Engine blew up
08-13-2009, 06:49 AM
#1
Drifting
Thread Starter
Engine blew up
A few days ago my engine blew up. I was getting ready to do
a full rebuild anyway, but that doesn't make me feel much better.
Here are a few pics:
I still didn't open oil pan to check other damage, I'll do it in a next few
days. What worries me is the reason why this happened.
It looks like intake valve on cylinder nr. 8 broke and distroyed the piston.
I revved the engine high when it happened (6500+) but I would expect
something to brake in the short block (it still stock) way sooner
than anything in the valvetrain. I have LPE valves prings with
titanium retainers, so 6500 rpm shouldn't be a problem.
a full rebuild anyway, but that doesn't make me feel much better.
Here are a few pics:
I still didn't open oil pan to check other damage, I'll do it in a next few
days. What worries me is the reason why this happened.
It looks like intake valve on cylinder nr. 8 broke and distroyed the piston.
I revved the engine high when it happened (6500+) but I would expect
something to brake in the short block (it still stock) way sooner
than anything in the valvetrain. I have LPE valves prings with
titanium retainers, so 6500 rpm shouldn't be a problem.
08-13-2009, 07:56 AM
#3
Safety Car
My gut feeling is the valve floated or dropped and kissed the piston resulting in the damage. Why did the valve float or drop is the question. It could have been weak or damaged springs (broken), a valve keeper failure, a pumped up lifter combined with weak springs, a retainer failure, a broken valve (least likely), or other?
08-13-2009, 08:17 AM
#4
Race Director
several possibilities. Sorry to see that kind of damage
One of the reason I don't rev higher than 6100-6200rpm with my hyd-lifters. My shift light goes off before my tach registers the rpm so if you saw 6500rpm on your tach, it was quite possibly higher
08-13-2009, 09:39 AM
#6
Team Owner
Member Since: Oct 2004
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St. Jude Donor '05
that sucks...one reason Im not a big fan of running a HR up high. Valvetrain can last years or a week when twisting it.
08-13-2009, 09:41 AM
#7
Safety Car
What lifters? Most hydraulic lifters can't stay pumped up above ~6000 RPM.
CompCams didn't even recommend that I take my "racing" lifters to 6500.
CompCams didn't even recommend that I take my "racing" lifters to 6500.
08-13-2009, 01:24 PM
#8
Drifting
Thread Starter
I just pulled the engine but I didn't open it yet.
As I said, I planned to do a rebuild in near future
so I have a lot of parts ready.
I have a spare 2-bolt 1-piece RMS block, but I planned to
get that block splayed and use it for 383. So I really
hope that I'll be able to reuse my current block.
I think that I'll be able to fix the heads.
I have a local company that makes valves and valve seats
so I'll probably buy new valves and seats (2.02/1.60)
from them. They have a really good reputation, so that
shouldn't be a problem. Also, I think that I'll have them
made with thinner, 8mm stem and have some custom guide fabricated.
I know that it would be a lot easier to find used heads
and block and start a rebuild from that, but have in mind
where I live. Finding Chevy V8 here is really hard.
I plan to use different cam and fully port superram
but I'll get into more details later, perhaps in a new thread.
I'll probably open up the engine tomorrow and be back
with more details about it's condition.
That is also what I'm thinking. I've revved that engine high
on regular basis and I geuss that I was really playing on the limit.
I have valve spring tester so I'll check them but just out of
curiosity. I'll need stiffer springs with new cam anyway.
Lifters were stock replkacement from CC's.
As I said, I planned to do a rebuild in near future
so I have a lot of parts ready.
I have a spare 2-bolt 1-piece RMS block, but I planned to
get that block splayed and use it for 383. So I really
hope that I'll be able to reuse my current block.
I think that I'll be able to fix the heads.
I have a local company that makes valves and valve seats
so I'll probably buy new valves and seats (2.02/1.60)
from them. They have a really good reputation, so that
shouldn't be a problem. Also, I think that I'll have them
made with thinner, 8mm stem and have some custom guide fabricated.
I know that it would be a lot easier to find used heads
and block and start a rebuild from that, but have in mind
where I live. Finding Chevy V8 here is really hard.
I plan to use different cam and fully port superram
but I'll get into more details later, perhaps in a new thread.
I'll probably open up the engine tomorrow and be back
with more details about it's condition.
My gut feeling is the valve floated or dropped and kissed the piston resulting in the damage. Why did the valve float or drop is the question. It could have been weak or damaged springs (broken), a valve keeper failure, a pumped up lifter combined with weak springs, a retainer failure, a broken valve (least likely), or other?
on regular basis and I geuss that I was really playing on the limit.
I have valve spring tester so I'll check them but just out of
curiosity. I'll need stiffer springs with new cam anyway.
What lifters? Most hydraulic lifters can't stay pumped up above ~6000 RPM.
CompCams didn't even recommend that I take my "racing" lifters to 6500.
CompCams didn't even recommend that I take my "racing" lifters to 6500.
08-13-2009, 06:26 PM
#13
Safety Car
That is going to require a lot of re-work of the #8 combustion chamber. 
I would bet if you saw 6500RPM on the factory Atari gauge, you were much closer to 7K than 6500RPM.
I would bet if you saw 6500RPM on the factory Atari gauge, you were much closer to 7K than 6500RPM.
08-14-2009, 10:21 AM
#15
Team Owner
Member Since: Oct 2004
Location: altered state
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St. Jude Donor '05
Thats a lot of rpm to be trusting a stock bottom end with, they werent meant to be taken there.
Hopefully they can weld up and repair your head, Ive seen worse fixed.
Hopefully they can weld up and repair your head, Ive seen worse fixed.
08-14-2009, 11:03 AM
#16
Drifting
Thread Starter
Heads shoudn't be a problem. I've ported and polished
around 100 heads in last 7 years (mostly for european 16v engines),
but I have all tools and equipment for that. The most difficult
part is to get new valves, springs.....
I'm more worried about the block. I'll know more soon......
around 100 heads in last 7 years (mostly for european 16v engines),
but I have all tools and equipment for that. The most difficult
part is to get new valves, springs.....
I'm more worried about the block. I'll know more soon......
08-14-2009, 02:00 PM
#19
08-14-2009, 03:09 PM
#20
Drifting
Thread Starter
It's exhaust valve and I'm not sure why it's redish.
It could be a sign of lean AFR on that cylinder, so maybe a
bad injector......
I'll have injectors tested as well.
I have also noticed, while disassembling the intake, that intake
manifold gaskets didn't seal really good on the bottom side.
I have just put the engine on the stand and pulled off the oil pan.
I removed the no.8 rod and everything looks really good.
There is some wear on the rod bearing but crank looks like new.
I must say that I'm really pleased about that.
I did however notice that piston nr.7 looks like it's cracked also.
I'll know more when I tear it all up. I'll post some pics later on.
Originally Posted by rodj
Bruno ,
now you have some talking pieces for your workshop
now you have some talking pieces for your workshop
Last edited by Sliding; 08-14-2009 at 03:20 PM.