i'm working on putting my 93 back together and have decided it will be a 383, mild port job, long tubes, bolt ons, anyone have any good ideas on the cam. The car is an auto with a 2800 stall, 3.75 gears. It is also speed density. I have some ideas of my own, but would like to see from experience what is working, so i can see if i'm heading in the right direction. Had a LT4 hotcam in my Z28 a few years ago would like a lil more than that

 

Man, are you going to get a lot of differing opinions and recommendations on this one!

Here're mine:

Get a CompCams catalog. Look at the lobe profile pages toward the back of the book and find the hydraulic roller grinds that have the Constant Radius of Curvature lobes.

If your heads and exhaust system are of the high flow variety, choose single pattern cam lobes; if not choose a dual pattern with 6 degrees more exhaust duration that intake duration.

230/236 or 236/242 would be the two ranges I'd look at. With your gears and stall, the 230/236 would be a better choice. This is because of the way I look at cams; that being it's better to have a cam too small than too big. Once you cross over the 230 duration range, vacuum becomes an issue and power brake problems begin to creep in. Idle quality goes south with the longer duration cams too.

Look carefully at the offerings and choose the lobes that offer the greatest lift vs duration. Subtract the .050 duration from the advertised duration: the smaller the result the more aggressive the lobe. Aggressive is what you want.

When compariing one cam against another, make sure the advertised durations are measured at the same lobe lift; that way you're comparing apples to apples.

I'm sure you know that speed density it's going to take kindly to durations in that range.

Just my thoughts.

Jake


[Modified by JAKE, 4:31 PM 7/13/2002]

 

i second what he said, 224/230 is about as small as you'd want to go with 230/236 being what i'd favor as well. make sure you have at least 10:1 compression. the lobe lift you use will depend on your heads. the stock LT1 head without excessive work really doesn't like to flow much over .500 lift so a .503/.510 grind would be perfect. it also makes valve springs cheap

 

I have experimented with desktop dyno and found that you need about 10 to 12 degrees on the exhuast side. You probably want a custom ground cam. Shoot for 226 - 230 intake and add 10 to 12 degrees to that for the exhaust. Go for a 112 LSA and run the intake centerline at 107 - 109. Lift will depend upon the duration. I found that wider LSA kill the topend and midrange. Some guys have suggested 114 LSA but the loss in overall power is not worth the smoother idle.

Crane has some good lobes and so does comp cams. Use lobes designed for street use that emphasize stability. Be sure to use the valve spring recommended by the cam mfr and put titanium retainers on the valves. Use hydraulic roller lifters. The solid ones are not designed for street use and fall apart eventually which can lead to an expensive engine failure.

I am about to try out the custom cam I got ground by crane. Its spec'ed at 230/242 @ .050 duration and 539/558 lift with 1.5 rollers. 112 LSA and 109 intake center of lift. Desktop dyno gestimate for hp is just under 490.

 

The limiting factor will be the heads. Match the cam to how well the heads flow. :yesnod:
:chevy
Half

 

I would go 230/236 or even bigger on the 383ci you would be just fine. I had custom ground Extreme Energy cam 222/230 @.05 .560/.600 on my 383ci blown motor. Its idle fine and very means.


Bruce
93LT1 Conv w/ZF6
blown D1-SC/N2O
ARE built 383ci/Stage II head