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Old 08-26-2012, 01:34 PM
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Originally Posted by vinniekq2 View Post
what,
toddalin said,,,and a dynojet dyno usually reads lower than a mustang chasis dyno. 12.8-12.9 af is great for the street.It would make more power with open exhaust and a little richer. so lets say your engine is 400 ish hp. for sure a good guideline to build 400 hp. My favourite carb for small v-8s like 327s is a 4777 with 4781 base plate and a few tweek
s like replaceable air bleeds and minor contouring etc.

Its a great share offering your parts list and actual dyno figures.
In this other set of dyno runs that include A/F ratios, in every case the leaner pull made more power at any point on the RPM band. That's why I went 1 jet leaner on the secondaries.

Initially I tried 2 jets leaner on the primaries, but that created a lean surge while cruising. I returned the primary jets and it cleared right up, so took 1 jet size from the secondaries. Taking it from the secondaries also "squares up" the mixture better as it enters the manifold.

Also, this clearly illustrates that the "bog" is created by an over-rich condition (note that the A/F drops to ~10:1 at the point of bog), rather than a lean spot as most infer. The PO of the carb was trying to chase the bog and, based on conventional wisdom, put in the 28 squirter in the secondaries. The 25 in the primaries is standard. When I changed to the 21s the bog went away, though I've not done another dyno run to see where the A/F now is at this point. But the SOP, says much improved. Note how smooth the A/F ratio is past this point.

I recognize that the dyno is NOT THE STREET and most jet a bit richer for the street to account for unknown variables and load factors that come into play. But, my A/F ratio is still safe, and a slightly leaner mixture also typically improves gas mileage and throttle response.

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Old 08-26-2012, 02:10 PM
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newbie here building a 327 looking for atleast 400 hp.....HELP!!!!

Rock_Dog, Start out with a 327 block bored .030, decked to 9.005. Your crank cleaned and polished. 5.7 rods reconditioned or new I-Beam rods, flat top pistons IC792 are forged, KB100 are Hypereutectic. Your compression ratio with 64cc chamber heads IC792 is 9.8, with KB100 is 9.6. Choose one of these cams 12-676-4, XS268S, 1600-6000, .488/.501 lift and 230/236 duration @ .050 110 LSA or 12-220-5, 270S-8, 2000-6000.495/.495, 235/242 duration @ .050, 110 LSA. Edelbrock Performer RPM intake and a Holley or Demon 750 DP. HP should be from 425 @ 6000 rpm w/XS268S, 433 @ 6500 rpm w/270S-8. Torque 420 @ 4500 w/XS268S, 414 @ 4500 w/270S-8. With the block being decked use a Fel Pro .039-.041 head gasket to net 44-46 Quench. See toddalin's build sheet for how to finish setup.
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Old 08-29-2012, 08:42 PM
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Thanks so much cdminter59! thats the kind of lay out i was looking for!
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