FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#21
|
||||
|
||||
Quote:
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. |
#22
|
||||
|
||||
I race Nostalgia Super Stock, Dcar would not understand. He thinks its Bracket Racing....... Getting slow on the off weeks!!!! lol
__________________
66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 Last edited by Mike Davis; 05-21-2021 at 05:27 PM. |
#23
|
||||
|
||||
Quote:
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. |
#24
|
||||
|
||||
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?
__________________
Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
The Following User Says Thank You to lust4speed For This Useful Post: | ||
#25
|
||||
|
||||
Quote:
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. |
The Following User Says Thank You to Sirrotica For This Useful Post: | ||
#26
|
||||
|
||||
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 |
#27
|
|||
|
|||
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.
|
The Following User Says Thank You to mgarblik For This Useful Post: | ||
#28
|
||||
|
||||
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 .
__________________
Happiness is just a turbocharger away! 960 HP @ 11 psi, 9.70 at 146. Iron heads, iron stock 2 bolt block , stock crank, 9 years haven't even changed a spark plug! selling turbos and turbo related parts since 2005! |
#29
|
|||
|
|||
Quote:
That is how their coating works. Fit in while running. |
#30
|
|||
|
|||
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
|
|||
|
|||
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.
__________________
GOOD IDEAS ARE OFTEN FOUND ABANDONED IN THE DUST OF PROCRASTINATION |
The Following User Says Thank You to KEN CROCIE For This Useful Post: | ||
#32
|
|||
|
|||
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.
__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#33
|
|||
|
|||
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.
|
Reply |
Thread Tools | |
Display Modes | |
|
|