Cutting down a piston????
09-06-2007, 03:42 PM
#1
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Location: Ramona, CA
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Cutting down a piston????
So, my engine builder was finally buttoning up my motor, putting the pistons in and the Speed Pro pistons he had ordered were just barely too tall for the block. Anyone ever have this happen.. The guy said it would probably not hurt anything, just that the compression would go up a little, and I could have some valve slap.. But we decided to go ahead and shave down the tops of the pistons to fit correctly.. Anyone see any problems with that? Im not sure what the part number is of the piston..
09-06-2007, 03:50 PM
#2
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Location: California
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RE: Cutting down a piston????
Hmm..well...lets see...all the heat is on the top of the piston as well as the piston compressing your air/fuel mixture. I guess it depends on how much meat was cut off & how much is still there. How can the pistons be to tall? Did someone shave the crap out of the deck?
Rick
Rick
09-06-2007, 05:28 PM
#6
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RE: Cutting down a piston????
ORIGINAL: RobbieG.
If your talking.005 or .010 it would be ok. Anymore than that I'd be looking for a differant piston.
If your talking.005 or .010 it would be ok. Anymore than that I'd be looking for a differant piston.
How is it that your engine builder didn't take this into account? Either these pistons are designed to be like that, or your block has been decked way too much and you could possibly have intake sealing issues.
09-06-2007, 05:30 PM
#7
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RE: Cutting down a piston????
decked block is what it sounds like to me, what motor is this? maybe a 302 crank with 289 rods or something? that would stick em outta the hole.
your head gasket is about .040 crushed, so you can get away with a little sticking up - but you have to "****" the piston side to side and measure how far it was sticking up there, not just when the piston is centered in the hole @ TDC
your head gasket is about .040 crushed, so you can get away with a little sticking up - but you have to "****" the piston side to side and measure how far it was sticking up there, not just when the piston is centered in the hole @ TDC
09-07-2007, 02:06 AM
#8
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RE: Cutting down a piston????
Im not too sure,, how much it was sticking up.. I would guess about a finger nails worth.. Probably between .025-.030 of an inch.. They decided to just mil the pistons,, You know,, i was thinking about the crank Idea.. and the guy who sold me the car did say it was a 302 from the begenning,, but maybe it was just built with a few 302 components.. I dont know.. I will have it back tomorrow to sit in the garage for another week so that I can weld my shock tower cracks up... and then finally get her back in and running... Im getting depressed just thinking about having to wait even longer... But hey,, I thought I wouldnt get this dont until October , so I guess Im actually ahead of schedule..
The glass is half full for now,, at least until i do something like burn a big hole through my shock tower with a mig welder...
The glass is half full for now,, at least until i do something like burn a big hole through my shock tower with a mig welder...
09-07-2007, 07:36 AM
#10
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Location: Citrus County, FL
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RE: Cutting down a piston????
is the motor supposed to be a 289, or 302?
if the motor is still on the stand and the oil pan is off you could check the casting numbers and see WTF is going on there. a 302 crank should be a 2M or 2MA if i remember correctly, and a 289 crank would be a 1M (again, IIRC)
if the motor is still on the stand and the oil pan is off you could check the casting numbers and see WTF is going on there. a 302 crank should be a 2M or 2MA if i remember correctly, and a 289 crank would be a 1M (again, IIRC)
