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Old 10-10-2008, 11:10 AM
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High Compression and "The Pump"

I'm planning on replacing my heads on my 383 SBC because i have 882's right now and dont like them. SO i have a set of 186's that i was planning on putting on. This is where my dilemma is. Here's the specs on the engine:

76 Block => 383
Eagle Esp 3.75 crank
5.7 rods
Speed Pro Flat Top Hypers (i think 5cc dishes)
Comp Cams 268H

So the 186's have a combustion chamber of 64cc's so that puts my SCR at about 10.6:1 and my DCR is 9.8:1 with the cam straight up and 9.6:1 with the cam 4* advanced. This is the part that worries me. From what i've read, DCR should be 9:1 or lower for pump gas. Is there anyway that i can run pump gas with the setup i have now? I know i'll probably have to retard the timing a bunch and i am shooting for a quench of .040".

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Old 10-10-2008, 11:21 AM
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You will be fine if you keep it below 9.5:1 CR on pump gas at 93 Octane.
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Old 10-10-2008, 09:09 PM
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Anybody else have any opinions? I was thinkin about swappin out the cam for somethin bigger like a 280H. That would bleed off some pressure and get my DCR down to around 8.9:1.
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Old 10-11-2008, 12:42 AM
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Sell the 186's and get some 70-72cc aftermarket heads.
Performer RPM WP Sportsman II IK 180 (70cc) Iron eagle 200 Platinum

You'll go faster without excessive compression ratio.
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