Re: HP 500's and a milkshake
 

My issue was that I didn't want to throw a couple grand at something that wasn't going to solve my problem when a decent glob of epoxy on a mounting stud would. The engine builder did guarantee that the epoxy would fix the helicoil and I trust his work; I was just questioning the course of action regarding the manifolds.

The internal flappers make sense to me, I'll order some and see how they do. I didn't think they were necessary since I didn't have them before, but I did get a better seal on my exhaust outlet flapper on the silent thunder box before I removed it. The internal flappers sound like cheap insurance.

Thanks for all of the suggestions.

Re: HP 500's and a milkshake
 

T-N-T Sales
The 1998 382 does have internal flappers in the tips, the old boat with the 454's did not have any flappers, but the mufflers would help stop water from going back up the exhaust. As you said the disruption from the flappers will also help this problem.

Re: HP 500's and a milkshake
 

I haven't heard of the a reversion problem on the 454. The cam profile has less overlap than the 500 Merc.

Re: HP 500's and a milkshake
 

I had the same problem that Wags described. Had three holes in the inner pipe where it was swedged to the outer. I ran the motor on a test stand, homemade 502 with iron heads, roller cam.. doesnt matter. I could see the water being sucked up the ID of the pipe and in 2min of run.. idle the oil was milk!!
I cut the pipes down because they were the tall version from a Tripple engine boat. I shortened the outer pipe and welded metal rod to the inner pipe that made somewhat of a seal to the outer pipe. Left three spots about 1/4" wide evenly spaced around the pipe. No more reversion.. I did have the rubber hoses to tips on the transom. If Gil would rebuild them for a reasonable price, I would recommend doing that, to make the problem go away.. The flapps may do it, but as soon as a flapper goes, more milk. And that cant be good for those main bearings..

Good luck
Dick