They aren't fresh like they just where dropped in..... there's nothing to make right from the builder here.

I say lets see some close ups of the plugs.

Is this a single 29 or twins, is one motor hurt and the other one fine ?? Eliminator you make reffenence to motor's

I've not said anything bad about Eric or anyone there if you'd read what was said, it was just asked who built it. I'm not in any way implying they don't do reputable work, they do. The whole reason behind this post was to try to find some suggestions on what types of things could have causes a motor with 9 hours on a complete build to suffer this type of catastrophe. You've got some pretty bad info from wherever your source is. I waited from October of 2012 and did not have the motor back in my possession until January of this year. The first time out with it was not until 4th of July weekend, 4th of July to be exact. Your claim to 30+ hours on my "motors" in a single engine boat that I've had the key "ON" for a total of a little over 9 hours are just ridiculous. I have talked to Eric several times throughout the process and several times this week about the issue, never said he was being a dead beat or implied anything of the sort, he said he's willing to help me out. The pump did not quit that I ever noticed and being I spent every trip out getting used to the new engine and fixing minor problems that popped up and especially paying attention to what the gauges were showing. Wasn't saying Eric is responsible but just threw me off that once I discovered the problem the first solution was that the wrong plug was being used and I should swap them out.

He'll ya, and little Smith can dang sure paint! They're building a 509 for me right now.

Following is just conversation:

Blow thru carb's aren't the most trustworthy thing on the open water.
I'm a diehard carb guy, but with blowthru's I personally would go EFI/ Agai, just personal opinion and conversation.

Basically I'm waiting for full report of this engine before I listen to what may have happened without evidence.

He'll ya, and little Smith can dang sure paint! They're building a 509 for me right now.

I built my two engines in a 302 Formula I had a few yrs ago. Beat them senseless for 2 yrs, always changed oil every 15 hrs. They ran tops until I filled up at a marina I hadn't ever been to but was super low on fuel. Fired up and blasted home. Half hr into the ride at 3/4 throttle or 4600 rpm lost an engine. Pulled heads and pistons where destroyed. I didn't hear detonation. Pulled other heads, major damage in that engine also. Pulled fuel sample and did an octane rating. Came back @86 after mixing with my 94. I had paid for 93??? Marina owner told me I was full of $hit and to pound salt, I didn't wait around to see him wake up. So check your fuel in the boat could be that not the builder.

I would have pissed on him so he would wake up and I could do it again. I know the marinas in my area aren't regulated as much as on the road and they get away with less minimums octane in the tanks. I know a guy that will let fuel sit in the tank all winter and sell it in the spring. What a POS.

I don't promote this sort of behavior.




But !!!!!


Good for you !!!!!

LOL. Wow.

This sounds almost exactly like what happened to mine, we rode for about a half hour stopped, 2 hours later the thing would barely start much less run at all, I knew there had to be some sort of unknown damage going on well prior to that. Obviously something finally gave up though. I filled both cars with it last night as I'm draining the tank again, I'll be mixing new with race gas when it's done. We filled up with around 45 gallons prior to this trip so I couldn't help but see that as being the root of the problem. I'll post some pics of the plugs when I get a chance, I didn't take any while I was doing the compression test other than the smashed one.

And I said check the marina. Have one here that sold 110 and messed up and had it switched too 91. Blew up guys engines and he was told too pound salt too. I also don't believe half of them with no ethanol. Here's my deal I bought a brand new ranger and filled from the same marina for 3 years. Went out a month later and boat died. Two gummed up fuel pumps and all new fuel lines plus clean injectors later all from ethanol. This marina has a big 10 foot by 3 foot sign "no ethanol" ..... lost my biz forever and gave too mechanic down here too show what lies and decite they are capable of.

Which marina on which lakes guys?

Cole I can't really say cause I do all their fiberglass work. But ask any high performance boater on gRand and they will tell you. I buy all my gas now from serenity point. Their 91 came back at 93 this summer. ConocoPhillips tested it for me through a friend. Not one drop of ethanol. Just sayin.

Ok, I run a simular setup, if it ran decent for a while, where was the timing set at ? I run AC R42TS for over 3 years now, timing @ 28, you can get one the small camera's and look thru the plug holes to see that things look like, but going to have to come apart I'm thinking...again pics of plugs would help...Rob

You have to pull the heads and see whats up. No biggie, without air tools have them off in less than an hour. Never mind bore scope, plug reading. You know ZERO compression in one of the holes. Pull them and post pix after you tweek out and dummy a few beers.Bet tops of pistons look like the surface of the moon and valve heads if still there coated with rough grainy aluminum sand. Feel your pain Bro...

That's my thoughts about it too but in not even pulling the heads right away, taking the whole thing out because I'm 110% sure the pistons are gone at the very least. Hoping with stock cast heads that they've faired a little better, will know once it's out.

Dont rule out your intercooler,,it might have a hole in it and injecting water into the carb..you said hard starting which the engine could have been trying to start on water with the fuel.. pressure test the cooler..

That thought crossed my mind last night too as I was starting to get it ready to come out, as well as testing the headers. Cooler was tested before it was used but definitely worth a second look.

Well guys I've got an update....
Pulled the engine Friday and tore it down this afternoon and found out the exhaust valve seat on #4 cylinder was gone, and pieces of it had visited all the other cylinders. The pistons looked like someone took a punch and a hammer and beat the tops, #4 being the worst by far and the heads were pretty well matching. The cylinder walls have some marks but nothing horrible, but I suspect the heads are beyond repair and one of them was new with the build as the original was cracked. The valves are about 50/50 as far as being salvageable. The other cylinders look like they've been running rich and burning properly as they should have been. Not sure what would have cause it to come out but one thing I did notice was with a thermostatic oil cooler and no thermostat the engine temp would take some pretty heavy temp swings. Guess I'll be making some calls tomorrow and see where to go from here, get things going so we can have her going again by boating season!

The "punch and hammer " marks would be detonation.

You win.

I would not go chasing the cause of this problem, with thermostat issues.

You had spark plugs with the gaps closed up, hammering marks on the pistons, and a valve seat failure.

Just because it appeared to be running "rich" doesnt mean squat. Fuel mixture is only part of the battle against preignition/detonation. I'd be looking at the fact you have a boosted engine, that had possibly too hot of a spark plug, with a projected tip. The projected tip plug will light the fire sooner than a non projected tip. If you had the timing advance too aggressive, the projected tip was probably making the situation worse, as was the hot heat range plug with boost. Running "rich" isn't gonna help a poor setup that's asking for detonation.

And a blow thru carb in a boat. Be careful !

Edit in: check, recheck, and again recheck you are not leaking any cold water thru the exhaust.

Guess I need a better description, it's not little pits and marks all over, it's big chunks stamped in random shapes all over the portion of the head where the piston almost meets, along with debris lodged in the pistons and head as well. The marks are up to 1/8" deep or better and up to almost a 1/4" in diameter.

I'm with Mild on this one. The only thing running rich will do is help show that the motor is detonating. It's not the first light that's get you it's the continual light that does. If it was me. I would start with a number 11 NGK plug gapped @ a very tight .023 and go from there if you gap your plugs correctly you can tell if the motor is detonating if the gap opens. It will only open .001-.002 the more you open the gap on the plug the more heat you give it and a better chance to keep the mixture burning.

I`m pretty sure here that your headers may be too big .


:party-smiley-004:

Maybe this will help explain it....:party-smiley-004:


http://youtu.be/43Lg5dA3nLY

Improper exhaust dimensions can / will add more reversion (intake + exhaust) tendencies esecially when at 'worst length'.
When the energy wave comes back to the valve and it's open...slurp.

Serious.

:poopoo:

i think the op said he has cast heads.i have seen the merc iron heads drop exhaust seats before.some of them had improper sizing when they got machined for the seat and when they got hot the seat came out.iron heads on a procharged engine is asking for trouble imo.

Very true. And an easy way to tell if this is happening is look at the intake runners / ports in the head if there is evidence of carbon then the cam, exhaust or cam &exhaust aren't right.

My buddys been doing pro charged 509's blow through for 7 years, no issues....

Does not take much to have leaks in the intercooler, pressure check it, my buddy has gone through 2 of them over 7 years... luckily he has tons of monitering on the boat and saw things not right before it failed..

What was timing at? I didnt see that said anywhere, there are many things that cause this... timing is a huge factor people overlook...and plugs... but you guys got that..

we have run blow thru carb setups(done properly) and had no issues...

Exactly what I found when tearing down my HP500 . Wonder what was left on the table running the stock Gill exhaust .

I would imagine a good bit. When this occurs the cylinder is not getting cleaned out. A good clean mixture can't get into the cylinder and its going to re-burn the already spent charge. There are many factors that can cause this to happen bad valve springs/ valve job, exhaust, cam cylinder head ect ect. This phenomenon really has me wondering how beneficial it would be in a custom build to bolt the exhaust on the head and flow the head same with the intake. Based off those numbers then cam the motor. I think this would give the best package...

I was at 300 hrs. on the valve springs . It also appeared the head gaskets were seeping between cylinders . It was definitely time for a refresh/power upgrade .

Don't waste your time with flowing headers. Use proper dimensions and you are good to go.

One thing that does make sense to flow on an exhaust is the muffler...if it has one..

Edit in: a 'spent' charge cannot reburn. It does, however, occupy space that fresh air/fuel should be occupying, and thus will be down on power.

BTW: I learned the hard way many years ago that I was losing almost 40hp on a mild 375-400 SBC.

It was the headers - wanna guess how ?

It's something I have never overlooked since then and I have seen it as an issue almost a dozen times since then.