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Discussion Starter #1
I'm rebuilding:
289 bored 30 over,
RPM intake,
600CFM edelbrock carb
351W heads, exhaust ported
duals with 2 1/8 pipes,mufflers,
headers
when I change from a performer cam (204/214, 448/472) to a more aggressive cam
XEH 256 (212/218, .477/.484) the hp drops???
Is this correct??
 

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Chilly is correct. The problem is that you have too much exhaust restriction and the Comp Cam is bigger and is ground on a narrower centerline, which all adds up to more overlap. Overlap works great to boost volumetric efficiency on an engine with open long tube headers, but with restrictive exhaust it simply exposes the intake tract to the backpressure that's present in the exhaust system and results in intake reversion which kills power on both ends of the power band. If the exhaust system isn't big, free flowing, and thoroughly optimised, usually a cam with wide lobe seperation angles and run with 4 to 6 degrees of advance will perform much better. It's the same reason that many people have found out the hard way that going from the stock 116 lobe seperation cam to a hotter 110 or 112 degree l/s cam an otherwise stock 5.0 with stock exhaust will only slow the car down. Try playing with numbers a bit on your program. Put your intake lobe centerline at 108 - 110 degrees and your exhaust at 120 - 124 degrees and look at your results. It'll give you a good idea what kind of cam you should look for to match your combination. You could also throw the specs for Ersons M/P1 grind, part no. E211011 The specs are 208 - 214 intake and exhaust duration @.050 and .28 and .299 intake and exhaust lobe lift, with 108 intake centerline and 120 exhaust centerline. I'm thinking your engine should like it.
 

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Discussion Starter #3
thanks. I'll look up that cam and plug it in. I assume you are talking about the advanced mode of Engine analyzer. That is a little over my head. I really want a quite, sleeper so to speak. My program shows the preformer cam to get about 291 hp, SO, maybe it will be 270 or so....thanks for the info, i only want to rebuild this thing one time.
I'm porting heads now... builds more character than hp I believe!!!!!
 

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Here are the complete Erson E211011 specs.

******** Intake Exhaust
Seat duration 280 292
Duration .050 208 214
Lift at valve.448 .478
Lift at lobe .280 .299
lobe centers 108 120
total lobe seperation 114 degrees
cam comes ground with 6 degrees of
advance built in. That should be all
the info you need.

<font size=-1>[ This Message was edited by: mach1morgan on 1/23/02 1:19pm ]</font>
 

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Discussion Starter #6
Where can I buy an Erson cam or what is their website. I cant find it with the search engines i'm using....
You were right, I picked up about 5hp with this cam over the performer.!!!
 

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I can give you a phone number. I think it's for Ersons Tech line, but if nothing else, I'm sure that the guys in Tech can get the order line number for you. PH.775-882-1622
 
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