|12-12-2012 10:51 AM|
Fresh 383 burns up pistons
A classic case of putting a tool in someone hands that don't know his ^#% from a hole in the ground. If you don't know what you are doing ask somebody first. I am sure the machinist explained the build to him and told him what fuel he would have to use. Being cheap he fills it up with 87 octane gas. Unless he was running an open exhaust he must have heard it pinging. Probably with the brand new Holley bolted it on with no tuning so it was probably running lean. There is no way that the spark plugs would have read normal with that much damage.
|12-12-2012 06:43 AM|
Engine must have been singing to you (pinging/knock).
head design makes alot of difference also. Newer Vortec heads may help because of chamber design but looks like detonnation as stated. Lots of fuel wash indecated by carbon deposits but todays world fuel is very inadiquet for this type of compression. Fuel additives state they may raise octain rating 6 points but in reality it is maybe 1 point at best.
|11-07-2012 06:17 PM|
|1Gary||You guys did see the O/P's post date pf 3/12.|
|11-07-2012 05:32 PM|
It kinda looks like it was built a little to tight and when it knocked a little it fried it. Not all builders bore the cylinders the same size. I bet they are under spec so the builder ate the cost.
Also do you have one of those silly rv cams. Go bigger i know its a truck but a little bigger will help save the new engine. Maybe even run this by the builder and pay for the cam upgrade will solve a lot of issues. I am reallly hoping he did not build a 383 with the stock 350 cam.
|11-07-2012 09:14 AM|
|Gus's 40||yea mine does to all over the firewall and motor but not all the time, I took the breather off the drivers side and put a pcv valve with a baffled grommet and put a piece of foam filter under it and think it might be to restrictive|
|11-07-2012 05:04 AM|
oil out breathers
funny you say that i seem to have the same problem not sure the cause was told might be because high pres oil pump its not alot but it does make a mess
|11-06-2012 03:30 PM|
|11-06-2012 03:00 PM|
If I were the builder, I'd tell you to go pizz up a rope.
|11-06-2012 01:37 PM|
|Gus's 40||You got me wondering about my 383 I have aluminum heads, cam has .480 lift 109 lsa and 230 duration at .50 it is running a little rich right now but seems to run good but I do get oil coming out the breathers|
|11-01-2012 11:00 AM|
Hyper-eutectic pistons are quite intolerant of this as are most cast pistons, but high silicon aluminums including that used in forgings are more brittle and do not transfer heat as quickly as lower silicon alloys.
These alloys also tend to break up, this was mentioned in one of the early replies, if you look carefully at the pictures you can see a crack running from the ring lands into the pin boss. Fortunatly the owner burn't holes through the crowns, lost compression resulting in the engine quiting just in the nick of time leaving him a rebuild instead of a replacement. Pushed a few seconds more, this engine would have been pieces on the pavement.
So when running hyper-eutectic castings or high silicon forgings it is extremely important to stay out of detonation. If you're inclined to push the limits do what the factories do, put a detonation sensor on the engine. It is not difficult to install one such that when it hears pinging it kills the ignition. With a computer in the ignition loop that controls the advance electronically the detonation sensor can be used to back off the advance which is more gentle on the parts than just shutting off the ignition. However, either will save the motor. Detonation sensors don't work with gear driven cams as the gear noise trips them up.
|10-31-2012 06:39 PM|
|Redcar||i have the same type of pistions 383 60 over with 500 miles on it sound like a break in problem but i just did want the machine shop said what to do but i do have to say that it was running fat for the firts 300 miles|
|05-28-2012 10:18 AM|
Look and find how the oil got into the combustion chamber!
I think thats what caused the problem
I dont think it was timing
Looks to me like oil caused the detonation this can happen really fast!
Are you runnind a pcv system?
Also check the valve seals
It could have been timing,but I doubt it.
|04-02-2012 10:38 AM|
|CNC BLOCKS NE||
I am sure the engine being over timed will cause the pistons to run hot and expand and cause this damage!!!
|04-02-2012 08:45 AM|
|WARREN BARBER||It's odd that nobody notices all the rings are pretty much lined up. The scuffing on the pistons skirts looks to be caused by to tight a fit. Not due to original clearances but do to massive overheating which in turn caused the detenation concerns. who ever put the engine together didn't know what they were doing and probably didn't purge the cooling system. This is the only way this mush damage could be done to an engine in this short amount of time. Unless NOX or just all out racing and no break in period.|
|03-29-2012 05:27 AM|
Ayuh,.... Agreed,... The owner Smoked that motor....
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