Sutphen,

They are open into coolant passages. Which is how this all started. Sorta.

What that pic shows is how deep the bolt was in the deck of the block. Where the “goop” ends is at the deck.

Thanks. Brad.

Don’t take this the wrong way because it’s not meant with any disrespect, but do you feel maybe you’re causing your own issues? I have been doing this a very long time and very very familiar with the 496s. I’ve worked on many of them and owned many of them. I never had the issues that you are trying to correct, is the builder you’re using a professional builder or is he doing it on the side as a favor out of his garage? He should’ve been the first one to tell you about the bolts not being long enough when he originally put the cylinder heads on, again you’re about the only person that I know having all these issues with a 496.

maybe I am missing something

Wildman,

the only “issue” was a coolant leak we fought all summer. After trying to get to it in the boat, the decision was made to pull the engine. Initially thinking it was a bad circ pump, I ordered a new one. Upon disassembly, I found this:




The connecter between the crossover and the circ pump. It’s my assumption that this was leaking. I also decided to replace the T-stat with a 120°, and, while in the process, discovered that the T-stat seal was all but crushed out. It was hardly proud of the top face of the crossover. So I ordered a new seal. All that’s back together.

While it was out, I decided to swap the cam for a Raylar BP211, so the exhaust manifolds, intake and valve covers came off, along with all the other crap that has to come off for that project. While this was all apart, I noticed what looked like oil pooled around the external head bolt heads. I mentioned it to my tuner, who indicated it couldn’t be oil, as there’s no oil there internally to leak. During discussions with Larry at Raylar about the cam, I mentioned it to him. He enlightened me that it wasn’t oil, but coolant. If the head bolts aren’t properly slathered with sealant, coolant will seep up the bolts, leak out, dry and cook into a slick, brown substance that resembles oil. Going through my texts with my builder, I remembered that he’d told me he’d reused the head bolts, so I decided to replace the head bolts, and ordered new FelPro TTYs. While replacing them, one of them snapped before coming to torque. So off came the heads, to get to the bolt stuck in the block. While the heads were off is when we did the rocker stud work, which allowed for options on rocker studs, leading to a much better rocker geometry. While doing all this, Larry convinced me to get a set of the ARP head bolts, which ultimately turned out to be too short. It’s my understanding that they work well with the aluminum heads, but my guess is that the iron heads are a bit taller, at least at the head bolt bosses. So here we are.

Clear as mud?

I just wrapped up replacing the head bolts with the CAT bolts mentioned above. I can start putting it all back together now. Again.

Thanks. Brad.

BoatNT,

Read my response to Wildman. And no offense taken. But, honestly, would you be OK with the depth of thread engagement shown in that pic above?

To your question,

The builder from last winter is a service tech at a local m dealership, and has been building (mostly) high HP marine engines for a very long time. I do not doubt his ability to build. I think he made some decision on my behalf, trying to same me some money, because he knew the nickels and times were starting to sting. I wish he hadn’t done that with these couple issues, as I’d have sprung for new head bolts and that crossover connecter. They were cheap. But…. On the bright side, I got a new Raylar cam in while I had the engine out. So, all good.

Thanks. Brad.

can you put up a pic of the long bolt w/ the next shorter bolt that goes in the end of the head under the valve cover.I don't like how little thread is engaged.

Sutphen,

If I understand you correctly, I don’t have a pic with the 90mm ARP bolt. They are all installed and I’m not pulling one of them to take a pic. I can tell you, though, that they are ~4mm longer than the TTY bolts are spec’d as. I have plenty of of thread engagement there.

Thanks. Brad.

CAT bolts have been some of the highest quality bolts produced. With the current outsourcing potentials, who knows today.

A 170k bolt is strong. A 1/2" bolt would hold up 33k pounds...and 20k pounds in shear.

Dan's suggestion for studs is valid for a single engine offshore. Twins makes it difficult to remove heads with the engine in the hull. But typlically easier to temove tue engine to do major work anyway.

Tartilla,

I’m doubting CAT has settled for substandard components. Outsourced or otherwise. Just too much liability.

Yup. I don’t disagree with the suggestion for head studs. They are just too far out of the budget, and not really justified for a build of my level. Especially considering we are still dealing with M10 threads. But this doesn’t mean I don’t want to wring as much as I can out of them as I can. Which I think the CAT bolts satisfies. It does amaze me, though, that ARP doesn’t have 110mm long M10 bolts. It also surprises me that Raylar shipped 100mm bolts when TTY spec bolts are 103mm long.

Overall, I am very confident in what I’ve put together at this point, as Frankenstein as it is.

Thanks. Brad.