allow more air to enter.

Suppose your lift was .500 or half an inch. If the cam only allowed that lift for a split second and started to close again not much air would be let in. Now assume that the same half inch lift, .500, stayed open for a lot longer. More air would come in because you stayed open longer.

I also think the Hotcam would make similar numbers but would have a bit more lower end power.

 

3/4 cam always meant to me the cam would idle 750 to 950 RPM's.

Full Race to me......,
Open the carburetor throttle blades.... after drilling 1/4" idle air bypass holes in primary & secondary throttle blades.......& at best engine idles at 2,000RPM's without dieing out.



People still used those terms today.