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iTrader: (1)

was wondering if someone would pick up on that .... we just cracked the cover and she peeped in from the back seat ........

Tinkerer

If it is a lean condition it would take time for the valves to heat up and cause the POP.
If it was a coil or wires it would just be a MISS not a POP.
It has to be something related to the valves - lean mixture, valve float, sticking valve.

offthefront

iTrader: (1)

going to take some plug readings this weekend ...go from there ....

alcor

My money is on leaning out. Experienced the same think after having the wore out 454's that where in the boat when I bought it rebuilt. You know, the ones that are supposed to have low time on them and run great , that's another story.

Anyway, after total rebuild of everything, engines carbs, alternators, distributors etc. heard that pop through the carb, mostly on the port engine. Well after the inital 15 hours of messing around swapping parts etc., finally got around to plug and vacuum readings (like a nubmer of OSO guys were suggesting) which quickly revealed the problem; way, way to lean! Probably the only reason they ran before the rebuild was they were so wore out when I bought the boat, the blow by was causing teh plugs to be black, but even then they pooped once in a while above 4000 rpm. After total rebuild, plugs went instantly to stark white . Long story made short, started re-jetting the 750 dual pump Holley's two steps at a time; went from #70's on the primary to eventully #88's and the secondaries went from #80's to #90's. Plugs started turning beige and they've ran great (no popping), well except that unknown to me, the damage had been done to those nice freshly rebuilt 500 hp 454's.

Since I had messed around with it for those first 15 hours or so before I found the lean issue, by the time I resolved the problem, I had about 25 hours on them; port engine dropped a SS Manley intake valve at 35 hours , went from 3800 rpm to zero in about 3 seconds and locked it up! You guessed it, total rebuild due to hydro lock; cracked pistons, bent rods, two crack cylinders, it wasn't pretty. The mechanic that had rebuilt it 35 hours earlier called and said, "man, these things have been running lean, found play in a couple of valve guides after only 35 hours...........". That made me pull the heads on the other engine and had them rebuilt again; found play in a few of those valve guides and excessive wear on the seats, replaced guides, valves, seats and everything just to avoid possibility of maybe dropping a valve in that engine and causing the same major damage. That was another $5,500.00 not counting the 1.5 karat ring I had to by my wife since I had now spent about $15,000.00 on boat engines I'd only had for about 10 months; she calls it "her boat motor". It was worth it, didn't have to hear about it anymore after that !

What I'm saying is, CHECK THOSE PLUGS AND CHECK THEM NOW! Re jet while taking vacuum readings a various rpm's, write them down; vacuum will drop with each re-jetting until you get it right and then vacuum will begin to increase when you've gone pass the right jets, that means you got to rich. Change jets 2 steps at a time, if you've got 70's go to 72's take vacuum and plug readings again. I know, dyno it and be done with it. That's great except I can't afford a dyno and didn't know anyone that had one, besides nothing like seeing it under real (load) conditions assuming you don't take 25 hours to correct the problem of course . With #70's and #80's, I had 6 inches of vacuum at 3000 rpm when I started rejetting; with #88's & #90's, the vacuum readings were 12 inches at 3,000 rpms, no more popping, plugs beige.

Where did I get all this wisdom, right here on OSO, (thanks Stephan30, Formula31 and all the other guys that posted for me) the greatest source of information you'll ever get on this boat stuff and it's free!

Hey, if this isn't the problem great, at least I've past on my experience and hopefully someone benefits from the post just like I did about 6 months ago. Good luck and let us how you make out.

offthefront

iTrader: (1)

pulled cpl of plugs ... if anything Starboard side (right) looks leaner ...going to change the fuel filters ....and on the oil consumption there are oil coolers ....anyone heard of cooler developing pin holes ? I am loosing about 1/2 Quart an hour ...

sorry bout the pics ...not very good

mcollinstn

Can't tell much from the pic about the plug on the left, but the one on the right is running lean and hot. I see enough from that to tell you have a fuel supply issue to that cylinder (fuel pressure at WOT, or some other fuel delivery issue).

The one on the left, can't tell much.
You'll need to put in fresh plugs, and then do a couple of hard passes and then show us some pix.

But don't do any pulls until you determine the cause of your lean-ness.
Fit a fuel pressure gauge near the carb. Have somebody watch it while you increase speed gradually to WOT. You should maintain 5-7 psi from idle to WOT. It would be great if somebody could verify what your FP is when the motor starts popping.

Edward R. Cozzi

Can't see the tips in your photos.

If your oil cooler is where you are losing the oil, you should see it in your exhaust water.
The oil pressure is higher than the water pressure, so the oil should get added to the water rather than the other way around.

It's usually a mess in the water and easy to spot.

Edward R. Cozzi

I had my wife show me how to save and lighten your photo.
Mcollinstn is correct with his diagnosis.

formula31

http://dragstuff.com/techarticles/ho...ead-plugs.html

The color of the porcelain means very little if anything.

Formula Outlaw

From what I can tell it looks like the one on the left is burnng a little rich, looks a little carboned up, and the one on the right looks okay. Maybe I'm just seeing it different on my screen.

I always thought that a plug should be tan in color, more light light tan, light grey or white meant running too lean. Black obviously carboned up/too rich.

When I dialed in the smoothbore carbs on my ex-bike, I went through two coffee cans of plugs to get them exactly right. Once set, I ran the bike 25 thousand plus miles and NEVER adjusted the carbs again.