Thread: 383 bumpstick question!

Tweet

Quick question. I am building a 383 street/strip engine with 9.8:1 comp, sportsman II heads, Edelbrock Perf. RPM, and 750 demon carb. Im gonna run a hydraulic roller cam and so far, the Comp XR 276 (224/230 dur/ .536/.544 w/ 1.6 roller rockers) sounds like the best mix of Hp/Tq. My question is, would this cam be any milder in my 383 than in a 350? does displacement matter or will the cam sound and perform the same? Also, would you recommend maybe a more agressive cam? I want to be able to hear the cam and be able to rip it up at the strip after its daily driven weekdays. Thank!!

comp cams has good grinds i would call them and get a recommendation

Choosing a cam is the hardest thing to do unless you just turn it over to the "cam techs". They'll inevitably steer you to one of their shelf grinds that is a compromise on a 110 LSA. I've been reading a lot of Vizard's writings lately and he STRESSES that a 350 works best with a 108 LSA and a 383 works best with a 106 LSA. I'm also going through the same thought process with my 389 sbc. My heads flow about the same as yours and my cam(218-228 on a 112 LSA hyd. roller) leaves a lot to be desired. Good street manners but all done @ 5000. I'm probably going to have a custom cut @ 230-242 on a 108 LSA with a 108 centerline. The 108 is my version of a compromise. Everything I've seen with a 110 or wider loses a lot of torque below 3500. This, I believe, is the primary reason why everyone pushes CR increases to get some of it back. You just need to be realistic about the intended usage of the vehicle and don't get carried away with the duration. Small heads like ours need more overlap to better fill the larger displacement.

i have read up on LSA's with bigger displacement but always thought that a 106 grind would be too much for daily driving. It would make for a killer 383 though. I guess i would just have to take it easy like you said with duration and i would have a killer torque curve. Im gettin excited just thinkin about it!!

I saw a curve on a 383 with a 215-224 on a 106 LSA. It pulled 12 inches at idle but fell off the face of the earth at 5200. Thick torque everywhere-make a hell of a street cam. My only street driving is to the track and back so I'm going to stretch the duration to reach 6000 and compromise the LSA to 108 to be barely streetable.

yep, i would go with a 108 or 110 at the most, considering most shelf comp cams come in 110. Do you think a duration of about 226/230 would put me past 5500 rpm. I was kinda aimin for about 6000 also. what kinda et's are you runnin on that cutlass of yours?

My best time is 7.97 @ 87mph w/1.74 60'(1/8mi) but it usually runs low 8's. I'm pretty sure about the 230, 226 probably will too. As far as LSA's, the wider ones will hold on longer than the narrower ones will as a rule. Our heads flow about the same(vortecs) from what I've read so they are going to make power up to 5500 approx. Since I'm almost exclusively racing, I want to shift at 6000 even though my HP peak is 5500. I shift at 5500 now. If one is doing more street driving, a shorter duration will be "nicer". Ironically, most street driving is below 3500, which coincidentally is where the 110 and wider cams give up torque.

Thats must be a hell of a ride down the 1/4!! Someday ill make a pass that fast...even if it means crouchin in the trunk well after thinkin it through, im down to either the Comp XE 276HR or XE 282HR. Either one is a winner but ill probably go with the 282 to get a couple more rpm/hp at the strip and have that killer idle on the street!!

Super chevy has some info on cams.What kind of power curve are you trying to get?

Wait a minute dude. Those times are 1/8 mi. If I went 7 seconds in the 1/4 mi I'd probably soil myself. According to the conversion chart I have, 8 flat in the 1/8 mi is the equivalent of about 12.5 in the 1/4 mi. Almost respectable but my goal is very low 12's all motor to stay out of roll bar territory. It is fully street legal right down to the egr valve and catalytic convertors. Then if I decide to strap on some hidden squeeze...... Anyway, Hot Rod magazine did a feature on a 383 with vortec heads and they slid a XE282HR in for 463 flywheel HP at 5600. It pulled 12 inches at idle but lost 25 lb-ft below 3500 due to the 110 LSA.

im tryin for about a 2800 to 5800 power curve captain. 25 ft/lbs isnt all that bad considering it probably more than made up for it higher in the curve. maybe i shouldnt get too greedy with the duration and go with the XE 276HR. Hmm...... decisions, decisions... Chevy HiPerformance Mag did a 383 called the twister that pumped out 480 ft/lbs with that same 282 cam. It was quite streetable with 436 ft/lb at only 2600 rpm, maxing out at 486 ft/lb at 4200rpm. Im hopin this power will get my 3300lb nova in the high 12's considering im gaspin for air myself at 3600' elevation!!!

The duration issue changes when you spread the LSA. By going wider you can run more duration and get away with it. That's why the companies routinely do it. Either of those two cams will get you what you're after. They should put you solidly in the 12's.