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As I was coming back from fishing yesterday, no we didn't catch anything, my 1984 BKO had a slight backfire through the carb a couple of times while under a load. I was pulling my 18 foot boat and up a medium grade hill. It's never done that before even on that same hill. Today on the way to work I stomped it and there was no backfire.

I searched and read some of the post but I am at a loss to classify this.
I suspect the timing chain, but I really dont know how to diagnsoe that. I also saw one about a lean mixture backfire. Is there a way to verify it is the timing chain without taking it apart? I adjusted the idle a while back and I went for maximum Vacuum on both sides. Or does anyone have any other suggestions

Coupes ride,
1984 BKO 351 HO, 4BBL, C6, Custome Duals, Glass packs. Dont know how many miles on the engine really the previous owner said the motor was new but....I have had it for 3 years and never had that problem.
If I could spell I would be awesome!
 

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Rest in Peace Friend...
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Well, lean ain't in an unmodified Holley's vocabulary. I doubt that is the problem. The mixture adjustment you made was the idle mixture adjustment. Running mixture is adjusted with jets and a little other fancy footwork to keep things balanced.

Here is a great Holley website that will get you off to a great start on Holley carbs. http://www.bob2000.com/carb.htm

I'd go for a timing problem. Before I got too excited about replacing the timing chain, I'd make sure that the basic timing adjustment hasn't just slipped, like maybe the distributor moved a little or internal distributor parts worn or weak.

(Remove all the plugs so you won't be fighting the compression of the cylinders).

If you want to check that the mechanical timing is close, get a bump switch, bump the engine until it is at TDC on #1 and check the timing marks on the Harmonic Balancer, and that the rotor is pointing to the #1 position.

Once you are satisfied that you haven't jumped a tooth do a regular tuneup following the proceedures given on the emissions sticker.

Good luck,
 
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