Thread: advice on piston crown pitting
06-03-2009, 05:18 PM #1
advice on piston crown pitting
i have just pulled the head off jump boat as the last time i was out she kept stalling when hot,but always started straight away on the button.
anyhow thought best to pop the head off for a look incase it was something else,on closer inspection all three bores are great but the wash looks a little rich as expected as i left it fat and two out on the highs but she peaked at 1 1/2 but this is a fun boat so i thought better safe than sorry...
has anyone come across this pitting before and if so what was your findings,
its #3 which is pitted,should i forget it,replace the piston,ect..
no history of any failure on this boats engine what so ever and still runs strong....
thanks in advance and looking forward to hear what you guys say
vf11's,carbed 1300,advent,running 1200 ignition,150 psi across,riva f/a's
edit.just cleaned the dome on #3 after taking a few pics and there is a tiny tiny ammount of pitting around the squish band area..tiny ammount not like piston crown
Last edited by Hydrotherapy; 06-03-2009 at 05:29 PM. Reason: further info
06-03-2009, 05:40 PM #2
06-03-2009, 06:02 PM #3
06-03-2009, 06:05 PM #4
06-03-2009, 06:18 PM #5
guys are there any engine internals i can afford to loose out the exhaust port without having to worry..
06-03-2009, 07:13 PM #6
for some reason that just looks a lot like deto to me...very minor though..
Crappy gas maybe?
06-03-2009, 07:23 PM #7
those look like signs of detonation to me.
read this thread
if it were a piece of metal, it would hit surfaces all over the head in a sporadic pattern in different depths. This is looskliek signs of abnormal combustion.
Has anything changed?
- premix ratio
- gas selection
- advent settings
06-03-2009, 07:25 PM #8
06-03-2009, 07:26 PM #9
06-03-2009, 07:28 PM #10
remember, as temperature increases from [engine cooling or fuel mixture], so does your chances of deto
Also, extra back presussure can increase deto.
Too lean of a mixture can also increase deto. temps run up, chances increase.
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