PDA

View Full Version : 4D55 piston protrusion



Maxedoubt
12-31-2015, 02:33 AM
Hi guys (& gals?)- Been "out of the loop" for awhile, but now I'm crawling back for guidance:
I've just partially completed a 4D55 block rebuild using ITM .020" pistons. Installed #2 and 3 piston/rod assemblies, and it looks like crown protrusion is running about .065". YIKES! Is that TOO MUCH? Can't seem to find the correct specs anywhere.

mikewarme
12-31-2015, 08:46 PM
I will look into it for you but I NEVER had a good set of ITM pistons as all once running made clanking sounds from valves touching piston. No not enough to lock up but enough to make a knock and cause you to dremel the pistons where the valves sink in.

Maxedoubt
01-01-2016, 05:21 PM
I will look into it for you but I NEVER had a good set of ITM pistons as all once running made clanking sounds from valves touching piston. No not enough to lock up but enough to make a knock and cause you to dremel the pistons where the valves sink in.

HMMMM... Did you have this same issue with more than one set of these? I wonder if maybe the pin bore is machined a little too low, causing the piston to ride higher.

mikewarme
01-01-2016, 06:53 PM
With maybe 5-6 sets. There answer to the problem was to discontinue making them. Bunch of assholes with their taiwan crap

Maxedoubt
03-09-2016, 02:00 PM
ANYBODY.....piston protrusion........anybody........?