[Steve Barcak]

Such a catastrophic failure is very uncommon and needs to be studied. I've hurt a LOT of Pontiacs in my years but, never broke a cam in 3 peices.
How much oil was in the motor? Study this teardown carefully. Something is very wrong for this to happen just chugging down the hiway. Are you sure you were not running it hard? how much rpm? etc.


From the pics I could not see much block damage but it the cam is broke it is probably too far gone. Otherwise, you could sleeve it and save it.
Here is your pic of your head. I circled some things.

First, what is that foil looking thing near where the push rods go?

Second, I circled the area where you and all others would be wise to drill a cooling hole at. Use the gasket as a template and it already has the hole there. Also add the hole in the deck of the block too. You need to practice because the bits tend to stick and break at the end. Do it slowly using oil and good quality drill bits. Use a center punch to start and practice on the junk block.
It will help cooling in this hot area between the 2 exhaust valves.

Hosting-
12th annual Pontiac Heaven March 26-28 Phoenix

[andyg]

That chunk of metal was the biggest piece of piston I could fine. It was stuck where the valve head used to be. I know I should have forged parts but all I could afford when I got this engine was a used original running engine to get the car moving.

["QUICK-SILVER"]

I'm going to guess and say that you'll find another rod has come lose and caused all the carnage you're seeing now, especially with the cam being broke.

And just looking at the beating the head took, you're exhaust is WAY too loud to have not heard anything. In a vert with the top down, wind roar could've muffled it a bit.

[Ben M.]

I'm with Steve and the others. I've never seen such drastic failure like that so quickly. I would venture a guess that your exhaust may not be too loud, but if you were doing 3500RPM on the highway with the windows down it can be pretty loud. If a rod were to let go or valve were to just drop at high RPM, I can see the damage being quite catastrophic very quickly. I don't think a leak in the radiator\timing cover to block or head gasket would cause such drastic failure so quickly though. Likewise, if it was something that was happening over time (failing bearing) it may be difficult to have heard ("rod knocks" are often not very loud until right before they go) to someone who wasn't expecting it.

[andyg]

Top down, loud exhaust, and my trans that is grinding itself to death may have kept me from hearing the problem before it became this bad. Well there's nothing I can do about that now so I made a plan yesterday.

I search craigslist and found a 400 for sale that was running and driving in a car. I went and looked at it this morning and it was a 1976 2 barrel 400 out of a Catilina. It fired up and ran smoothly so I decided to buy it for $350. I'm going to clean it up tomorrow and put it in with the muncie that I was originally planning to swap in this weekend.

I know that everyone here would tear the engine down and get it machined with the good parts so I don't ever have a similar failure, but I can't afford to build an engine that would cost as much as I make in a year only working part time. I'm just hoping to be able to drive the car, I don't need it to be fast.

[johnta1]

The only thing I would do is put a 4 bbl intake on it.

Did your other engine have a 4 bbl on it?

[andyg]

Originally Posted by johnta1

The only thing I would do is put a 4 bbl intake on it.

Did your other engine have a 4 bbl on it?

That's the plan. I have an edlebrock with a qjet on the old one, but I also talked the seller of the engine into "giving" me an oem 4bbl today because I've read here many times that the factory one is better than the low line edlebrock. I also don't like the look of the edle either. It was his discount because I had to help him pull the engine.

[mechanickeith]

I was going to comment that if you were going to re-use the same intake on the new engine, be sure you clean out the manifold. I have seen bits & pieces of rings & pistons get sucked up into the manifold & cross cantaminate parts into other cylinders. That said, the price is pretty good for a complete running 400 motor. Make sure everything is clean before assembly. Make sure no old gasket material/dirt/debri gets in the mew motor. Go slow & double check everything & it will be fine.

[andyg]

Originally Posted by mechanickeith

I have seen bits & pieces of rings & pistons get sucked up into the manifold & cross cantaminate parts into other cylinders.

Funny that you should say that. I had no idea at all how all the cylinders on the other bank had little bits of piston material in them when the pistons and rings were fine on that side. It would have been bad if you hadn't mentioned that and I wasn't going to use a different intake.....

[wrenchmen]

Can you post pics of the valve?

I would like to see where the valve broke.

I second Steves cooling mod, adding the coolant holes in the heads and deck. I had excellant results.

Sorry to see your engine is destroyed.

[andyg]

Originally Posted by wrenchmen

Can you post pics of the valve?

I would like to see where the valve broke.

I second Steves cooling mod, adding the coolant holes in the heads and deck. I had excellant results.

Sorry to see your engine is destroyed.

I'll get pictures of the broken valve maybe today.

On the other hand I got the car running again on monday. It runs smoothly but I'm not sure how 170hp is going to suit me.

[andyg]

I finally tore the engine apart today. I found that none of the rods had broken, just the camshaft. Anyone know what may have hit the cam to break it into 4 pieces?

But the valve broke right above the head. That's where I'm assuming they are welded together at?

Also should I just throw all the engine pieces away? Or could the crank or block still be good?

[screamingchief]

Originally Posted by andyg

Anyone know what may have hit the cam to break it into 4 pieces?

Well whatever happened,almost certainly the last thing that happened was the cam breaking,as after that,no way the engine runs for even a single moment more.

It can infact run with no piston in that one hole,but snap the cam and it's dead.

What did the valvetrain pieces look like,where were they found?

I seriously doubt the piston 2 valve collision caused the cam breakage,the pushrod would have twisted like a pretzel before that happened,that or the rocker arm or rocker arm stud would have broken.

So,IMHO,the cam broke for some yet unknown reason @ this point,like maybe a lifter somehow got out of it's bore and got wedged between the cam & the block somewhere.

But we need more intel on the valvetrain to deduce what the chain of events might have been,nothing is too superficial in this sorta deal.

We need to see ALL the debris,all the tiny bits and pieces.

Often the smallest pieces give the biggest clues.



BP.

[Murf'sDad]

Originally Posted by screamingchief

Well whatever happened,almost certainly the last thing that happened was the cam breaking,as after that,no way the engine runs for even a single moment more.

It can infact run with no piston in that one hole,but snap the cam and it's dead.

What did the valvetrain pieces look like,where were they found?

I seriously doubt the piston 2 valve collision caused the cam breakage,the pushrod would have twisted like a pretzel before that happened,that or the rocker arm or rocker arm stud would have broken.

So,IMHO,the cam broke for some yet unknown reason @ this point,like maybe a lifter somehow got out of it's bore and got wedged between the cam & the block somewhere.

But we need more intel on the valvetrain to deduce what the chain of events might have been,nothing is too superficial in this sorta deal.

We need to see ALL the debris,all the tiny bits and pieces.

Often the smallest pieces give the biggest clues.



BP.

You're secretly Gil Grissom, aren't you? Or wanna be?

Stewart

[screamingchief]

I dunno,maybe?

But I sure do enjoy trying to figure these sorta things out.

And I REALLY like to check out engine carnage pics.

It's just too bad that they all too often come at someone else's expense and frustration.

[andyg]

Originally Posted by screamingchief

What did the valvetrain pieces look like,where were they found?

I seriously doubt the piston 2 valve collision caused the cam breakage,the pushrod would have twisted like a pretzel before that happened,that or the rocker arm or rocker arm stud would have broken.

So,IMHO,the cam broke for some yet unknown reason @ this point,like maybe a lifter somehow got out of it's bore and got wedged between the cam & the block somewhere.

But we need more intel on the valvetrain to deduce what the chain of events might have been,nothing is too superficial in this sorta deal.

We need to see ALL the debris,all the tiny bits and pieces.

Often the smallest pieces give the biggest clues.



BP.

I'm not sure if more pics could help as all the pieces are close to finely ground gravel but I can get more pics tomorrow maybe since you like them so much

You are probably right about the lifters breaking the cam.. The piece that fell into the crank, 2 of the lifters would up in the pan. Other lifters were damaged, physically broken, not wiped. Only 1 pushrod was bent and it came from the broken valve. Maybe the valve hit the piston to break it and that bent the rod?

Again, does anyone think the block or crank are any good? If not they are going to the scrap metal guy tomorrow night. He would love to have a few hundred pounds of metal from one house...

[Murf'sDad]

Originally Posted by screamingchief

It's just too bad that they all too often come at someone else's expense and frustration.

I thought "too bad" was when it happened to you. Isn't that what people say? Oh, wait, that's what you did. Sorry, my bad!

Stewart

[screamingchief]

Yeah,I dont care that much when I break my own stuff,not as long as I get the fun of doing so!!!

I expect to break stuff,I'm pretty hard on my cars by most standards.

Only time I dont like breaking my own stuff is when I break down somewhere unintentionally,and that turns into a major nightmare,but usually it just means a tow home,which is NBD to me.

[Thomasmoto]

When you guys say to re torque the head bolts do you loosen them first or just see if they will tighten back-up to the wrench setting? I've redone mine several times and not loosened them and they seem to all be at the spec ed setting. As in the wrench just clicks at 100. None of the bolts have moved at all. Should I loosen them and come back-up in increments?

[chuckies76ta]

Originally Posted by Thomasmoto

When you guys say to re torque the head bolts do you loosen them first or just see if they will tighten back-up to the wrench setting? I've redone mine several times and not loosened them and they seem to all be at the spec ed setting. As in the wrench just clicks at 100. None of the bolts have moved at all. Should I loosen them and come back-up in increments?

I'm interested in this explanation also..

Charles