allen said:
when you hit a wall at a lower rpm level that you expect theres almost always a miss-match in components, or a clearance issue or a failure to have the tuning set up correctly,restricted fuel delivery or an ignition curve that won,t advance are usually suspected, but it can and is common for lack of valve control to become a limitation in many cases. Id also point out that a restricted exhaust (especially if you run catalytic converters) is a very common problem as cats get clogged over time, so testing for exhaust back pressure is a mandatory test as that's a common issue. you didn,t mention, headers, exhaust system drive train gearing , car weight , tire diameter,ignition advance curve, timing,etc. now that cam is very similar to a CROWER 00471 that I've used in several engines and I know it easily supports 6200rpm in a correctly set up 383 ,a cam with 234 duration @.050 and that lift you list should if properly installed and matched to about a 10.5:1 compression ratio, and a rear gear in the proper range to allow the engine to spend the vast majority of its operational time in the 3000rpm-6200rpm range , work really well.
the air gap dual plane intake manifold right out of the box will also allow a 383 to reach 6000rpm, so if your ignition advance curve is correct, and fuel pressure steady at at least 5.5 psi, that would make me suspect a restricted exhaust or a valve spring or valve train incompatibility issue, you can verify the exhaust back pressure thru testing, but one thing that seems to be a big red flag here is the valve train. which is an all to common thing to over look, the valve springs and clearances must match the cam and lifters being used and clearances and load rates must match the application
READ THRU THESE THREADS
viewtopic.php?f=52&t=181
viewtopic.php?f=70&t=4683
viewtopic.php?f=56&t=495
viewtopic.php?f=52&t=1070
viewtopic.php?f=52&t=82
the heads are rated for a .550 max lift and the cams got a .548 listed max lift, thats very close or in fact may be getting into clearance issues and thats a hydraulic roller cam, operating with valve springs that may be set up to match a flat tappet hydraulic cam, in fact the heads instructions state!
E-STREET™ S/B CHEVY FEATURES:
Feature as-cast ports and are designed for entry-level street performance 1955-86 applications
Designed for use with hydraulic flat tappet camshafts only, not compatible with hydraulic roller camshafts
http://www.edelbrock.com/automotive/mc/ ... ainers.pdf
THE SUGGESTED, SIMILAR HEADS HAVE VALVE SPRINGS WITH SPECS SET UP FOR A .575 max lift
150 lbs.SEAT
1.800"
420 lbs. @ .580" MAX LIFT
1.460" 1.060" 1.150"
those heads have, significantly lower seat and max lift LB ratings from what I see in a quick search
Installed Height (in): 1.800 in.
Seat Pressure at Installed Height (lbs): 120 lbs.
Open Pressure (lbs): 310 lbs.
ID also suggest checking exhaust back pressure, with a gauge and use of an infrared temp gun while tuning
viewtopic.php?f=56&t=495
heres the one I use and recommend
http://www.testequipmentdepot.com/e...1100200223789&utm_content=All Extech Products
INFRARED TEMP GUN
you might be surprised at what a few tests show you and how much time and money you can avoid wasting
http://www.harborfreight.com/fuel-pump- ... 93547.html
http://www.summitracing.com/parts/pro-66776/overview/
you should measure the exhaust back pressure, a clogged catalytic converter would cause similar issues
obviously if the cats inner exhaust converting matrix block melts from a leaking head gasket or overly rich exhaust , it becomes very restrictive to exhaust flow, killing power, and thus ,it must be replaced
http://garage.grumpysperformance.co...ckpressure-hurting-your-combo.495/#post-22402
http://garage.grumpysperformance.co...ng-high-flow-cats-on-exhaust.8401/#post-29318
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