Send help.
Driving myself crazy trying to track this down.
I'm running a reverse rotation 305 sbc that I built for my Penn Yan last winter. Last summer the boat ran flawless.
Fired it up this spring and it has a horrible misfire. It's slightly noticeable from idle to 1800. Past 1800 the engine really starts missing. And wont go past 2400 rpm. At 2400 rpms if you try to give it more throttle it just holds there with an obvious misfire, engine speed will not increase (the tachometer will go down during this, even though Ive verified with a timing light that the rpms don't change). It does this regardless of if the boat is in neutral or in gear under load. Under load the boat has lots of power from idle until 1800rpm.
Things we've done:
-Veriffied timing
-Used our spare coil (same results)
-Replaced plugs
-Replaced distributor cap and rotor
-replaced points, twice, made sure swell was 30 degrees
-Pulled the intake, and checked that there were no flattened cam lobes/ damaged lifters
-Performed a compression test (all good)
-Replace intake manifold gaskets
-New Edelbrock carb (same results with the quadrajet that was on it)
-ran an inline electric pump to cancel out a potentially bad mechanical pump
-replaced all fuel filters
-ran without antisipghon valve to make sure that wasn't causing an obstruction
-Boat has 30 gallons of fresh fuel, there was about 15 gallons left over from last season.
The only thing that has not been replaced is the plug wires, checked the resistance on them and they all seem fine.
What am I missing?
I don't think its a fuel delivery issue. And it doesn't seem like there's anything mechanically wrong with the engine.
Driving myself crazy trying to track this down.
I'm running a reverse rotation 305 sbc that I built for my Penn Yan last winter. Last summer the boat ran flawless.
Fired it up this spring and it has a horrible misfire. It's slightly noticeable from idle to 1800. Past 1800 the engine really starts missing. And wont go past 2400 rpm. At 2400 rpms if you try to give it more throttle it just holds there with an obvious misfire, engine speed will not increase (the tachometer will go down during this, even though Ive verified with a timing light that the rpms don't change). It does this regardless of if the boat is in neutral or in gear under load. Under load the boat has lots of power from idle until 1800rpm.
Things we've done:
-Veriffied timing
-Used our spare coil (same results)
-Replaced plugs
-Replaced distributor cap and rotor
-replaced points, twice, made sure swell was 30 degrees
-Pulled the intake, and checked that there were no flattened cam lobes/ damaged lifters
-Performed a compression test (all good)
-Replace intake manifold gaskets
-New Edelbrock carb (same results with the quadrajet that was on it)
-ran an inline electric pump to cancel out a potentially bad mechanical pump
-replaced all fuel filters
-ran without antisipghon valve to make sure that wasn't causing an obstruction
-Boat has 30 gallons of fresh fuel, there was about 15 gallons left over from last season.
The only thing that has not been replaced is the plug wires, checked the resistance on them and they all seem fine.
What am I missing?
I don't think its a fuel delivery issue. And it doesn't seem like there's anything mechanically wrong with the engine.
