Logo
FULL SITE MENU

Hole in piston

Kimcrwbr1......funny you should bring this up :p:p:p:p
have the distributor gone through and set up with a marine advance curve
Click to expand...

Chris
Dockside Marine Services.........Tell us what curve you would use???:rolleyes::rolleyes::rolleyes:

Here we go again :eek:
 
daves69 said:
I might be wrong but I think Dizzy is what you get from the Number One On Chrysler 318 thread! :rolleyes:
Click to expand...
Yes, it sure is! :D That, plus a headache!

Is "Dizzy" to distributor, as what "Leg" is to out drive? If so, where's the "Z" in distributor? :D :D


And while on topic here........ the Chrysler Marine ignition curve is like a UFO....... we hear of them, but no one has proof that they exist.
 
RicardoMarine said:
Yes, it sure is! :D That, plus a headache!

Is "Dizzy" to distributor, as what "Leg" is to out drive? If so, where's the "Z" in distributor? :D :D

Leg is what it costs to fix an outdrive. (If not an arm and a leg):(

And while on topic here........ the Chrysler Marine ignition curve is like a UFO....... we hear of them, but no one has proof that they exist.
Click to expand...

This Chrysler curve is stored at the Area 51 site I believe!:eek:
 
Hey guy got an update. I dropped my distributors off at a local shop to have them re-built. Both were out of whack but the port (hole in piston) was giving full advance at 1050 RPM! S he rebuilt and bushed both of them giving me 24* of advance at 2900RMP so add the 5* initial and we are looking at 29* at 2900RPM. The engines are running great and I have 5 hours on the new one. Just for a reference it cost me $365.00 for both distributors to be bushed, curved, new points, condensers, caps, and rotors. He even gave me all the Borge Warner part numbers for future tune ups.

Before any of you dog me for sticking with points, This was what my budget could handle and I know it works!

will
 
buick430 said:
............ but the port (hole in piston) was giving full advance at 1050 RPM!
Click to expand...
Will, thank you for the update.

Will's story is a good example as to why I'm such a Nazi on ignition timing, and on checking our older and possibly worn distributors for the correct progressive advance.
All it takes is rusty and compromised flyweight return springs, and we have nothing holding back the progressive advance.

I don't know what this piston damage repair ended up costing you, but I'll be it was more than a pair of new distributors would have been!

.
 
Here is some food for though. I have been building Chrysler marine engines for over 30 years. I just put a 1964 426 Wedge in my 25 Welcraft Sportsman with a Bravo 1 HD drive. I ran it on Lake Erie for about 15 hours to calibrate it and break it it. It ran without a peep. No detonation at all. I took it to Florida and filled it up at the local station, same as I do in Ontario. Put it in the water and could not get it on top to plane as the detonation was wild. The engine runs a steady 140 and is closed cooled. I did some fuel testing, I was in the refinery business as well, and found over 25% Ethanol. The tests we did around town were from 8-44% Ethanol.
I ended up setting the primaries 14% richer and 12% on the secondaries. It now runs perfectly. I found a station that test regularly between 8 and 12% Ethanol. You can get a test kit online and test your fuel. Keep in mind Ethanol has a shelf life of 21 day's when exposed to air. Marine tanks are open systems so they see air all the time. Closed automotive system do not get that much fresh air.
Test the fuel and you may have to rich up the mix. I use a 600 CFM Edelbrock Marine carb and still had to go richer.
good luck
 
On taking a fresh look at that photo of the piston, I think I know what happened: the motor ingested something. If I'm correct, the head should have a mark as well.

Jeff
 
tolly_family said:
I wasn't saying that 2000 rpm was a good cruising speed it was just a safe rpm where the engines wouldn't ping and I could use up the old fuel, that was 10 years ago.
Click to expand...
Dan, just an FYI: pinging from Pre-Ignition and combustion chamber detonation are two entirely different phenomenon.
We can usually hear the "ping" from Pre-Ignition, but detonation is not always audible, or as audible.

Operating a gasoline engine at 2k to 2.5k rpm on a planing type hull may also be putting the engine at a greater risk for Detonation.
Typically, 2k to 2.5k rpm is a lousy fuel economy RPM, it's a lousy power and torque RPM, and it's certainly an RPM where greater detonation potential exists, IMO.


fastjeff said:
On taking a fresh look at that photo of the piston, I think I know what happened: the motor ingested something. If I'm correct, the head should have a mark as well.
Click to expand...
Jeff, Buick430 said that surprisingly his valves looked okay. So apparently his piston was not interfered with, other by than fragments of itself. Most likely the hole was caused by Detonation!

This photo was posted by Chris. Apparently one of his customers engine, and it looks like a SBC piston.




.
 
Last edited:
The head and valves had no damage. It had bits of aluminum on it, but thats about it. I think it was a combination of bad gas and worn distributors. I have not put 17 hours on it including a trip to and from catalina islands. I actually run cruise at 2100rpm making 12 knts and averaged around 11gph combined, if thats possible.
 
The head and valves had no damage. It had bits of aluminum on it, but thats about it. I think it was a combination of bad gas and worn distributors. I have now put 17 hours on it including a trip to and from catalina islands. I actually run cruise at 2100rpm making 12 knts and averaged around 11gph combined, if thats possible.
 
I expected this response. I may be running 2300 but no more. Yes its classified as planning but it only does so at over 3300 rpm. At that speed i feel like economy goes way down and the engines are working waaaayyyy harder. I understand the concept of planning and the stress that running a planing type haul at in-between speeds causes on engine, running gear, and my fuel . However this speed is easily attained and at a minimal load. at around 2500RPM the boat really starts to plow its way through the water and doesnt really increase speed and level out till around 3300RPM. The boat originally had trim tabs but they have long been removed.

will
 
Okay, but it doesn't look like the usual detonation damage--there's so little pitting around that hole.

Jeff
 
buick430 said:
  1. I expected this response.
  2. II may be running 2300 but no more. Yes its classified as planning but it only does so at over 3300 rpm. At that speed i feel like economy goes way down and the engines are working waaaayyyy harder. I understand the concept of planning and the stress that running a planing type haul at in-between speeds causes on engine, running gear, and my fuel .
  3. However this speed is easily attained and at a minimal load. at around 2500RPM the boat really starts to plow its way through the water and doesnt really increase speed and level out till around 3300RPM. The boat originally had trim tabs but they have long been removed.

will
Click to expand...
Will,
  1. You're a good sport, then! :D
  2. Why not go after some real numbers and take the guess work (I feel) out of the equation?
    With many hulls, there are only two effecient speeds; Hull Speed, and Planing Speed.
  3. 12 kts is typically above hull speed, and that "plowing" water certainly produces quite an engine load.



fastjeff said:
Okay, but it doesn't look like the usual detonation damage--there's so little pitting around that hole.
Click to expand...
Shock waves....... strong shock waves! :mad:
Jeff, I'm not an expert on this, but with my limited experience, I've seen that Detonation damage comes in many sizes and flavors.

Small.........

images


...... to large!

images



And from mild.............

images


..... to severe!

images

.
 
Rick, thanks for the compliment! My boat is a large boat with relatively small engines. I have taken them to 4,000RPM (not quite WOT) and decided that was enough for me. I am comfortable and confident that my cruise speed is not overworking my engine. If your ever in southern california, and I am free I would be more than willing to give you a ride and see what you think.
 
Will, are you going to keep us guessing as to what boat this is??? Year, make, size, model, pictures??? :mad:

Not fair.... come on now! :D :D :D

.
 
HAHA I thought you guys would know from my prior posts. I will update my signature when I figure out how. Until then, Its a 1973 luhrs 32' super. Twin 318's with paragon V drives. Im not sure of the prop size/pitch as I have yet to pull it out of the water. I am not good at pictures but will soon try when I load some on my computer. Maybe even a video with my new GOpro camera I got for christmas last year!

will
 
Docksidemarineservices said:
Old fuel will burn a hole in your piston.
Click to expand...
Hello so I have a friend who bought a bought about 3 days ago he took it in to the shop to have it looked at and they told him there was a hole in the motor he's wondering g what could cause this and they are telling him 5000.00 to fix it. I'd this correct? Or how much should it cost? And what's a short block? Cheaper .150hp marine motor Is the one on the boat.anybody know where a salvage yard gor boats In Wisconsin could be
 
Boatgirlwisconin said:
Hello so I have a friend who bought a bought about 3 days ago he took it in to the shop to have it looked at and they told him there was a hole in the motor he's wondering g what could cause this and they are telling him 5000.00 to fix it. I'd this correct? Or how much should it cost? And what's a short block? Cheaper .150hp marine motor Is the one on the boat.anybody know where a salvage yard gor boats In Wisconsin could be
Click to expand...
Ayuh,..... This antique thread is 11 years old, about a very different boat, 'n motor than yer's,.....
It sounds like you've got an Outboard motor, not an inboard,.....
Find the section for yer brand outboard, 'n ask there,....
 
Back
Top