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SB400 carnage pics
- Thread starter mountainexplorer
- Start date
mountainexplorer
1/2 ton status
And more pics:
Think I could JB weld this back into the cylinder wall?
Think I could JB weld this back into the cylinder wall?
85mudblazin
1/2 ton status
Wheres the story?? 
How?
Shaggy
3/4 ton status
Yow, I bet that sounded ugly when it let go!
mountainexplorer
1/2 ton status
Did I mention this motor has less than 2000 miles and made no noise up until it all happened at once? 5 seconds tops from noise to shut down at under 2000 RPM when it occured and it was over. Here's what the motor was like.
http://coloradok5.com/forums/showthread.php?t=110381
Here's the "what"/how:
http://coloradok5.com/forums/showthread.php?t=130515&highlight=Detonation
http://coloradok5.com/forums/showthread.php?t=110381
Here's the "what"/how:
http://coloradok5.com/forums/showthread.php?t=130515&highlight=Detonation
mountainexplorer
1/2 ton status
It sounded like someone dropped a bunch of bolts into the motor all of a sudden, and about 4 seconds after that it shut itself off. That was it. No exaggerations. It was done and over with before I could push the clutch pedal down all the way.
Silver84k5
1/2 ton status
and that was all from detonation?
you did a number on that thing man
you did a number on that thing man
Autopsy results--CSI for DOA 400
A moment of silence for our fallen 400 small block--another of chevys rather rare and best motors passes into oblivion--R.I.P.
Not making fun of your misfortune--I hate it when a chevy motor blows up,and its frustrating to not know what caused it--after a catostrophic failure like this its kinda hard to pin down the exact cause...so many parts get wiped out in a few seconds at 2000+rpm its nearly impossible to say which failed first and started the chain reaction that finished it off...
How many peices was the camshaft in??--I saw a new chevy citation years ago that spit a 3 inch section of the cam ,with 2 lobes,out the side of the block.and it actually kept running long enough for the owner to bring it to the dealership my brother worked at--it blew up and seized as they were driving it into the service area --the lifters must not have fell in after the cam broke right away,but at least one fell in during the trip to the service bay,and that was its last revolution!--Your cam might have snapped in 2 places and let the lifters fall into to path of the connecting rods,and BBLLLAAATTTT!!!---no more 400...
I hope you can salvage the crank to use in a 350 stroker motor--looks like the heads are toast(or at least need a valve job if they arent cracked)--I havent seen a cam push the expansion plug out the back like yours did(or did you do that?)--my condolances on your loss--I know how it sucks to spend time and money on something,then have it not pan out like you hoped,been there,done that....
A moment of silence for our fallen 400 small block--another of chevys rather rare and best motors passes into oblivion--R.I.P.
Not making fun of your misfortune--I hate it when a chevy motor blows up,and its frustrating to not know what caused it--after a catostrophic failure like this its kinda hard to pin down the exact cause...so many parts get wiped out in a few seconds at 2000+rpm its nearly impossible to say which failed first and started the chain reaction that finished it off...
How many peices was the camshaft in??--I saw a new chevy citation years ago that spit a 3 inch section of the cam ,with 2 lobes,out the side of the block.and it actually kept running long enough for the owner to bring it to the dealership my brother worked at--it blew up and seized as they were driving it into the service area --the lifters must not have fell in after the cam broke right away,but at least one fell in during the trip to the service bay,and that was its last revolution!--Your cam might have snapped in 2 places and let the lifters fall into to path of the connecting rods,and BBLLLAAATTTT!!!---no more 400...
I hope you can salvage the crank to use in a 350 stroker motor--looks like the heads are toast(or at least need a valve job if they arent cracked)--I havent seen a cam push the expansion plug out the back like yours did(or did you do that?)--my condolances on your loss--I know how it sucks to spend time and money on something,then have it not pan out like you hoped,been there,done that....
TrcksR4ME
1/2 ton status
Hmmm
Maybe there was something to that afterall...
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k10clown
Registered Member
Ouch!
That is correct. Anymore than .030 on a 400 and you can run into problems with them. Detonation is hard to fight with a 400 block because of their design, the cylinder temps are hotter than a 350 block. I've faught and faught detonation with mine and have to run 91 oct. and octane booster with a 9.2:1 motor if I am going to tow with it. I've come to the conclusion that aluminum heads for a 400 are a GREAT idea to help fight high cylinder temps. If/when I build another 400 I will definantly use aluminum heads, heck my current 406 may have alums before it's all over.
Regardless....I'll stil take a 406 over a boring 350 anyday.
Regardless....I'll stil take a 406 over a boring 350 anyday.
big_truxx
1/2 ton status
Dude that really blows!!!
I think I will stick with building off a 350 block to start. I like their waterjackets much better
and so so so versitile. you can really build everything you need off that block. 383 torquer or a long (6.5") rod 302 for road racing and still use the same block.
I think I will stick with building off a 350 block to start. I like their waterjackets much better
and so so so versitile. you can really build everything you need off that block. 383 torquer or a long (6.5") rod 302 for road racing and still use the same block.
mountainexplorer
1/2 ton status
New Theory:
After taling with a friend, here's the latest theory as to the cause.
The cam broke first. This allowed the #8 exhaust valve to hit the piston, shattering it and breaking off the head of the valve. Pieces of the piston then were sent all through the motor, and allowing the rod and wristpin to break out the section of the cylinder wall at the same time the 3 lifters and pushrods drop into the pan. Engine shuts down.
I never verified 100% that it was a true Comp 292 cam. There are no Comp numbers on the back of it. Maybe a regrind?
After taling with a friend, here's the latest theory as to the cause.
The cam broke first. This allowed the #8 exhaust valve to hit the piston, shattering it and breaking off the head of the valve. Pieces of the piston then were sent all through the motor, and allowing the rod and wristpin to break out the section of the cylinder wall at the same time the 3 lifters and pushrods drop into the pan. Engine shuts down.
I never verified 100% that it was a true Comp 292 cam. There are no Comp numbers on the back of it. Maybe a regrind?
Makes me teary eyed. So much effort and money!
MTMike
1/2 ton status
WOW!
mountainexplorer
1/2 ton status
Not much money. Just alot of trading. I had less than $100 in cash into the motor, but alot of wheeling and dealing over a year to round up all the good parts I wanted.
Looks like the cam might be a Crane Cam. Had someone come look at it and he thinks it's possobly a Crane. Its not a regrind. And it broke in two spots. I found the 3rd piece in the oil pan after we extracted the back section out of the block and noticed there was a chunk still missing.
Still unsure as to why it would have snapped so suddenly.
Looks like the cam might be a Crane Cam. Had someone come look at it and he thinks it's possobly a Crane. Its not a regrind. And it broke in two spots. I found the 3rd piece in the oil pan after we extracted the back section out of the block and noticed there was a chunk still missing.
Still unsure as to why it would have snapped so suddenly.
big_truxx
1/2 ton status
mountainexplorer said:
This also puzzled me. I did not think that cams would just come apart like that. I am also still learning though.
