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Author Topic:   Burn't Piston
cas23
Member
posted August 26, 2001 09:41 PM
Last night we blew a head gasket and when we tore it down it also had a burn't piston. Is this related or do we have 2 dif. problems. This is a 2bl. flat top motor. any help would be great.


sdhnc29
Member
posted August 27, 2001 10:33 PM
Odds are , they are directly related !
What cylinder ? Where was the piston burned , Int. side , Ex. side , in the middle ???


cas23
Member
posted August 29, 2001 07:20 PM
it was the intake side of piston that was the worst. but it had melted some around the valve reliefs.


cas23
Member
posted August 29, 2001 07:21 PM
and it was #3 cylinder on a ford


Pickel
Member
posted August 29, 2001 09:01 PM
you also may have run it a little lean..


Scoot
Member
posted August 29, 2001 10:59 PM
My brother burnt some pistons last year. Turned out he wasnt running enough octane. Wasnt able to get octane boost and thats what happend. Just my little 2 cents worth.


sdhnc29
Member
posted August 29, 2001 11:07 PM
Yup !! Sounds like you leaned it out ! If it started to melt toward the center of the piston , this is as a result of detonation , due to extreme cylinder temp from your lean situation . The blown head gasket is probably also a result from either the detonation or the lean situation . I'd start trying to figure out what caused this engine to lean out ! Any other cylinders look bad ? Did it start to lift the ring lands on any other pistons ?


cas23
Member
posted August 30, 2001 03:34 PM
all the other cylinders looked great. and we only ran racing fuel in it. but sometimes we used the cheaper stuff instead of sunoco. i don't know if that would make a diff. in a flat top motor or not. and we only ran the timing at 36 so i don't know why that cylinder would have messed up. and the most the temp went to was 200 while we were racing. if it was lean wouldn't it have overheated?


dreamcatcher
Member
posted August 30, 2001 08:28 PM
no it wont over heat untill it is too late. a couple of years ago i hade the sam prob and did it to 3 different motors, we were running a hogged out motorcraft 2 barrel and the fuel pump was a high volume but not enough, we bought a holly and the the problem was solved. ck the fuel presure. you want it around 6 to 8 psi w/o a presure regulator. hope this helps.



sdhnc29
Member
posted August 30, 2001 10:15 PM
dreamcatcher is correct . The engine does not have to run hot in order to burn a piston from being too lean . If you don't already have a good fuel pump , I would go with his recommendation on this as well . But I would try and keep the fuel pressure around 6psi . When you get this engine back together , I would suggest putting your car on a chassis dyno . By doing this , you will be able to monitor your air fuel ratio , and see if you have a problem anywhere in your fuel system . This would be money well spent !! This will help prevent this type of problem from happening again . Also , you will be able to fine tune your ignition timing . What your engine likes for timing , depends on the combustion chamber of your head , and domed or flat top piston . Most flat top engines will run a little less timing than a domed piston engine . So you might be able to learn a lot , and save a lot by spending an hour or so on a chassis dyno .


cas23
Member
posted August 30, 2001 10:29 PM
ok guys thatnks a bunch maybe now i know what happened. 2 weeks ago we fuel troubles in the turns and we changed the fuel filter and it went away. that might have been what started it. i do have a holley pump and it is a holley 500 that was reworked. boy i wonder if that cheap filter cost us a motor. bet i change those more often.


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