View Full Version : 351 w 85 S&S sluggish and small back fire

07-27-2013, 11:33 PM
I will start with all the new parts. New plugs, new blaster 2 coil. New petrinox E I ignition, new distributor cap & rotor button, new plug wires, new holley marine carb, new Sherwood water pump.
The boat ran great today for the exception of the sluggish hole shot and it would also back fire at the same time. I will note that it doesn't do it all the time. It started doing it at the end of the day. Any good advice would be appreciated.

07-27-2013, 11:43 PM
Did you check ignition timing after installing the petronix?

07-27-2013, 11:46 PM
You may have the mechanical advance not returning to it base idle position due to worn advance springs and/or corrosion. Too much advance will cause the backfire. Take the distributor cap off and take a look. You can also check timing advance using a timing light. Is it possible that you didn't tighten the distributor and it is moving around a little?

Backfires may rupture the power valve on marine carbs made before 1989. Check yur power valve and consider installing Holley 125-500.


07-28-2013, 12:11 AM
Yes the timing was good after the distributor cap was changed, but I did notice there was a little slack in the cap , not much though. I am pretty sure that the advanced springs r weak. Thanks I bet that will fix my problem.