Sportruk

I'm looking for some help from you experienced engine guys.
I had to pull the 408 due to a leaky rear main seal and a couple other leaks. It has been running perfect and I hated to pull it, but I was not going to try to replace the 2 piece rear seal under the truck again.
I have a slight wear spot on all the cylinders which I thought was odd. It's not major, as it has just barely removed the crosshatching.


This is on what I would have thought would be the unloaded side of the cylinder. The pic below shows the piston starting down on the power stroke. I would figure the force against the rod would drive the piston to the left side, but the wear mark is on the right side. There is virtually no marks on the piston.


The other issue I have is the rod bearings. The rod side of the bearing is showing some copper. I have only pull #6 piston so far, but I would imagine they all look like this. I need to get some Plastigage to check the clearance, but I was thinking of just rotating the bearings 180* if the clearance is OK or do you feel there is something wrong here. The bearings are Clevite 77.


The engine has about 6000 miles on it. I run 20W50 Quacker State dino oil. The builder said I should run the 20W50.

lightningguru26

jees! Ford diesel's only run 15w40 or 10w40 in the winter, i would say that a little thick. i would say 5w30 would be good for you.

redlightningssf

Thats what my 427 stroker looked like BUT two pistons had chunks missing off the top of the piston.The walls of your cylinders are not that bad, what does the piston look like. I chose to not go stroker again because my motor had less miles and more scratches on the pistons.

Sportruk

The piston looks like new, other than some carbon buildup on top. Minimal scuffing on the skirts.

giddyup

eek....my 187k mile stock shortblock didn t look that bad.

badpony93

if the bearing is only worn through on the one side and the cylinder on one side, I'm thinking the rod might be bent or the wrist pin is no bueno, something's not right

thePUNISHER

id say that was from skirt contact. mayube too much piston to cylinder wall clearance....

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billheis

I do believe thepunisher is right, there's some piston rocking going on there. As far as the bearings, have you had any detonation? Are you using a 6.2 rod? or shorter? It looks to placing quite a load on it. Mike the crank and put rod cap back on the rod and mike the inside of the rod separately. Don't use plastic gage to check at this point.
Bill

thePUNISHER

to my knowledge the 408 isnt the best stroker to be puttin mileage on....

__________________
Paul's ClutchBoxes......performance built E4ODs and 4R100s.... street and COMP valve bodies.

lightning2fast@aol.com

bones93

it could also be to tight for the forged pistons.

Sportruk

The worst part of the wear mark is between 1.5"-2.5" from the deck. The skirt is 2.5", so I don't think the skirt did the mark. The light part of the mark starts at 2.5" and travels to the very bottom, so I would say that is caused by the skirt.
The second ring has an undercut bottom side and it is very sharp. I think the piston is rocking slightly and the ring has scraped the cylinder.
I don't have micrometers, but using plastic setup shim material, I could slide a .003" shim in with the piston and the shim could be pulled out, but with a .004", it was very tight. This was at the bottom edge of the skirt.
I tried the plastigage yesterday and it's showing .001" clearance on the rod bearing.
The only measuring device I have is a digital caliper and I have no way to verify the inside and outside measurements against itself.
The rods are 6.2" Eagle forged I-beams. A complete Eagle rolling assembly was installed.

bones93

In my opinion i wouldnt ever use plastic gauge its not accurate enough. i would take the rods/pistons and block and have them measure with the proper tools. Are you running a nepier second ring? because thats what it sounds like by your description.also dont forget that your piston to cylinder wall clearances are going to be different with a torque plate or cylinder on. do you got pics of the pistons and rings?

Sportruk

This is the side that caused the marks.

billheis

I see the problem, A&W, it should be Mountain Dew. Just ask Ed. lol
No just kidding. It almost looks like its tight. Yeah as bones93 said, take it to the machine shop and have them measure it. Back when, when I use to build engines as part of my job,the boss wouldn't let us use plastigage. I still have most of my stuff, but I'm in FL and you're up there where its cold. Take it all apart and have everything checked.
Bill

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94 Red Lightning #3802 made on 06/01/1994

Bad as L

Can you pull all the main caps and take pics of the parting lines ??