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Old 06-11-2007, 08:48 PM
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Will this cam have more vacuum in a 350

I rebuilt a 327 sbc, ran it for a while with a edelbrock performer cam, wanted a little more cam bought a engle ep-22, had good torque good top end but less than 10 on vacuum, Would this cam have more vacuum in the 30 over 350 i have in the nova now, car is a 73 chevy nova street car, motor has been decked in the past cant see engine I.D. on passinger side block i am running 416 305 heads 184 150 valves, port matched, thin head gaskets car runs good now, but i know it would run better with the ep-22, just need to know if it would have more vacuum? Thanks Wormy.

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Old 06-11-2007, 11:14 PM
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I`m guessing it would have slightly more vacuum due to 27 more cubic inches. As for performance, the 305 heads small valves and not so good intake ports are killing all the benefits of the bigger cam, and especially will with more cubic inches.
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Old 06-14-2007, 01:00 PM
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The manifold vacuum @ idlle will not change a lot, if at all.
If you want to maximize the available vacuum, give the motor as much initial advance as it will take at idle. As a tuning excersise to see the effect, temp remove the advance weights and springs from the distributor and lock out the mechanical advance. (two electrical tie wraps work well) Set your timing at 32-36deg BTC at idle. the timing is frozen and will not advance. readjust your carb idle speed and fuel mix screws for best idle around 900rpm. You'll find the idle quality and throttle response is much better. You'll make the most idle manifold vacuum possible.
Now when you get a chance you can remove the distributor and recurve the ignition advance curve. You have to limit the travel of the mechanical advance mechanism from 20 -24deg stock to about 12deg. Use moderate medium tension advance springs so the advance peaks out at about 3000rpm. Set your idle timing to about 22-24deg BTC. Full advance will be 36deg BTC.
Your 305 heads could really benefit from larger 1.94x 1.60" valves and porting.
if you want to maximise low/mid torque with your EP22 cam pull the timing cover and advance the cam a bit to a 104 intake C/L position.
With this aggressive ignition timing use cooler heat range non-projected tip spark plugs in your 305 heads. Champion RV8c or AC delco R42T work very well.
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