new to the nitro scene(1/8 buggy)what do they mean by needing a pinch any info would be helpful thanks

Thats a piston/sleeve resizing!! You do that when the compresion of your engine is low. After pinching you are good to go a few gallons!!(1-2)....Thats all i know!

Pinching is an attempt to resize the sleeve to re-establish the tight fit between the p&s at the top of the stroke. Pinching is not intended to resurect the dead; but to extend the life of the engine. So, the advise is to do mild pinchs throughout the engine's life. How often? you'd get a different answer from each driver.

Though You will find a great number of drivers who will sware by pinching... I do not subscribe to the practice.

I believe the sleeve is no longer round. It may feel tight at top of stroke but the seal between p&s has been comprimized. Its possible to compress brass but the chrome lining is not a malable material.

Pinch is the force you feel when you turn the crank around without glowplug mounted. These engines have no pistonring and the solution is a conical shaped sleeve with a slight oversized piston you have to run in zo they will shape to each other perfectly on the right temperature.
In cold conditions with most enginen some pinch is a good sign because on temperature the pinch is gone due the unequal expansion of the piston and sleeve.

Pinching is a methode to make the upper part of the sleeve smaller using a press arround the sleeve. This is only needed when the set is loosing compression.

thanks all for the info-bugsee2

I had an HPI G3.0 engine repinched. It was almost as tight as new, and had a much better seal, but I sold the truck before I ever got to run it.