I'm planning out a 383 and from the looks of it for a month or two it will have the stock 350 heads, i know this will hurt my cam choice but i dont want to have to swap the cam a 3rd time when i eventually do upgrade the heads, is it worth it to get the 276, or will the the 268 be a better choice? I'm planning on around 9.5 compression with the current heads. It seems that the 276 nets more HP at the sacrifice of torque, but playing around in desktop dyno it seems the 268 always has this advantage over the 276 with both torque curves just moving up, which cant be right because that would negate having so many cam choices to begin with lol.

Chirp08,

I am no cam expert, I leave that to others like Harold, Mike, and the crew. I can state this, that may be of help. About a year ago, I built a 383 that had stock heads (1.94, 1.50) that were ported and cleaned. The valves had undercut stems, and a 3 angle valve job. We used a Energizer cam, adr dur 274, .450 lift, and the rpm range was listed at 2200-5200. The static compression was 9.5, or very close to that. The engine was balanced, but he only planned on taking it to ~5500 rpm max. He had full length headers, with a High rise dual plane intake. The carb was a SA Holley 750 cfm. The owner wanted a lot of low / mid rpm pull. The first thing we realized is that this cam was too small for the 383, but would be great for maybe a 350. We later put on 1.6 rockers, which clearly helped and gave the engine a little rumble. This summer he plans on putting a better set of heads on, using the same rockers and cam. It will be interesting to see what effect it has.

Fred.

too small? Wow, i would think if anything too big...

Does it have a lack of lowend, because the 268 greatly outperforms it down low, at the sacrifice of maybe 20 peak hp. I'm assuming that the stock rockers are 1.5 ratio?

Yep, the stock rockers were 1.5, stock factory type. It has tons of low end and mid range power. Once it hits towards the 5K mark, you can see that it needs a better set of heads (if you kept this cam). When he had the 1.5 rockers in, it almost seemed like it was a mild sounding 350. The 1.6 gave it a bit of a rumble, but you can tell it's a mild street engine. It rev's real quick, and from 1 to 4.5K it pulls very hard. You can see it peaking right after that, but it still pulls. Jim's goal was to be able to pull stong to 5.5 K or close to that. We originally were thinking of what would be a good cam for a 350 and then stepped it up one level. Even with that, that cam was still mild.

Fred.

wow i guess thats why so many people are running the xe284 / voodoo 284. I thought it would be too much cam for anything under 10.75 compression, but real world experience is where its at.

Doesn't a 383 generally redline at 6000-6500 anyway, i dont see why he would be lingering so long around 5500 to hurt performance that much.

Chadwick,

We did all our original dyno testing in a 9.2:1 CR 355. Cams like the VooDoo 276 and the 284, and their Xtreme Energy counterparts, over-cammed that low-CR engine. All 4 of these cams need a 10+:1 CR to really come alive, although even in the low CR engines, the VooDoos out-performed the Xtreme Energys, across the RPM band. An 383 at 10.5:1 and a 3000 SS converter would love the VooDoo 276, and a 10.5-11:1 383 with a 3500 stall would love the VooDoo 284, which really is a big cam.
I like the VooDoo 268 and a 2500 Stall for most street driving.
My daughter drove an 1984 Camaro Berlinetta with a 9.2:1 383, 195cc AFRs, original Performer(this was in 1992...), Carter 625 AFB, stock converter, stock rear gear, A/C & PB. She drove it for over 5 years, then it soldiered on for another 3 with other owners. It ran 8 years on the same cam, lifters, springs, etc. I used an UltraDyne 266/276H12, 211/221 at .050, .441/.454 with 1.5s, but we had Crane 1.6s for .471/.485, and 112 LSA.
She was 15, and in the 10th grade.......

UDHarold

Harold,

To persue this a bit more, is it the small valves that makes the 274 cam seem so small in this 383 (ignoring the added Cubes)? It seems to have a smooth idel, almost a stock idel, as is. I expect a major change once a larger valve, better flow set of Alum heads are added.
To add one more question, when most cam manufacturer list their RPM, idel, etc, is this based on the cams best calculated compression, the largest heads, Carb, etc on a 350 (355), if it's a small block cam? (thanks)

Chirp08,

Jim wanted to keep it low, around 5.5K because he expected it to live a lot longer. I've seen 383 cranked to 8K without a problem (so far). On the Cam, you right, just as Harold pointed out above. You can calculate the best Compression for each Cam. Running too far away from this set value, hurts performance, depending on the setup, etc.

Fred.

Yeah so im guessing the 268 would be ideal for a 383 that will run at 9.5 or so compression, and later 10.5 with better flowing heads?

Chrip08,

The equation you would use to see if the cam you have selected is correct for your engine is:

Static compression ratio needed =

Total swept Volume + Total chamber Volume
-----------------------------------------
Total chamber volume.

So the cam, and the intakes closing degree, plus the type of gas your running, plus cubes, etc all tell you if that cam will respond well in that engine. There are several other items that interplay, that's why I was hoping Harold would jump back in, or someone would add the missing details.

Fred.