Ok, like the topic states I would like to hear your input on my engine build, Its a bit of a copy of what car craft just did for their saturday night slayer but with few different key pieces. Let me know what you think. Keep in mind this is a strict budget build.

SBC 4bolt main .030 over
383ci with 400 crank and Speed pro forged pistons
8.99:1 compression with current heads
920 Casting heads with 2.02in and 1.6ex valves installed and screw in studs
Summit budget cam .465/.465 lift 282/282 duration
1.5 Ratio Roller Rockers
Gear drive
Edelbrock Performer Intake
750 Holley DP
HEI Ignition

I bought my 91 RS with this engine in it. The bottom end was built with these head on it. I pulled it out and found a VERY small cam inside and every gasket leaking. So Im throwing it back together with the new cam. I think it will run alright. The carb might be a bit to large but thats an easy fix. Let me know your take on this build and what you might change. Im not buying new heads or changing anything radically. This is just a tight budget build designed to make some decent power.
Thanks for reading.

 

Wrong cam, no mention of headers? or exhaust system details. Performer RPM or similar would be helpful, rather than a smaller carb.

 

Why is the cam wrong? I am running shorty headers with a full 3 in exhaust no cat.

 

It's a 9:1 383, that's why. If you want to keep the stock computer with no tuning, and if you have too much rear gear and a loose converter, if applicable, then it could work. But Vizard is correct in noting that strokers with poor heads ( even with 2.02s, you're still worse off than stock 1.94" Vortecs ) you need a tight lobe separation. Consider the Isky 270 Mega cam, Same lift, close-enough duration, much tighter, 108-degree ( not 114! ) lobe sep. If the Isky has 4-5 degrees of advance ground in, great! If not, get a 3-key timing set.

 

This build is no longer computer controlled. I understand that vortecs flow better however the 920s are what I have to work with. Tell me specifically why the cam I chose is wrong and what disadvantages I will encounter so I understand better. Do realize that this is just a mild street build. Im not looking for gobs of horsepower or I would have changed the entire top end. Also Cam Quest recommends a camshaft very similar to the summit 1104. By their estimations The car should make 330hp.

 

Your lack of overlap is hurting the headers ability to increase cylinder filling. You get less mid-range torque and top-end HP. Your later intake closing is hurting low-end torque. You're not gaining anything useful at any RPM. Going by desktop dyno is fine IF you correct the inputs to compensate for the errors. Go find a half dozen known builds, magazines or my best builds will do, and put them into DD. Look how far of DD gets the predicted results, versus real-world results. For DD2K I can tell you exactly how to compensate. For newer versions of DD, I have no clue.

 

Ok by the looks of it and more research. Low compression 383 stokers require tight lobe separtation (as you mentioned) and really dont perform as well as one might hope. So... if i were to upgrade to vortecs that have been machined to allow .550 max lift and would bump my compression up to just over 10:1, what cam could or should I be running. My rear gear is currently 3.27 so im gonna have to change that but Im not sure when.

Or if the I keep the current setup, what can I expect from the Isky 270 mega cam. I found a similar comp cam with 110 lobe separation PN 12-211-2 which looks like it should work well. Thoughts on that as well. I would rather keep the current setup since the budget is small.