News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Poss. blown head gasket, what else? 500 Eldorado

Started by mummyjohn, March 14, 2017, 03:48:10 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

The Tassie Devil(le)

Boy, what a horrible sight.

With the prevalence of replacement engines/blocks in USA, I would consider your block as being ready for the tip.   Not even good as a boat anchor, as engine blocks, especially the V8's don't work well as anchors as they tend to roll around on the bottom.

I used to race a L88 427 BBC that was blown up so many times, that it was bored and sleeved so many times, that it eventually ended up at 0.065 oversize, even with sleeves.   I was running 12.5 to 1 Forged Pistons, and it was as strong as an ox, and redlined at 8,000 RPM.   It ended up in my Dragster, after spending time in my '37 Chev Coupe Hot Rod, in a de-tuned state.   Still pushed out 550 HP de-tuned.

The only reason the block was retained was because it was an L88, and it was scarce.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

"Cadillac Kid" Greg Surfas 15364

5200 blocks and 500 cranks are getting to be a little more "pricey" than before, so I would take the motor to a reputable machine shop and see what they say.  If you can sleeve it (and it tornadoes need more than one or two sleeves) that might be your best bet. in regards to pistons, if you want a 10:1 piston I might suggest something like these. Forged Probes, Call Paul at MTS when you know what you need to do and I am sure he will be glad to help.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Phil Weber

Found this description of the KB piston on the Hemmings sight . The top ring location might explain why the top of the piston lets go.

"Keith Black pistons incorporate a higher top ring groove, which better stabilizes the piston assembly within the cylinder to prevent wear and allows for a tighter piston-to-cylinder fit. Piston crowns and valve reliefs are also CNC-machined and diamond-turned ring lands are reinforced for higher strength.

Because Keith Black-style pistons place the top ring up higher on the piston, and the pistons make more horsepower by reflecting heat energy back into the combustion chamber, the top ring runs hotter and more end gap is required than on a conventional piston. Increasing ring end gap does not affect performance or oil control because end gaps will normalize once the engine reaches operating temperature. "

Phil

V63

Could this initially be a case of hydraulic damage?  :o

The cylinder started filling with water, while it was running until finding enough volume that was uncompressable?


Jeff Rosansky CLC #28373

I would agree with you if this was on startup, not while running. Everything happens too fast when running. Difference is "watching" it fill with water vs blinking and it's full.
Round engine airplanes need to have the prop pulled thru a few blades and when you finally hit the starter you have the key off for a few rotations so it doesn't start at first. This is done because oil from the crankcase will drain into the bottom cylinder. No need to worry about it when running. This should be the same.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

"Cadillac Kid" Greg Surfas 15364

Ditto Jeff,
That's what KB tried telling me, that the ring end gap was not right.  Went back to my machine shop which does incidentally know how to read and read the instructions that came with the pistons.  I don't remember the ring gap they recorded but it was actually a little larger than instructed.  Also, Just like the OP, mine let go at a low speed, low demand event. I was just going about 55 on the highway,  The top of the piston let go, the broken pieces got caught in the damaged area and opened a nice slice in the block.  This is no mystery with the KB small chamber pistons, and by all means not an unusual event.
Incidentally, any water entering a 600+ degree cylinder would immediately flash to steam which IS compressible.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-