!@#$%^&*" Look at this and give me your opinion

[Zack]

Ok, got the Cobra engine back out of my Marauder (this is the old engine that came in my Cobra)

I had to remove it because the #8 bearing I THOUGHT was the problem really wasnt. After a much more thorough analysis I realized the noise was coming from #2 hole.

As I removed the heads, I noticed the bolts were the loosest of any mod motor I ever disassembled.....dont know if it affected anything though.

Got # 2 out and found this.

I was like.....

I ran my finger nail inside the cylinder and it is still smooth.
If I get the correct measuring tools and to a quick hone, do you think I can get away with replacing the piston? (I have about 12 good pistons laying around, lol)

BTW the rod bearing is PERFECT and no binding of the piston on the pin.
I will remove all pistons and inspect everything, I just had enough for tonight.
Also, the top of the piston and combustion chamber are beautiful....no signs of detonation whatsoever.

Opinions wanted, and thanks.

Click to read more...

 

[01bluesnake]

Its looks as though the piston got a little too much heat in it. Ill have to look at a few of my bad 03/04 pistons that i know got melted down from running lean on the driver bank, but want to say looks about the same. As fas as the wall goes, try hitting it with a quick ball hone and see if any lines are still present, but if your finger nail isnt really grabbing, i would say thats a good sign.

 

[Zack]

Thanks ^^^^

Another thing to mention: when I remved the 2 rod bolts, one of them came out with the threads all goobered up.
Whomever assembled this engine was a toolbag.

 

[01bluesnake]

lol, another reason im assembling mine. Snaped some pics of mine, but no heavy side wear like yours.

 

[Zack]

If all the other cylinders look good, I will buy a ball hone, measure then re-evaluate.

 

[01Cobra]

Fucking Cobra motors.

 

[01bluesnake]

Heres a few of my pistons for comparison, ran a little lean and lots o heat.

 

[Zack]

Fucking Cobra motors.

Makes me want to build up that 390 I found, throw it in with a nice cam and carburetor. :alcoholic

 

[Aron]

What all was done to the block? The way all the damage is on one side of the piston, the cylinder may be out of round. I would have the holes checked for roundness, especially since you said the head bolts were loose. That in itself could make the cylinders out of round. That's why they bore and hone with a plate bolted to the deck, to simulate the head bolts shifting the cylinder when a head is installed. Otherwise, if they didnt use the plate when you torque the heads down, you will pull the cylider out of round

 

[01bluesnake]

Also, were the head bolts factory torque to yield or ARP's? May of "lifted" the head ever so little from the pressure with the factory's giving them a more than loose feeling. If they were ARP's, my guess would be not torqued evenly

 

[Zack]

This is the first time this engine has been opened up. They are TTY Bolts.

The bolts were not loose loose, just way less effort to remove them than Im used to.

 

[01bluesnake]

ya lol, didnt mean loose but less removal torque. With the boost and timing, the pressures in the motor have to be pretty high, only other thing i could think of unless they werent correctly torqued initially.

 

[Aron]

Oh ok. I can never keep your engine projects straight. I thought that one was repaired

 

[Zack]

I can get a brand new Forged Shortblock for $2600 with 5cc pistons.

Wondering if this is the smartest thing to do, then sell off the remnants of this Cobra engine.

This particular shortblock uses Mahle pistons, wondering if they are better than the Mahle's used in the Cobra engine.

 

[SC Cheesehead]

This outta the Black or the Blue?

 

[Zack]

This is what a torn down modular engine looks like, lol

After some more investigating, it appears as though #7 piston suffered a similar, but not as extreme fate.

Im torn at this point. Do I replace the 2 bad pistons, or open the wallet for some machine work and Diamond pistons?
Blah....:argue:

 

[DEEZUZ]

love hot combustion chambers.....

 

[Zack]

Slept on it....decided id be a fool to replace 2 pistons.
Gonna have it machined, Coated Diamond slugs and i will assemble it when its done.
I will also have the heads refreshed so this engine should outlast the car.

 

[rz79]

God I wish I had your money.. You sir are my DIY hero.

 

[Zack]

God I wish I had your money.. You sir are my DIY hero.

LOL its credit my friend.

I have about 3-4 projects lined up over the winter that will pay all these bills.