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My 383 had a problem getting hot, sluggish performance, and rich exhaust smell,sooty plugs, I got an aluminum radiator, big flex fan, a 4.5 power valve, jetted down to 65's in the primary, checked the float levels, timing 10 degrees initial 33 total advance......no results......until. I decided to advance the timing "by ear" What a difference! Stays at 180, she pulls hard up to 6 grand, idles beautiful, no smell, plugs are a light brown, I'm not even going to put the light on it.....just gonna clean her up for the Woodward Dream Cruise.
 

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Well, first of all 33 total is not nearly enough. Retarded timing contributes to overheating. You may have lucked out adding 5 more and "found" 38 by accident. It's by no means proof that timing lights are not needed.
 

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And timing marks are often times way off. Some of the aftermarket chinese balancers many are using are slipping their rings frequently. Verify TDC and also mark your pulley so you can monitor if things are changing.
 

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For every successful anecdote of "timing by ear" there are ten horror stories.
Here's one about my buddy:

He had an old Econoline w/ straight six. Timing mark was difficult to see much less monitor while turning the distributor. Out of frustration he set the timing by ear because the old farmer that helped him told him it was the best way in his experience with old cars. Said it ran fine but soon developed a bearing knock.
A few weeks later called me down to give my opinion. The farmer and he had the engine out and the pan off. They wanted me to look at the bearings and tell them what caused the unusual pattern.
It had the classic signs of detonation showing with heavy wear on the tops of the rod bearings and on the bottoms of the mains. The piston tops had tell tale signs as well.

I told him he had excessive pressure hammering the pistons on the compression upstroke. He said he didn't hear any loud spark knock so he thought it was ok.
Farmer looked a little sheepish when I explained the science behind spark advance. My friend looked sick about his hurt engine laying in pieces

You will see many web sites perpetuating the same old farmer adage that advancing the spark to knock and backing off is best. It is NOT.

Spark knock (over advanced timing causing audible knock) occurs before TDC. It has nothing to do with peak pressure after TDC.

Best spark advance is one that allows peak cylinder pressure 12-15 degrees after TDC. Over advancing the timing can create excess pressure before TDC and not hear an audible knock. There is no way downward pressure on a rising piston is good for the engine much less performance.
 
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