[gm383]

Had my boat engine fail this past weekend, burnt up all the pistons- ring lands broke at the thinest point of the piston.
600hp small block with edelbrock 170gph pump and matching reg.
Driver reported 'surging' and down on power that got progressively worse until he shut it down.
fuel filter canister was clean, no blockage. 2 -10 lines to the filter housing, 1 -8 line up to the pump with an inline check valve.
What could cause the 'surging' ??

 

[000Racer]

Pistons burning up caused the surging... Was most likely lean or timing changed..to much...

 

[000Racer]

Lean will cause surging.

 

[gm383]

Lean will cause surging.

OK great, that helps. Before the race we drove the boat to start line (i was in the boat for this) we sat on 30mph @3500-4000 rpm for 20 mins to get there, and the afr gauge read 12.0 the whole way, both cylinder banks?

 

[000Racer]

OK great, that helps. Before the race we drove the boat to start line (i was in the boat for this) we sat on 30mph @3500-4000 rpm for 20 mins to get there, and the afr gauge read 12.0 the whole way, both cylinder banks?

Was it surging then?

 

[mufflerguy]

Do you monitor fuel pressure? Was the surging a dying fuel pump, hence all the burnt up pistons?

 

[gm383]

Was it surging then?

No it felt and sounded fine.

 

[gm383]

Do you monitor fuel pressure? Was the surging a dying fuel pump, hence all the burnt up pistons?

Driver reported the gauge was at 6psi. I was wondering the same- bad fuel pump?
carb/timing hasn’t been touched?

 

[000Racer]

Likely was lean at wide open throttle.... What carb?
Jets, how about more info on the engine.

 

[jeff swisher]

I had the pleasure of tuning on a 427" SBC that was surging many hours of tweaking with no sucess and discovered it was fuel octane related.
Stuck some 112 into it and no more surging.
Did you accidentally stick the wrong fuel into it?
That would cause all your issues.

 

[gm383]

Likely was lean at wide open throttle.... What carb?
Jets, how about more info on the engine.

6.0 LS running a distributor conversion. 12:1 comp Australian pump 98 fuel. 4150 carb with 1.58 Venturi 82-94 jets and 8.5 pv
Super vic manifold

 

[gm383]

I had the pleasure of tuning on a 427" SBC that was surging many hours of tweaking with no sucess and discovered it was fuel octane related.
Stuck some 112 into it and no more surging.
Did you accidentally stick the wrong fuel into it?
That would cause all your issues.

Possibly bad fuel. Just from the pump unfortunately

 

[gm383]

 

[mufflerguy]

Tune or fuel? You can see in the second pic, you were about to lose more ring land at 2 o clock. As well as one hole looked dead, judging by the soot.

 

[000Racer]

Too lean, too much timing, to hot a plug.... What heat range plug?

 

[gm383]

Tune or fuel? You can see in the second pic, you were about to lose more ring land at 2 o clock. As well as one hole looked dead, judging by the soot.

All pistons were on the way out, all starting in the same place (thinnest part at the valve relief)

 

[gm383]

Too lean, too much timing, to hot a plug.... What heat range plug?

NGK 9

 

[000Racer]

Maybe ask how thick the piston is where the valve pockets intersect the ring land.... May have just been too thin... Did anyone cut the pockets deeper?
Who's pistons ?

 

[gm383]

Maybe ask how thick the piston is where the valve pockets intersect the ring land.... May have just been too thin... Did anyone cut the pockets deeper?
Who's pistons ?

CP bullets. They are unmodified

 

[000Racer]

Ok, any sign of the ground straps on the plugs starting to melt??
How much timing was run, what ignition?