Gen1 SBC tear down help

[YZF]

I pulled the engine out of my dad's car to reseal the entire engine. It was leaking oil really bad from the front seal so out came the damned thing. Got it tore down to the heads. Go to pop the heads off and this is what I see underneath. I need to know what happened here and what I need to do about it, or if its ok to run on. Im not an engineer, nor am I an engine builder so help me out here.

http://i41.tinypic.com/30ndlja.jpg
http://i43.tinypic.com/2rf3kzn.jpg
http://i43.tinypic.com/2ahxjbs.jpg
http://i43.tinypic.com/2edzk37.jpg

And a shot of the combustion chamber for that cylinder.
http://i42.tinypic.com/t6w9ja.jpg


Was this running way lean? The motor sits quite a bit. It actually sat for about 3 years but I recently had it running this past summer only to see how bad the oil leaks were and where they were coming from.

Give me any input you may have about this!

[AChotrod]

Looks like a broken piston to me and could use a rebuild while its out. Did you find the rest of it? If the cylinders look good just hone them and put a new piston in. Looks pretty good in the pics. The leaks could of been causing it to run lean.

[joelster]

That is a broken ring land. That is not good. I can't believe that there is no other damage. Somehow, that chunk of piston made it out of the motor without sticking a valve open and causing the piston to come up and smack it. This might sound crazy but, pop the head back on and do a compression check on that cylinder. It is starting to gouge the cylinder walls. It has been this way for a while too if you look at the ridge pattern at the top of the cylinder.

What is this motor out of?
Is it a dd vehicle?
Does he plan to keep it?

BTW, the combustion chambers look excellent and so do the tops of the pistons, not that i'm an expert or anything, but they look like there is ZERO sludge anywhere.

[YZF]

Its a 406 (punched over 400? we dont really know). He would like to get it running to get it out to the track. It runs pretty good for what it is. Its definitely just a weekend car when it DOES run. The guy he bought the car from (in sep of 1997) said it had a "fresh" motor. And its been maybe 20k miles since then. It was a DD for about 6 months back in 2003 but the LF wheel bearing went out and its kinda fallen apart since then :(

In the intake valley, it looks practically brand new. Which is awesome

[KissMyWhtSS]

I'd get the block honed and new pistons/rings. Everything else looks fine thus far.

[jakesz28]

It could have been a bad piston or it could have been caused by too much fuel and timing. If the carb runs rich the extra fuel ends up in the ring lands and over time the extra heat that that creates will break the land.

[YZF]

It could have been a bad piston or it could have been caused by too much fuel and timing. If the carb runs rich the extra fuel ends up in the ring lands and over time the extra heat that that creates will break the land.


This is an explaination I was waiting for! Something logical as to why it might of snapped.

If it needs a rebuild, its going to have to wait. Its just not a good time to be spending money on a rebuild right now.

[joelster]

Its a 406 (punched over 400? we dont really know). He would like to get it running to get it out to the track. It runs pretty good for what it is. Its definitely just a weekend car when it DOES run. The guy he bought the car from (in sep of 1997) said it had a "fresh" motor. And its been maybe 20k miles since then. It was a DD for about 6 months back in 2003 but the LF wheel bearing went out and its kinda fallen apart since then :(

In the intake valley, it looks practically brand new. Which is awesome

Those pistons look 100% stock. Usually they will be stamped .030 on the top. Maybe it's just covered with a tiny layer of carbon. Why would anyone put generic straight plug 1.94/1.5 heads on a 406?

Did they guy before your dad ever spray it? That would explain the ring land better.

[YZF]

I doubt it was sprayed. No signs of any lines, wiring, mounting points, etc. Weve been inside and out of this car and never noticed anything like that.

The only known fact about the motor is that its got a lumpy cam in it. Its very audible. Beyond that, we have no idea on the actual status of the internals besides what the guy told us.

[AChotrod]

Did you find the chunk?

[joelster]

Did you find the chunk?
That is out on the road somewhere or rattling around inside of the muffler, guaranteed.

[YZF]

That is out on the road somewhere or rattling around inside of the muffler, guaranteed.


Muffler? LOL

Old school Glasspacks at the end of some straight pipes.

And nope, there was no chunk in said engine.

[joelster]

It's stuck in some dudes tire, which caused him to lose control of his car, lol.

[YZF]

It's stuck in some dudes tire, which caused him to lose control of his car, lol.


Ah, it all makes sense now! He got rear ended by an 01-ish cougar awhile back. Totalled the cougar, had to get a new bumper and tips on the Nova haha.