Spark knock

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April 9th, 2018, 05:56 AM

Jascriber

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Join Date: Mar 2018

Posts: 5

Spark knock

Hi all,

I’m having some trouble with spark knock in my 68 442 (stock rocket 400 engine). I’m running premium fuel, but it still knocks under acceleration. Any suggestions on what could be the culprit? I was thinking of going to a PerTronix ignition system to see if that helps. Thanks for the input.

April 9th, 2018, 06:26 AM

cutlassefi

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Join Date: Nov 2008

Location: Central Fl

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Quote:

Originally Posted by Jascriber

Hi all,
I was thinking of going to a PerTronix ignition system to see if that helps. Thanks for the input.

That would have nothing to do with it. The most common problem is too much advance for fuel being used and/or an improper air/fuel ratio under load. Add to that potentially a cooling issue but changing the way the ignition is triggered will do absolutely nothing.

April 9th, 2018, 06:31 AM

allyolds68

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Location: Seneca Falls, NY

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Quote:

Originally Posted by Jascriber

If you're running points the first thing I would check is the dwell

April 9th, 2018, 04:20 PM

Jascriber

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Join Date: Mar 2018

Posts: 5

Thanks for the help guys. Adjusted the carb mixture and adjusted the timing. Took care of the problem.

April 9th, 2018, 10:28 PM

droldsmorland

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Join Date: Jul 2010

Location: Land of Taxes

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This is what I run in a similar car, same engine, W30 like cam, HEI distributor, auto trans, 2700 stall, 11:1 comp, sea level.
12-14* base timing, another 8-10* on the advance can the rest all in at 2800 for a total of 38ish. Then adjust the vacuum signal to achieve the highest reading possible at op. temp at 700-750 curb idle no vacuum leaks. I run 91 or better non-ethanol with 104 boost occasionally. Never knocks.
What plugs are you running?