If he got the cams from Bob, typically he uses the 8.1 cores and the firing order is 1-8-7-2-6-5-4-3, at least they were on mine. Tim can verify this if the cam gear retaining bolts are metric threads.

yes thats firing order

Are you running water cross overs and are the back of your intakes plumbed to dump water out of them? This helps propagate flow through the back of the head. I seized valve #8 3 times within 15 seconds after getting on plane. My guides were checked and honed over and over and they still failed.

Rook, looks like this happened with #2, which should get excellent water flow being on the front of the engine.

the firing order had no bearing on this failure.tim,s new wires did not cross fire.maybe lightning struck the nearby water and caused the failure by overheating the water.

I am running the same setp I have had for 10 years with 3 different engines with zero issues.... I did not change what woked fine....

It could be as simple as a bad day at the afr plant, or lifter plant one of the 2 seem to be the cause because nothing else adds up...

I thought I was the only one that happened to. At first, I thought the burn marks on the bottom of my boat was from going to fast. :funnypost:

Oh my fault, I thought you rebuilt these engines with new aftermarket heads...
These are not the old engines out of the Scarab III?

Yes I did, so why did I not fuk up my chitty pro comps? Hmmmm

This cracks me up if I changed every detail that everyone said was a cause I would have even more money wrapped up in it, look at the big picture, crossovers, many guys run them including myself for years no issues, why change it? I mean come on.... I wish there was ONE SOLID answer on why this happened we may never know could have just been a part fail that's it, might be guides, might be lifter or other things... But sure seem to have it narrowed down... Crossovers didn not cause this, if the heads were set up as marine and I find all huides minimal of .0018-.020 I will look at later because my buddy been running crossover with 800 + hp engines for 10 years with zero issues and almost no water temp in engines....

Please don't come on here asking for opinions and then be a dick when you get some opinions. I did not say this was 100% crossover failure like others have with their opinions. I'm only asking questions to try to help with your issues. I had that failure when I switched to aftermarket heads.
I know your upset, we are only trying to help.
These are not the old engines out of the Scarab III?

Not trying to be a dik, but some of these things had zero effect on the problem at hand...

The scarab engines are long gone every part here is brand new and of good quality.... Should last more then 1.5 easy hours. Didn't even go wot at all that's bs

I will be done now I will keep my stuff off the grid it's probably better that way and figure it out with local guys that can see what happened ...

Shot in the dark see if the intake rocker arm on that cylinder feels free on the bearing.

All that was in good shape, this is so odd..

What rpm were you spinning were this occurred?

Full Force, you mentioned that you have a lifter stuck in the bore - I am assuming it is the intake for the bad cylinder. If that is the case, was there any damage to the pushrod? I would be fairly suspicious that this is the root of the problem. If the valve had galled in the guide and become stuck open, I would not expect it to cause the lifter to also get stuck in its bore, unless perhaps the valve stuck in its guide while partially open. Hope you can find the cause and get it back on the water soon. And yes, I definitely feel for you - after the problems I have had with my rig, I was also kind of wishing I could just go back to a stock build so I could leave the hatch down and enjoy the boat. Good luck with it, and please let us know if you discover the cause. Doubt if you care much at this point through the frustration of it all, but it might help a fellow OSO'er down the road.

Cole, pretty sure he said he was running about 5200 RPM when it happened.

Been on Phone with Bob M we are looking Into cause and said he will do whatever he can to help me out and have a good outcome for both of us.

we all know that pictures on the net can be hard to see clearly and it is not possible to diagnose what happened without having the parts on the bench in front of you for taking measurements and for examining.i am pretty sure i know the cause of this failure but without having the parts in front of me for inspection i could only speculate without facts.the court of public opinion will not give an acurate answer on what truly caused this failure.

Tim,

I am no engine builder. But I can't help but wonder about temp differential on a fresh engine. You mentioned you do not run stats in another thread, and show coolant temps of 100 or less this time of year. With the engine being new, and the relatively high EGT's that marine engine runs is it possible that is stuck because the valve grew but the head did not because coolant temp was so low?

Bob is a great guy, I'm sure he will do whatever possible within his means to get you back up and running.

I never ran stats and never issues before, so not sure what yet just trying to find cause at this point and how to avoid it again and other engine, very stressed out....

Well you never had brand new engines before either :D And lets face it, the water is unusually cool right now, even for this time of year. Breaking in a new engine with coolant temps under 100 degrees scares me, but I am no expert, just trying to give you some perspective.

I run 120 degree stats in mine, and right now am having trouble getting the oil temps I want, because the water is so cold.

do you have oil t stats?we must keep in mind that when things like stem to guide or lifter to bore clearance is checked the parts should be in a room that is around 70 deg f.

My oil system is stock merc, I'm sure there are stats but it still effects the temp.


Sure the clearance is set at room temp. My question is what if that head is still at room temp while operating and the valve is at 900 degrees? I think we all have put a bearing a freezer to get it to drop in a race. If the race was room temp and the bearing is hot its not going in.

Why do we warm engines up before using? I have seized a piston in a snowmobile because the piston warmed before the sleeve, no room.

I am not trying to beat Tim down, I consider him a friend. Just saying all new parts and ice cold coolant in a full load 5000 rpm environment maybe could be part of it? Don't they make stats for crossovers?

Totally get that, I never had issues with other new engines, and scott runs same setup with no issues in cold water, not to say that don't play a role but going off past not having issues, I think my lifter stuck or guide issue plain and simple just got to determine what one

your sc 575 has oil t stat from the factory.we warm up our engines because cold oil does not flow well.the snowmobile engine is a totally different anamil and cannot be compared to a marine engine that runs in much warmer conditions.

Ok, I get the sled thing is not relevant, it was more talking about metals that a direct comparison.

Yes I have oil stats. But they must have quite a bit of bypass because my new coolant temps definitely effect my oil temps significantly. Again, I am not hear to harp on Tim, I just want to learn more and discuss.

I was always under the impression that marine engines had larger tolerances because of the extreme load and the heat it makes, coupled with the cooler engine water temps. The temp delta from ECT to internal engine parts on a marine engine are much higher that a car that is running around at 180-210 all day no?

Tim, with your coolant reading less that 100, what was your oil temp?

I'm still thinking it was a machining issue, as Tim suspected. However, I am curious about ice cold engine temps, and a new engine in high load for break in. I wouldn't think it could be good but I don't know

Up here with a crossover, and this time of year, good luck getting good oil temp before you drop the hammer. And yes, even with a tstat'd oil cooler.

Fact.

Why not run a T stat with a bypass to feed the exhaust. I run crossovers and this is how I set up my engines when I went back to NA.

Same here . normal days on lake Michigan for me, with no water stats, mercury oil thermostat, and crossovers, I have to run at 3500rpm for 15 minutes sometimes before I start getting oil temp.

Bring boat to loto, warmer water, and I have oil temp in a mile.

Its fun when you have SSM drives mounted high, some rough water, and 4500rpm burnouts getting on plane with cold engines. It is what it is though, and this is why all this needs to be considered when building the engine.

All this is really making me want to hurry up and install my oil thermostat.

Oil temps were 180 before I eased into throttle

Full Force, is that just some oil or carbon on the head between the #2 & #4 cylinders in the picture that you posted? It almost looks like the head gasket was blown between the two cylinders. Just asking and grasping at straws.

That's oil gasket was fine .

Did that too. Way to freakin long to get oil temp up. And water. Then run into water psi problems, then need to do water psi regulator.

2 Summer months they where okay.

Screw that. Put factory system with recirc pump back on and never looked back.

Bingo.......

What is the water temp this time of year?

Saturday Erie, off Marblehead was 61 degrees.

What is a good marine guide clearance.... ?