383 stroker dyno results

Discussion in 'High Performance Modifications' started by 1974blackz28, Aug 12, 2017.

  1. JasonZE

    JasonZE Veteran Member

    Sep 11, 2009
    my 383 runs the comp 270 cam 9.8 compression 1.6 rockers and e street heads. i have had it tuned and ran 13.6@109 mph 1/4 with poor launches on road tyres.(heavy car with sound deadening, big stereo etc)
    As above tune the engine before changing cams as sounds like your loosing power somewhere
  2. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    Yeah, the overall dyno #s really don't hold a lot of weight. But if when you drive it around and it feels soft or worse slower then the combo you had in the car before something is wrong. I agree with dynos simply being tools to maximize power output, the darn thing could be out of calibration for an accurate # but can still show improvements and regression with adjustments.

    Also don't translate vehicle ET to horsepower. Several factors to include vehicle weight can skew that perception. 250hp will run 11s in the 1/4 miles in the right car.
  3. junkyardZ28find

    junkyardZ28find Veteran Member

    Mar 4, 2012
    des moines, iowa
    I'll add my .02 as to issues I see with your combination. First off, that cam has got to go. .470 lift and you want 450 HP? Nope. For one thing those heads are decent but that cam is not going to let much airflow in to even let them heads breath. IMO you need to be running in the .525-.550 range.

    As for the carb-you say completely stock. Well a stock 750 vac secondary Holley on a mild 383 is not doing you any favors. Since you have it already, no need for a DP with an auto trans....I'd suggest spending a little more $$ on carb mods such as:

    Secondary metering block upgrade

    50cc accelerator pump upgrade

    Try various pump cam profiles

    Strongly suggest going with larger primary jets and now secondary jets with the metering block upgrade

    Try a few larger squirt nozzles

    Experiment with different secondary spring rates

    Theres other Holley tuning tricks but I can say from experience you're leaving a lot on the table with regards to no carb tuning even with that .470 cam....I'd go so far to say you can pick up 20-25 HP on carb mods alone....step up the cam and adjust the carb tuning properly and I think you can see a 60-75 HP increase which puts you real close to your 450 crank HP you're expecting.

    So to summarize, bigger cam and a heavily re-worked carb is your answer...and then my next area of focus would be some ignition upgrades.

    A DP is a great race carb but imo its better to learn some Holley basics and learn to properly tune your "3310" and after that a DP is cake to tune/dial in.
  4. Mwilson

    Mwilson Veteran Member

    MY OLD 383 had 11.4:1 RHS 220's and a comp 288 tls cam made 344 hp & 310 tq at the wheels seemed very low to me too but it ran 11.40's at the track. I didn't like the cam to be honest I feel like I could have done much better with a different cam.

Share This Page