I've got a forged 383 with a good set of ported stock heads and a comp cams XE 224/230 on 112 ICL. The car is a LT1 WS6 6spd. The thing drives and pretty much idles like stock, and runs out of steam before the 6400rpm shift point I would like. Since the cam is so tame, I feel I am giving up too much HP with this cam.

So, I called Combination Motorsports and they recommended the 236/242 cam or possibly the 233/239.

My question is:

Will the 236/242 cam cruise on the highway well at 1800rpm? I'll be going to 3.90 rear gears in the future, which will bring the highway rpm up, but for now it has to handle 1800rpm in 6th. This is important, as the car sees many highway miles.

Can someone give me their experience with this cam at that rpm in a 383? If it won't cruise well, I'll get the smaller 233/239.

Thanks!

 

I have a larger cam than either of those in my 383 and have no noticeable cam surge at all. The secret is in the tune.

 

That cam should rev higher no problem.

What is done to your heads? I think they may be your limiting factor.

Do not try to overcam to compensate for the heads or you will lose low end as well as not get the top end breathing that you desire.

Good heads & moderate cam is always better than the opposite.

 

My 233/239 is mild in a stock cube motor. Lopes like a mother, but drives fine. I'd DEFINETLY go bigger in a 383

 

Lonnie,

The heads are fully ported LT1's with port, bowl, combustion chamber work(unshrouding larger valves). Head flow is still increasing between .6 and .7 lift. Flow at .6 lift is 266/194 at .7 it is 270/203. Not as high as some out there, but fairly decent.

The 224/230 in the 383 really does run like stock engine. You have to listen really close to tell its not stock. This and the fact I feel power is peaking before 6400 would lead me to believe I could use a bigger cam. The 224/230 does make TONS of torque down low, though and is a blast on the street.

I selected this cam for a stock displacement engine, but when I tore the engine apart, I decided to do a forged 383.

My goal is for around 400rwhp, high 11's in a stock weight 1997 T/A at 1650ft elevation. I then have a 150 shot of nitrous I will add on that. I've spent tones on the car and engine, so I really want to get the most out of it. The only stipulation is that I do about 35 highway miles a day and 3-4hr trips on weekends, so it has to cruise well at 75 and get better than 15mpg.

I value you opinion, as you gave me good advice when I was supercharged, so do you really feel the 224/230 is the best choice for my 383 with the heads stated above?

 

I had the EX 236/242 in the stock bottom end 350ci. The dyno graph is in the sign. The cam was very driveable, even w/ my 3.45 gears. I personally wouldn't wanna go much bigger. The trick with this cam (and all EX grinds) is having a valvetrain that will prevent valve float.

My cam will be for sale in a couple of weeks. PM me if you're interested.

 

I did the same exact thing you did, I started out with the 224/230 XE inmy 383 (auto though). and it seemed way way too tame. I switched to the GM 847 and gained 6 mph in trap speed and over a half a second in the 1/4.

Its idle is very nice, noticable lumpy, but smooth. The power is instantaious, and still there all the way to my self imposed 6500 rpm redline.
I've been told the cam you have picked is simular.

 

I have the 236/242 is my forged 383. I haven't driven it much, but untuned, through a moser 12 bolt and a steel driveshaft I put down 390 rwhp and 381 rwftlb tq. Not too impressive, but hopefully once I get it tuned it SHOULD (key word, SHOULD) do ~420ish I'd guess, maybe more. Who knows, Only time will tell.

 

Your heads will be the determining factor.

 

I'm also running the XE236 on the stock bottom end. Sound clip if you need it...

 

I have the 236/242 ground on a 110lsa in a stock LT1 with EX612 springs and with Ion's tuning it drove like it was stock!!! It'll be up for sale in the near future while Im doing a rebuild. It has less than 400 miles on it.

-B