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Old 04-10-2011, 08:25 PM
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troubles with Demon Jr 525

I recently installed a new 525 Demon Jr on a 283 Chevy. The trouble that I am having is that it won't idle and is hard to start. I have done all the adjustments and nothing helped. I come to the conclusion that I had a vacuum leak. By holding my hand over the primaries limiting the air flow I could get it to idle. So I took the carb off and replaced it with a edlebrock that I had and it runs fine telling me that it is something in the new carb. I disassembled the carb looking for a vacuum leak. Found that the secondary diaphram was bad replaced that and all the gaskets still have the same problem. I have tried different base gaskets and that didn't help. Anyone out there have any ideas?

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Old 04-10-2011, 11:18 PM
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Is the demon new or used? If it`s new you have to clean the idle passages out before it`ll idle. Every new demon I ever delt with has cnc shavings in the idle passages from the factory. When you hold your hand over the carb and it idles correctly means the idle is set too lean which goes hand and hand with the idle circuits being plugged.
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Old 04-11-2011, 07:15 AM
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I will try that Thanks
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