Thanks for the replies, guys. It might come down to just running it and keeping an eye on the oil and the idle speed. Mike, I was idling it around 800 RPM most of the time. Might bump it up to 900 or so just to be safe, at least when not shifting. When I ran it for a little while last night, I looked up inside the collector and it was wet clear up to where the primaries connect to the collector. Now it did shut down on its own because I let the gas run out inadvertently, so it's possible that it took a big gulp while it sputtered to a stop. I had to quit for the night after I found a cross-threaded plug on the #7 cylinder (another long, sordid story). Still haven't been able to run it again until I deal with that.

I talked at length to Jan at Lightning, and he thinks I am pulling water in at the joint. These headers were originally designed for silent choice, but the slip in collectors are used for larger cams. He said to use silicon to seal that joint and see if that helps. He did not seem to think limiting water flow to the headers is an option, but many on here would disagree I am sure. SB, what modifications would you recommend on those collectors? I was seriously thinking about welding a bung on them to dump excess water and then close up a couple of those holes up on top. I agree that it does not seem like an optimal design to me, and I can't see where that much water out the exhaust is needed to cool the hoses and the tips.

Verified that timing is around 34*, with a 24* module and 10* initial timing. Guy at Lightning mentioned that some guys like to run more initial timing or even with timing locked all in to help with reversion. I have access to an HP500 20* module, which would allow me to bump up my initial timing. Would this help or hurt?

I think you are worrying to much ..Put the engine in..........don't overthink it

I think it is the nature of the beast on these headers, I have the same and can tell they get water back in, as you know I did the water bypass on mine trying to get the 02's to live, F on that...but they dump water so close to the collector don't think you can get around it...I'm running a 500HP carb cam and know they are iffy on reverting...I talked to lightning as well and they warned me against my water dump idea, but we ran and checked one side with valve open bleeding off water and the other closed in stock position and did not show much temp change from one side to another, but that was about 20 mins running...still want to test some more...Rob

IMO, the whole silent choice thing is nothing but a royal pain in the azz. We have more than enough options today for sound control. Air operated mufflers, full time clamp on mufflers, muffler inserts, turndowns, etc. I'd throw those silent choice diverters in the dumpster, and have someone make full jacketed pipes thru the transom and throw some mufflers on it.

I have Stainless Marine TRS dry to the tip manifolds. (3' of tail pipe) When I pull my O2 bung plug they will revert water back to the manifolds. The those need to be sealed good. Also I have never seen dry stock lightning headers at an idle. I have to agree with ezstriper.

Rob, you have the silent choice on yours as well, right? Is there any kind of inner pipe that slides into the main body of the header?

If I were going to modify mine I would consider adding a dump outlet on the separate collector and close up several of the water ports on the top. Might just do that before the season is over. Any good welding shop could handle it, and I could easily cap off the dumps if I decided not to use them.

I just removed the drains off the rubber log that feeds the tubes, installed a simple shutoff valve there(they were different sizes on mine) and I just drilled and tapped my Y pipe 3/8 pipe, not hard, ran a line from the valve to a fitting there, you can adjust how much water you bleed off...talked to Bob M. about this and he liked the idea of getting as much water as possible away from the engine...

I don't like the slip joint and I don't like those holes in the inner pipe letting the water rain down into the exhaust stream.

I would have an inner pipe made/welded in that is as long as you can fit with a slash cut - top longer than bottom. A 3 1/2" iner with 4" outer (outer can be rubber or metal).

The bravo pumps mover so much water that your exhaust won't burn thru if using rubber and the 1/4" or so gap from outer to inner won't have a smooth ramp for water to get sucked back as easily as most companies risers do since they roll/flare the inner pipe OD to outer pipe ID with water outlet holes of course. That's too smooth of a transition and thus does nothing to deter water from going backwards.

Alot of people in the small block and small boat world - smaller pockets in this boating category - do....even with stock or cheap GLM exhaust - ie: weld inner extensions on to the outlet of the inner part of risers. Bam ! No reversion, or , a ton less. Edit in: typically 3" inners and 4" outers as small blocks don't need more than 3", and the added bonus more of a step between the inner and outer where they terminate.

Get the water introduction further away and make it harder to come back up backwards. This is what has to be done before modifying water supply, overboard dumps, etc,etc as these should be final straw if needed.

Your cam is mild !!!! Just get all water away from the area just after the inner collector starts.

The whole problem might be that it is not getting to true temp. Too cold for a true test under these conditions.