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-   -   Pinch too TIGHT! (https://www.rctech.net/forum/onroad-nitro-engine-zone/201595-pinch-too-tight.html)

rcfoolz 01-19-2008 05:25 AM

Pinch too TIGHT!
 
I have a piston and sleeve that is so tight that even after running in 3/4 a gallon, is so tight that I have to take the engine apart to get it unstuck. Any Ideas? Idle temps for running in has been from 170 to 205.....

The piston keeps getting stuck and when I remove it, it has a sticky film on the sides of the piston, and to get it to start up again, I have to clean the film off the sides of the piston....I've done this 3 times and I'm about to toss it to the side.

thanks

Roelof 01-19-2008 07:18 AM

Pre-heat the engine with a hairdryer for less pinch....

About the film... what fuel are you using? Maybe worth a try to use another brand fuel?

rcfoolz 01-19-2008 07:37 AM

when I use a heat gun, the engine is still to tight to get unstuck after I shut it down. I've tried Sidewinder, RocketScience, and Werks fuel, it doesn't make a difference, it just gets this sticky film on it.

I was thinking about taking the sleeve out and heating it with the heat gun and pushing the piston to the top and letting it cool. after that I would have to heat it again to get it out, but I though maybe it would resize it just a bit....any thoughts on that?

TomB 01-19-2008 08:05 AM

dude man, pritty obvious, if it's this tight, put more headshims man;)

cdelong 01-19-2008 09:36 AM

run it up to 220- 225F. Does not sound like your fuel is good with that film.

CKmaxx 01-19-2008 03:15 PM


Originally Posted by TomB (Post 4093937)
dude man, pritty obvious, if it's this tight, put more headshims man;)

Your kidding, right?

cdelong 01-19-2008 05:05 PM

it lowers the compression and does not abuse the rod as much. I always add a tenth or two for break in.

TomB 01-20-2008 02:09 AM


Originally Posted by CKmaxx (Post 4094834)
Your kidding, right?

no i'm not. if this does not fix it, then it's possible that the piston and sleeve is a very bad match, and something went terribly wrong when it was assembled in the factory. might be one of those 1 in 5000 type scenarios.

joe_jenkins 01-20-2008 02:26 AM


Originally Posted by TomB (Post 4096156)
no i'm not. if this does not fix it, then it's possible that the piston and sleeve is a very bad match, and something went terribly wrong when it was assembled in the factory. might be one of those 1 in 5000 type scenarios.

such as my murnand modified 35 plus 31 that god broke in half at the block
http://i178.photobucket.com/albums/w...ndcrash-51.jpg

joe_jenkins 01-20-2008 02:27 AM

i was getting off our second straight and then doin a 180 then going into the S curves when a guy in front of me hit a pipe and went under the pipe and i hit him and his bumper hit the head of my car and ripped it backwards

rcfoolz 01-20-2008 02:07 PM

I've had the discusion with a fellow racer that siad the same thing about the fuel....I'm going to be running another brand fuel through it after the Chargers/Paitriots game......I'll run 3 tanks in it to test the theory and tear it down and check the pinch/film build up.

MHarrison 01-20-2008 03:52 PM

:nod:

rcfoolz 01-20-2008 05:06 PM

still very tight, but no film build up this time......:D

JFCJ 01-20-2008 05:14 PM

rcfoolz,

what are you using for afterrun oil?

J

rcfoolz 01-20-2008 05:19 PM

I hadn't used any in that engine with the brand new piston and sleeve......It has 7 tanks in it, I was using sidewinder for the first 4 tanks, and then I ran 3 tanks of RocketScience. I couldn't realy tell you true temps due to the ambiant air is cooler then it was with the other fuel.


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