502 carb gen1V eating pistons question
08-22-2017, 09:08 AM
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502 carb gen1V eating pistons question
I bought a boat with 1 rebuilt motor in it. Shortly after running it. I had 3 pistons with holes in them. Assuming someone didnt set timing correctly. I had motor rebuilt. Since the the motor has been out 3 times with bad pistons. What gives. I have timing set at 8degrees. Seems to run great. The longest it has run is 4 hours. Since rebuild. Anyone else run into this. Im guessing ignition module?
08-22-2017, 09:36 AM
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when you say eating pistons do you mean detonation that caused holes in the pistons?can you give more information like what exhaust system and any thing that is not stock in the engines.also,have you checked to see what the total ignition timing is set at?have you put a fuel pressure gauge on it to monitor you,r wot fuel pressure?
Last edited by mike tkach; 08-22-2017 at 09:39 AM.
08-22-2017, 09:47 AM
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Motor is stock. Looks like from detonation. I have not run fuel pressure test or total ign timing yet.. As soon as i get it back togather. I just wondered if the ign module cauld cause this
08-23-2017, 08:39 AM
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Carb ? EFI ? What hp rating ?
If carb, you don't by chance and mistakenly (seen many do this) have the mechanical fuel pump vent hose hooked up to a vacuum source do you ?
Edit in:
If carb, which one ?
Has it been the same exact cyl's that get holed each time ?
What spark plugs are you using ? MR43T's ?
If carb, you don't by chance and mistakenly (seen many do this) have the mechanical fuel pump vent hose hooked up to a vacuum source do you ?
Edit in:
If carb, which one ?
Has it been the same exact cyl's that get holed each time ?
What spark plugs are you using ? MR43T's ?
Last edited by SB; 08-23-2017 at 08:43 AM.
08-23-2017, 09:21 AM
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What is the intake ? sounds like a fuel distribution issue
08-23-2017, 09:24 AM
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Pic shows this.
Still make sure fuel psi is good at WOT.
Last edited by SB; 08-23-2017 at 09:28 AM.
08-23-2017, 10:12 AM
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inside on one, outside on other bank? Like 1-7-4-6 or 2-8-3-5? Bad carb. Primary (front) venturi too lean on 1 side. Other side runs good, and provides enough power to let the bad side roast the pistons. Run a single plane intake and roast all the pistons slower but evenly. Or replace, repair the carb.
