Final grit to finish cylinder wall?
So Im going to hone this little Honda engine with that 3 stone honing tool. But the stones look too rough for a final finish. Does anyone have an idea what grit cylinder walls are finished with? Im not buying a $50 flex hone to rebuild a $100 engine, ha.
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There are finer stones out there,,but I do not remember the number...getting old I guess.:judge: |
Ok cool, thanks Glenn. I have another question for you, if I have to take off so much material that I need an oversized ring, can I run an oversize ring with a standard piston?
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I have heard of this being done. More than once. It depends on how much material you take out. Clearly it's not optimal, but within a thousandth or two it's not too bad. |
You must mean a hundredth or two. I could sneeze a thousandth off the cylinder wall.
Before hone - 2.662, after - 2.672. Thats exactly 1/100. Im going to just run a standard ring, I took more off the Vette motor when I blew up that last piston. |
That's actually a lot that you took off and will cause the piston to slap around. Are you sure about the measurement? The Probe pistons I run in the Cobra call for a clearance of .003 - .007. I had Dick finish hone the block for .005 because I'm not running an intercooler. That's what I had on with the 302 as well and it didn't have piston slap nor did it scuff the piston skirts even with how hard I ran it.
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.007 piston clearance is a .014 larger bore. And .03 sounds dangerously tight to me for forged pistons. I've heard of up to .012 clearance/ .022 larger bore.
I'd rather run too much clearance than not enough, without question. I've never heard of a piston rocking itself to death. Same with piston rings, I filed mine to the largest tolerance allowed. Who gives a fuck if it costs me 5hp? I dont want it binding when I push it heat soaked on a hot day. But anyways... compared to my SBC pistons, this little Honda piston has NO room to breathe. There is no rocking back and forth, in fact with the bit of rust that formed I had to smack the piston out of the hole with a hammer. Hard. So Im not terribly worried. If it was closer to .02/ .03 I would have gone with an oversized piston. |
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Most over size rings need to be filed to fit correctly. You DO NOT want the rings ends to butt when hot---that will rip off the top of the piston |
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The Mahle rings that came with my engine kit were not file fit rings but the end gaps were all over the place. They ranged from .008 up to .016. |
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The .004 per bore inch is general rule and is different for forced induction and Hypereutectic pistons........:p |
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.012 piston to wall clearance. Or .024 difference total. Meaning, if I had .003 clearance, and I opened up the bore .01/ or .005 on each side, I now have .008 piston to wall clearance, and it's well within spec for a forged motor. So Im not worried. |
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If you measure the piston and then measure the bore, that's the clearance. It's not half, what makes you think that the piston stays centered in the bore?
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And then you divide by two... ?
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Why are you dividing by 2?
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Im not, I havent even checked it. I thought you would divide by two, makes sense no?
Either way, if .012 is good enough for a forged car engine. It's good enough for my pressure washer engine. Ha The collective input from engine experts in this thread is now worth twice what the engine is. |
Dividing by 2 would only make sense if the piston stayed centered in the bore but it doesn't. The piston moves around in the bore as it travels up and down and with load changes.
.012 is too much piston to wall clearance. A forged piston needs more clearance than a hypereutectic piston does due to the greater heat expansion. Probe recommends .002 - .0075 for their forged SRS pistons depending on bore and application where as they recommend .001 - .0055 for their high silicon FPS pistons. |
You may be right about the way its measured, but Im telling you, Ive seen a .012 spec for a forged piston.
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:cartman:
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Where are you measuring your piston at? In all those examples they are measuring from the pin center and not from the skirt where the piston is wider. Even in the first example for the CP pistons it says that CP recommends .004 when measured from .005 from the bottom of the skirt but that he guesses that it would be .011 at the pin.
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Update, this motor is a 2007 GX200 and I guess theyve changed since then. So I wasnt able to locate a HG or even piston rings for it. So I cleaned the stock stuff and just copper sprayed the HG. Runs like a champ.
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