#21  
Old 05-21-2021, 09:07 AM
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PAUL K PAUL K is offline
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Originally Posted by Dragncar View Post
Never thought of bracket racing as class racing. I did take a year off, getting slow.
Any experience with Line2Line ?
I thought he raced heads up in NMCA??

Yes.... Works as they claim. Has a very specific break in procedure. One thing to keep in mind, just because you make the skirt X amount thicker the rest of the piston remains the same. If ring lands are worn that's not fixed. If the area around the rings are worn that's not fixed. At some point if you start building the skirt up a whole bunch your ring dimensions change.... However two thousandths excessive piston to wall clearance can easily be taken care of and may even offer advantages over the "out of the box" clearance without a coating.

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  #22  
Old 05-21-2021, 05:09 PM
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I thought he raced heads up in NMCA??


I race Nostalgia Super Stock, Dcar would not understand. He thinks its Bracket Racing.......

Quote:
Originally Posted by PAUL K View Post
You'd think a class racer would be a little quicker
Getting slow on the off weeks!!!! lol

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  #23  
Old 05-24-2021, 11:26 AM
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I race Nostalgia Super Stock, Dcar would not understand. He thinks its Bracket Racing.......



Getting slow on the off weeks!!!! lol
Lol..... I had no idea bracket racers didn't need good reaction times (insert eye roll here)

I'm sure you would get me ninety percent of the time. You NMCA guys are good. I remember every time Bob Curran or Tony Ortz would enter a local bracket race here, it was all but guaranteed you would see them in at least the semi-finals.

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  #24  
Old 05-26-2021, 01:46 PM
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Seriously doubt any of us could hear noise from a piston only .002" out of spec. The "recommended clearance" of .003-.004 and being at .006 just isn't that critical of difference. Thousandths definitely matter in bearing clearances, but are we are overthinking this on piston clearance when we're talking half the width of a human hair?

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Old 05-26-2021, 05:09 PM
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Originally Posted by lust4speed View Post
Seriously doubt any of us could hear noise from a piston only .002" out of spec. The "recommended clearance" of .003-.004 and being at .006 just isn't that critical of difference. Thousandths definitely matter in bearing clearances, but are we are overthinking this on piston clearance when we're talking half the width of a human hair?
I agree fully with this statement, I've put together engines that were a couple thousandths more piston clearance than the manufacturer called for with no negative results at all.

These were on oval track engines which can tend to run hotter than a drag strip engine, or most street engines. With tight piston to wall clearances you'll be scuffing the skirts of the pistons and transferring metal from the piston in a hotter operating range. The little bit extra clearance is a little insurance in an overheat situation, but in normal operation the extra clearance is negligible. I wouldn't worry about that small amount.

I don't think you'll have any piston slap at startup, but even if you do it's nothing to worry about, my 2005 LS2 GTO (LS engines are notorious for piston slap when cold) has piston slap when cold, and has had since it was almost new. It now has 140,000 miles on it, and no problems, and it's about the same as it was at 20,000 miles when I first started hearing it.

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Old 05-26-2021, 06:42 PM
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I disagree that .002 clearance will not make a difference. There are millions of General Motors cars that would agree with my thoughts.

I'd also bet that .002 clearance going the other way will make a difference and a big expensive mess of things.... JMHO

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Old 05-26-2021, 09:31 PM
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Originally Posted by PAUL K View Post
I disagree that .002 clearance will not make a difference. There are millions of General Motors cars that would agree with my thoughts.

I'd also bet that .002 clearance going the other way will make a difference and a big expensive mess of things.... JMHO
In the case of the OP's situation, the extra clearance shouldn't amount to more than a light "rumble" when the engine is cold. But I agree with you on the modern engines, especially Honda. They spec. ZERO piston to wall clearance as OK on many of the new 4-cylinder engines as a minimum. The piston skirt coating begins to wear off on start-up and creates the "optimum" piston to wall clearance according to their service info. Man, that's tight tolerance.

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  #28  
Old 05-26-2021, 11:35 PM
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Have the skirts coated with a poly moly coating and while your at it have the domes done in a reflective like gold coat you’ll end up with a better engine and in spec .

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  #29  
Old 05-27-2021, 05:58 AM
Dragncar Dragncar is offline
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Quote:
Originally Posted by mgarblik View Post
In the case of the OP's situation, the extra clearance shouldn't amount to more than a light "rumble" when the engine is cold. But I agree with you on the modern engines, especially Honda. They spec. ZERO piston to wall clearance as OK on many of the new 4-cylinder engines as a minimum. The piston skirt coating begins to wear off on start-up and creates the "optimum" piston to wall clearance according to their service info. Man, that's tight tolerance.
I wonder if that coating on the new Honda's is the same as Line2Lines coating ?
That is how their coating works. Fit in while running.

  #30  
Old 06-03-2021, 10:07 AM
brjgto brjgto is offline
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Try Lin2Line coating on the pistons. It is a spray on liner that reduces clearances and only wears to a good running fit. This is highly recommended by my performance engine builder. My engine is going in the car this week after a total blue print rebuild.

  #31  
Old 06-03-2021, 01:40 PM
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There is an old piston repair procedure called "KNURLING". The tool can be set to give the extra diameter you want. Check with the most ancient machine shops in your area.

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  #32  
Old 06-03-2021, 05:29 PM
hurryinhoosier62 hurryinhoosier62 is offline
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Ken, good answer but there very few machinists who know how to correctly knurl a piston these days. Most would just fracture the piston skirts.

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  #33  
Old 06-03-2021, 09:54 PM
Dragncar Dragncar is offline
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Only guy I ever knew who knurled a Pontiac piston blew a rod out the bottom of the pan so hard it dented the frame. Knurling pistons and valve guides was something done back when I was a kid when a customer did not have much cash. Or if there were parts availability issues.

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