Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - running no vacuum advance
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Old 02-04-2007, 02:30 PM
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One thing you have realise is that if you're going to run a aggressive timing curve you'll probabily have to use higher octane gas 92+ even with a 8.5:1 cr. Thats life. Nothing stopping you from taming down the mechanical curve a little (go up in spring tension one one spring) from what your emchanic set up if you find that all in by 2600 is a bit too aggressive. I usually find a good bit of initial (14-16)+ a smooth curve that peaks out (32-36deg) at 3000-3500 is more than enough for a motor like you discribe. I've found thru much drag testing that very agressive timing curves are usually not nessessary to get best acceleration.
This slightly tamer mechanical curve will allow more vacuum advance with less tendancy to ping for exessive advance. You can also go down 1 or 2 sparkplug heat ranges from stock to good effect if you are an aggressive driver. (High performance) This really adds some knock tolerance when running aggressive timing. The stock recomended spark plugs heat range is biased more for around town driving where you need the hotter plug to reduce combustion deposits. WOT driving creates more heat allowing and requireing a cooler spark plug heat range to keep the plug tip form overheating (preignition and detonation) Don't feel you have to run 36deg total either. Many many motors make maximun power with less timing. 32-34deg. Running more timing than what is required to make max power just invites pinging sometimes a little less, is better. Experiment a little. It's all about overall balance.
What cylinder heads are U using? What grade of gasoline? What is the motors compression ratio?
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