Well... You probably remember me. I posted last week about an engine I blew with only 30 miles on it. Well I pulled it and this is what I found.

 

Here is a piston. Two of them looked like this.

 

Here is the block.

 

Here is what was in the oil pan.

 

looks like you bent a rod (hehe)!
was this a crate motor or did you build it?

 

Here is the crank and cam. The red circle shows the gouge in the crank and the yellow circle is the cam. Notice you can see the lifter hole because the cam snapped in half.

 

Here is what I think happened. The red circle shows that the rod bolt is missing. I found it in the oil pan. I think it just broke.

 

damn that hurts to look at. there's a little less to reuse than you had originally hoped when you posted your other thread.

 

Now to start the new engine. I have all of the parts. Just need to assemble. I totaled up all of the recipts and I spent $2760 on the "old" engine and the only things I could save off of it was the waterpump, carb, intake, and I think the rockers are ok. A grand total of about $550. The pistons smacked the heads and broke\bent valves, So now I need to get the heads redone again. I spent another $2200 on the new parts...keep in mind the "old" parts only had 30 miles on them. All indications point to that I over reved it put I know I didn't. I was so careful with this engine. I don't know how the pistons smacked the heads. Just thought some people might enjoy looking at these pics. I know I do.

 

WOW what were u reving at 10,000.

 

in the great words of Animal from the Muppet Babies cartoons....."NNNNNNNNNNNNNNNGOOOOOOOOOOOOOOOOOOO BYE-BYE!!!!!"
that engine got fubared!

 

Believe it or not it was only about 2000. And Im not kidding. It was sitting in the driveway and It had only been started for about 30 seconds. I reved it up to about 2000 because it was dying due to the choke not being set, abd then I heard the dreaded "POP".

 

After your last build, I believe I'd pay a pro to do this one.

I don't mean to rub your face in it (too much) but you appear not to have the engine assembly thing figured out.

 

Um...actually I assembled it just fine. And besides, you don't learn any thing from having other people do it for you.

 

so long as the guy assembled it carefully with a shop manual, torqued it all coreectly, checked all clearances and what not i'd say it wasn't his fault. heck i was barely 18 when i did my first motor and i assembled it with only the help of a Haynes manual for 82-92 firebird with no priar engine building experience. cleanliness, attention to details and GOOD PARTS are the key factors to the longevity of a motor. skimp out on one of those 3 key areas and you can kiss it good-bye

 

I followed the haynes manual for rebuilding a sbc and I had everything machined. I even used plastiguage. Followed every torque setting. I honestly think that it was the broken rod bolt. I mean...It was my fault for not buying new rods. I just had the old ones reconditioned.

 

doesn't sound like it was anything on your part that caused the motor to grenade. i used recon'd stock rods on my first motor and that thing practically lived at 6500rpm and it lasted 2 years before my buddy stripped out the crank snout after a cam swap trying to reinstall the balancer by pulling it on with the crank bolt thats when took the opportunity to sell off the parts and start my 383 (*hint* *hint* *build a stroker!*) lol

if it is any consulation.......i have seen more motors than i care to mention built by the "best" speed shop in the area completely detroy themselves due to their half-a$$ed approach to building motors. one example: my buddy's 406 in his s-10. they built the motor and said they dynoed it @ 540hp. well he picked it up from them, took it home and put it in his truck. he spent a 3 day weekend installing it and doing all the wiring and fule plumbing and what not. he gets in the truck and turns the key, the fuel pump comes on and he pumps the gas a couple times........turns the motor over......half a revolution and BLAMMO!!!!!!! well he tears down the motor and finds that they installed his gear drive about 5 teeth off with a .6xx solid lifter cam and it bent every valve and gouged every piston when they smacked. he takes it back to them and they were like "we can't do anything for you because you took it apart....it coulda been something you did to the motor. if you woulda brought it back to us right away we might have been able to do something about it" well there was $5000+ that he coulda just wiped his butt with. like i said.....those 3 points are critical to a motor's like.....sounds like to me you had a faulty rod bolt which you really had no way of knowing about.

 

If it wasn't for the money issue Id be all over the stroker like a fat kid on a cupcake. Im just glad I didn't have $5000 in it like your friend. But I learned from my mistake and bought new rods.

 

sounds like a good plan. might want to consider putting arp bolts in them if they don'r have them already. one thing i learned early and listened to was spare no expense on the bottom end.

 

If it wansn't for people on this forum I probably would have paid someone to build it for me, but they convinced me that I shouldn't. Its very satisfying to be able to say you built an engine yourself. Plus it was cheaper to do myself.

 

Something doesent look right. Notice the 30 over (as marked in pic) flat top pistons then looking at the block it appears to be a standard bord with indications of wear (brown ridge.) These dont add up for a engine with 30 miles on it. My guess is that that engine was not machined correctly, even if some one already borded it over in the past (doubtfull) that ridge should not be there if the block was infact machined. The machine shop didnet do a good job and Id be beating some heads in right this second if I were you!

 

I had a local machine shop do the block. I know it was done, but done correctly?...I don't know. It was a standard bore when I took it in and they did it .030 over. They also put in the freeze plugs, cam bearings, reconditioned the rods, turned the crank, and put the new pistons on the reconditioned rods. I think the ridge you are seeing is just oil and antifreeze. There is no actual ridge. The picture just makes it look that way

 

Reference point. Opinoin only.

 

I understand that, but I know that the block was bored. It had a very nice cross hatch on the cylinder walls, plus I know what it looked like when I took it in there and I know what it looked like when I got it back. Weather it was bored .030 over or not I dont know. But i know it was bored. There is no ridge on the walls. It had one when I took it to the shop but not now. It is as smooth as can be. No lip at all. There is a small chamfer at the very top but I thought that was supposed to be there. If indeed it isn't bored .030 over I should be kicking someone in the *****. I will check the bore tonight.

 

A better picture.

 

I noticed too that if you look at the partial pistin in the above picture, look at the wall clearance. Does that look to big to anyone? I believe it was bored, but how much, I don't know.

 

Must have been using dyno oil in that thing.

 

dheck sorry about the engine, but your right it does feel good to build your own motor and it last, i rebuilt my 305 myself from scratch, i had a machine shop do all the block work/freeze plugs/cam bearings, bored .20 over, reconditioned the rods and installed on new pistons, crank turned .10 under, i bought federal mugel bearings, the expensive nhra approved ones in summit, i put it together and i now have 3500 miles on the motor purring like a kitten and have brought it to 6500 rpms, the one thing i noticed about your block, i dont know if it's anything, but in your coolant passages i see rust..., did they dip/clean the block and magnaflux for cracks? mine was totally clean and painted when i got it back, just a thought, machine work is everything, you may want to check for a different machinist.

 

you dont do anything mall do you? Ive seen some prett godd engine failures seeing as how I work at a dealer but thats a good one. if it werent for all the wasted money there I would be proud of it.

 

Hey...If your going to blow an engine you might as well do it right.

 

You definetly nailed that down!!

 

Good point, but I think that it would have locked up with in the first few minutes of running, not after several startups.

 

Man, your pics make me have second thoughts about going to the track tomorrow night. Ouch.

 

Looks just like it broke a rod bolt. Seen it plenty of times before, including a rather nice 396 my brother built for himself. It is never a pleasant sight.

Pistons don't expand .030". You can't put a .030" over piston in a std bore block. That's BS. Piston-to-bore clearance is about .003-.006" cold, depending on what kind of pistons, intended use, etc.

Don't change your plan, I think you can master this, it's not rocket science or anything. If I can do it, a person with any intelligence at all ought to be able to do it better than I can.

Of course, you see why I said the cam was probably bad... that's usually one of the casualties.

Good luck!!!

 

I'll go along with the rod bolt, too. Most likely you didn't get it torqued properly when you put it together. If you can, post a pic of the two (or however many) pieces of the bolt.

A loose bolt will break before an overtightened bolt, if you can believe that. For insurance next time, after all 8 pistons are in, start at the front and torque all 16 rod bolts - use a check sheet, mark after tightened, count each bolt tightened out loud - anything to make sure there aren't any loose ones.

If you use a stretch gage, this error almost becomes impossible.

Many, many years ago, one of the mags had a project engine they built and installed in a Monte (or something like that). They made a few chassis dyno runs, shut it down, came back after lunch and it blew when they started it up. Disassembly showed the rod bolts were only snugged up, never torqued.

Even the "experts" can screw things up.

I never have, of course...

 

I agree with the broken rod bolt and question wether or not you checked the ring gap clearance. If that particular bore was not honed correctly, and you installed the pistons you would have virtually if any ring gap. It is possible that you didnt check the rod bolt to ensure that the bolt was not pressed in or seated properly on the connecting rod that is easy to oversee since no manuals tell you to check that before torqueing. A loose bolt will break before an over torqued bolt will. Dont beat yourself over the head about it New bolts break right out of the box there is no way of telling when a bolt will go.

 

I just hope everything goes ok the second time around. I am going to buy some arp rod bolts. I really apperciate all of your guys help and input. It is supposed to be nice this weekend so I think I will drop it in. I have heard of something called a catastrophic stop, when something causes the crank to stop abruptly (like a broken rod bolt) and the piston seperates itself from the rod because it is still in the middle of the stroke and the rod comes to a complete stop at 2000 rpm, the piston has no where to go but up and I think thats why my pistons seperated and hit the heads, but I could be wrong. As for torquing down the rod bolts...I checked and double checked but that doesn't mean I still didn't miss one.

 

Thats the first connecting rod I've seen at a 90 degree angle

 

Damn Dude, Im impressed.

 

way to go.

now.... that being said. damn, dude.

like everyone else has said, don't let this discourage you.

make sure everything is clean when you assemble the new engine. torque everything. use a chart like five7 mentioned if need be.

and most important, if you have any questions.... ASK!

 

RB83L69 ,is correct its not that hard and you can do it. The one thing that I have learned is not tp skimp on the bolts whether the are head , rod , header , flexplate or torque coverter bolts. They are too important and too inexpensive to not use the best. Good luck with your next engine .

 

Sorry to hear that man, those were forged rods too. My deepest condolences!

 

those pictures are grusome! did it with style.
good luck on the next one.

 

This just came up in my head, when the first internal combustion engine was built, how did they know how tight the bolts should be?

 

Torque specs aren't specific for a certain part, it's all based on the size of the bolt. A bolt will have the same torque spec whether it's for a head, intake, or even carb. They measured the right amount of pressure to be in the safe zone for that size. Now with that said,

dheck: I must say, I've never seen an engine blow like that. I just tore apart an engine last weekend that overheated and the rod busted in half shattering the piston. It was in a friends truck, it happened on a brand new GM crate engine with less than a 1,000 miles. He didn't have a temp gauge and he put the smallest flex fan on backwords without a shroud. So it too granaded, and I had to supervise the new rebuild so it wouldn't happen again. But, don't let this incedent turn you away from building them. Look at it as experiance and a good story to tell at the local bar. Now you have bragging rights that you blew the sh-t out of a small block.

Last but not least, you have to remember one thing when working on car, sh-t happens. There's always something and the more you work on them, the more you become aware of it.

Good luck with the new one!

 

Well I get my heads today. I bent 3 valves. I hope to assemble the new engine this weekend. I don't know if I will be able to drop it in or not. I really appreciate your support. Hopefully good things will come. You can only have so much bad luck until some good luck rolls around. And I think Im due for some good luck. I will have an update this weekend for all of you. Maybe I can look at this and laugh after this is all over.

 

Hmm. Lets dig a little.
<b>Pistons don't expand .030". You can't put a .030" over piston in a std bore block. That's BS. </b>

Sorry, but my .030 over pistons fit in my Std. size bore. The rings take up most of that extra room, and the rest is taken up by piston expansion.

Remember, forged pistons need more piston-to-wall clearance than cast pistons. If the machine shop bored the block to cast piston- type clearances, you will have a problem under high cylinder pressures...

<b>Good point, but I think that it would have locked up with in the first few minutes of running, not after several startups.</b>

<-opinion>It would take some time to generate the kind of heat and friction to finnaly once and for all seize the piston up.<-/opinion>

<b> I bent 3 valves</b>
Last time I checked you only destroyed 1 rod/piston? How did a totally different piston come loose and bend a valve if it was properly connected to the crankshaft. Did you float the valves right before the engine blew up? Your telling me another piston threw a rod bolt too? at the same time? That doesnt make sense, 3 valves. Somthings not right.
<b>Here is a piston. Two of them looked like this.</b> Do you have a picture of the other piston?

I guess where Im having a problem understanding is if A rod bolt was at fault (as in 1 rod bolt) why did 2 pistons eat it? How come the rod is bent as if the piston seized up and the crank couldnt move it so it bent the rod? Obviouselly (to me anyways) , the crank is what bent that rod. It bent the rod because it was pulling on the piston and the piston wouldnt follow. but the piston is up in the head, which means it hit the head before the piston seized up. How did it hit the head, the bend the rod if the rod bolt is at fault? it would have disconnected (rod bolt) THEN hit the head, and would be bent with a much different because then theres only 1 rod bolt connected and the opposite side of the rod would be opened up like a tin can. I've seen faulty rod bolt/broken rod bolts, but never one that came out and didnt affect the journal somehow. maybe I just cant see it clearly in the picture.

 

The rings don't take up that much room. They don't "take up any room" at all as far as bore clearance is concerned, because bore clearance is measured someplace else on the piston, at the skirts specifically, a couple of inches below the ring lands. Cast pistons usually are desinged with .002"-.003" of bore clearance, forged .005" - .006" typically for a street build. High cylinder pressures have nothing to do with the issues at hand: they don't affect the sizes of metal parts, to the tune of almost 1/32" of an inch (.030").

The reason 2 pistons broke is because the broken rod hit another rod, no doubt the one next to it. The reason the rod is bent is because it was not all the way at the top of the bore at the instant of the failure, so the crank came around and hit it on its next rev. The reason it bent 3 valves is because after the broken rod hit its neighbor and broke the pin out of that piston's pin bore there were 2 pistons flying around in their bores not connected to rods, which then smacked into open valves (or vice-versa). The rod is not bent as if the piston seized, which it obviously didn't, by the near-perfect appearance of both the piston and the bore; the reason the rod is bent is because after the first bolt had broken and was long gone, and then the remaining one finally gave out, the crank hit the rod after they became disconnected from each other.

If you don't know what you're talking about, then please don't post a bunch of garbage, it will only confuse a person who is actually trying to learn something, as compared to someone trying to show everybody how much he knows when he actually is just shooting off his mouth.

 

<b>High cylinder pressures have nothing to do with the issues at hand:</b>

So your telling me that high cylinder pressures wont cause the ring to seize and result in piston seizeure / failure? crap.
I know because it happened to me

Dont tell me I dont know anything. I know what I know and I was only trying to help.

If you Look at how I phrased my questions:
<-opinion>It would take some time to generate the kind of heat and friction to finnaly once and for all seize the piston up.<-/opinion>

Doesnt that mean somthing? Does the word opinion rattle your brain? it means im NOT SURE that Im just SUGGESTING what MIGHT have happend!

LOOK HERE:
<b>I guess where Im having a problem understanding </b>
Doesnt that mean anything? Do the words I GUESS help you understand my point of view? IM TRYING TO LEARN FROM THIS, IM NOT SAYING I KNOW WHAT THE PROBLEM WAS.

Holy crap dude, I never said I was sure of anything. IM JUST TRYING TO HELP. Dont bite my head off because I dont know everything.

Oh and by the way, I used your "So many mustangs, So little time" on my license plate cover... Hope you dont mind.