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Discussion Starter · #1 ·
I have a 302 with a e303 cam and aluminum heads. I've been trying to set ignition timing and the "happy place" that I have found is 25 degrees advanced. I've been reading a lot on this matter and most seem to be running 12-16 degrees. Every time I back off timing it starts to run rough, and then when I turn it back up it runs fine. I've had no issues with overheating and so I'm stumped.

Does anyone else on here have the e303 cam and/or is anyone running ignition timing in the mid 20's? I also have an msd distributor with a 6a electric ignition (so no vacuum)...any thoughts? I appreciate the feedback.
 

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I've been playing with mine last couple days. Discovered I was coming in too early. I run all mechanical on my 302, MSD 6A and pro dizzy, no vacuum advance. Assuming you're running 9.5:1+/- compression, that should put you at roughly 38-40* total, no more. I'd recommend all in by 3500rpm, and 16* initial. You need an advance timing light to set this up. The bushing and spring kit for the dizzy is less than $20. Use the bushing to set the total limit, and the springs to control how fast the timing advances. The springs are colored, two light silvers will bring it all in by 3k rpm, light silver spring and heavy silver spring should put you right at 3.5k rpm. Purple bushing should limit you at 22-24* (+16* initial = 38-40* total.
 

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Discussion Starter · #3 ·
Groho, I was checking total timing tonight and at 3,500 RPMs I'm at +/- 42 degrees. Like I mentioned, my issue is I can't turn down the ignition timing without causing the engine to stutter and run rough. With that said, I don't think it's the distributor springs unless I'm missing something. Any other thoughts?

How bad is it to be running at 25 degrees ignition timing if the engine is running well and at a reasonable temperature?
 

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I'm thinking your balancer has slipped. Find TDC to fire and mark it on your balancer. Dollars to doughnuts, it will not line up with the "0" on the balancer. If this is the case, you can put a timing tape on your balancer using your TDC mark. (Put a dab of clear nail polish on the seam to keep it from peeling off.) Or, you could install a new balancer which would be a good idea if yours is original.
 

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Could be that you need to check your idle settings on your carb. Setting idle is a balance with the carb and timing.
 

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Groho, I was checking total timing tonight and at 3,500 RPMs I'm at +/- 42 degrees. Like I mentioned, my issue is I can't turn down the ignition timing without causing the engine to stutter and run rough. With that said, I don't think it's the distributor springs unless I'm missing something. Any other thoughts?

How bad is it to be running at 25 degrees ignition timing if the engine is running well and at a reasonable temperature?
Initial timing is not as much of a concern as total timing, but 25 is high. I am with @groho, your total is a tick high. Given you are not running vacuum advance, more base timing does not surprise me. Groho's plan seems logical. I would start there.
 

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I would also say your mark is off or you have the wrong pointer on your timing chain cover. Pull #1 plug and find tdc to verify.
 

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Its a balancing act, as you adjust timing, you need to re-adjust idle speed and air/fuel mixture. If you can't get under 25 initial, that also likely means you can't get to 900 rpm idle. I'd take a serious look for a vacuum leak. Or, a damper thats jumped timing as Klutch says. This sounds nuts, but go back and check your valve lash to insure they're ALL the same, one or two rockers TOO tight will cause similar rough idle; or bad cam lobe.
 

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I am in agreement with the others. The elastomer rubber allows the outer ring to slip and the timing marks are off. Timing has nothing to do with rockers or carb settings. Rough running does.
 
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