Help! Burned piston
04-25-2006, 07:10 PM
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Re: Help! Burned piston
Originally Posted by MESABALANCING
Chris
30 degrees if timing makes the exhaust temp very hot people think this is safe when it actually does nothing but run the exhaust temp through the roof and reduces engines ability to make power efficiently. I believe and some guys will agree the valve was most likely damaged from heat from a lean condition which was also what damaged the piston I don't believe oiling had any part of damaging the piston either time you may have had bearings fail from detonation but oiling will not melt the piston like that pic shows. Give us some more details about fuel press and fuel oct. and we may be able to help you further. Best of luck in fixing it. Sincerely Laz
30 degrees if timing makes the exhaust temp very hot people think this is safe when it actually does nothing but run the exhaust temp through the roof and reduces engines ability to make power efficiently. I believe and some guys will agree the valve was most likely damaged from heat from a lean condition which was also what damaged the piston I don't believe oiling had any part of damaging the piston either time you may have had bearings fail from detonation but oiling will not melt the piston like that pic shows. Give us some more details about fuel press and fuel oct. and we may be able to help you further. Best of luck in fixing it. Sincerely Laz
04-25-2006, 07:49 PM
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Re: Help! Burned piston
Originally Posted by scarab39
it uses a holley red pump, 6an lines all the way from the tank, through the pump, filter, to the carb. It has 5psi at idle and at cruise, I haven't been able to check at wot as the gauge is at the carb. the engine dynoed at about 660 hp at 4300 rpm. I've had a 'resident expert' tell me that the pump is too small. It has a demon 850 carb. What psi should I be looking for at wot? It has an msd dist and msd marine ignition.
04-26-2006, 07:33 AM
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Re: Help! Burned piston
Smitty is right another thing to check is if the tank or tanks have check valves in them make sure to take them out they can affect fuel flow even with a mak daddy pump and the water temp at 180 also seems very hot you may want to get a small mech press gauge and check the water press and the fuel press at WOT and make sure it's all good before you put it back into service you can get a cheap gauge and run it up to the panel and when your done just remove it . But all things considered you need two more gauges in the dash fuel and water press you'd be surprised the aggravation they will save you.
04-26-2006, 08:16 AM
#15
Re: Help! Burned piston
Originally Posted by MESABALANCING
Smitty is right another thing to check is if the tank or tanks have check valves in them make sure to take them out they can affect fuel flow even with a mak daddy pump and the water temp at 180 also seems very hot you may want to get a small mech press gauge and check the water press and the fuel press at WOT and make sure it's all good before you put it back into service you can get a cheap gauge and run it up to the panel and when your done just remove it . But all things considered you need two more gauges in the dash fuel and water press you'd be surprised the aggravation they will save you.
04-26-2006, 09:21 AM
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Re: Help! Burned piston
When I first installed my motor I added a low fuel pressure switch made by NOS, very sensitive and adjustable, it is located in the fuel log. I set it for 5psi and wired it into the mercruiser alarm and added a prolight.
It went off the very first time I opened the motor up. After numerous changes I now have a Holley Black marine pump with #10 feed and return lines and a fuel log with return style regulator built in. My fuel pressure never varies from 6psi.
Probably overkill, but I was looking for a consistent fuel pressure and that's what it took.
It went off the very first time I opened the motor up. After numerous changes I now have a Holley Black marine pump with #10 feed and return lines and a fuel log with return style regulator built in. My fuel pressure never varies from 6psi.
Probably overkill, but I was looking for a consistent fuel pressure and that's what it took.
04-26-2006, 09:43 AM
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Re: Help! Burned piston
Originally Posted by fbh-velocity
Sorry to interrupt here..., what is best water pressure and where to place the sender.?
04-26-2006, 10:44 AM
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Re: Help! Burned piston
Laz, Thanks for all the info, I'm sure it will save me money and grief! I'll be plumbing a water pressure sensor in the block like you mentioned. What gauge do you use?
***off topic***
Wobble, I noticed you mentioned a mod lite in the past, do you run in houston? I just sold mine, I ran it in houston a few times, but decided I could spend more money boating!!!!
***off topic***
Wobble, I noticed you mentioned a mod lite in the past, do you run in houston? I just sold mine, I ran it in houston a few times, but decided I could spend more money boating!!!!
Last edited by scarab39; 04-26-2006 at 10:46 AM.
04-26-2006, 11:02 AM
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Re: Help! Burned piston
Originally Posted by scarab39
Laz, Thanks for all the info, I'm sure it will save me money and grief! I'll be plumbing a water pressure sensor in the block like you mentioned. What gauge do you use?
***off topic***
Wobble, I noticed you mentioned a mod lite in the past, do you run in houston? I just sold mine, I ran it in houston a few times, but decided I could spend more money boating!!!!
***off topic***
Wobble, I noticed you mentioned a mod lite in the past, do you run in houston? I just sold mine, I ran it in houston a few times, but decided I could spend more money boating!!!!
I was crewing for Dan Sikes and Kyle Anderson on the 54 & 55 TUSA Mod Lites.
This year Dan has a UMP Modified and Kyle has a SUPR Late model. The Modifeid has been a real learning experience, especially the rear suspension geometry, we got a 3rd last Saturday at Baytown against some strong competition. Kyle Broke his arm in Dallas so we wont run the late model until May 6th at Baytown.
04-26-2006, 11:36 AM
#20
Re: Help! Burned piston
[QUOTE=scarab39]Laz, Thanks for all the info, I'm sure it will save me money and grief! I'll be plumbing a water pressure sensor in the block like you mentioned. What gauge do you use?
Ditto?
Ditto?
