Is it possible that lack of pressure on the test stand is causing the problem, ie waterfall effect. Also what is the true angle you're engine sits in the boat more or less than now.
good luck! Ken

oh boy... that does not look good....that is a ton of water and I think that is a design flaw to have the water exit like that.....the water needs to exit further away and use a larger opening to get the pressure down and reduce the firehose effect...... can you tap into the water stream somewhere and bypass it? do you really need all that water in the exhaust? Maybe bypass 1/2 to 2/3rds of it might calm down that vortex?

TBF, that's what I'm planning to do. I just need to figure out how much water is enough to keep things cool, and then come up with a way to dump off the excess.

Still seems bizarre that I am having to worry about this with a mild cam like I have. I ran these same headers on this engine with a similar cam, and did not see any obvious reversion. I do not recall seeing any rust on the exhaust ports when I tore that one down, and it ran for 30 hours. I think this cam probably gets the valve up off the seat more quickly, and coupled with the more efficient exhaust port creates a "perfect storm" for reversion. I also want to see if adding a reversion dam in the main header body will help things.

Auto Zone. 8 pieces of flexible exhaust tubing. Hole saw. Warning to passengers those are not hand holds sticking out of sun pad. Done! :stooges:

Budboy - I just PM'd you with my phone #. I'm on lunch for a few.

OK, I think SB and I have a handle on the situation. Nice talking to you Scott - thanks for the help!

Does anyone have Dr kevorkians cell number ?

You funny MT! :lolhit::stooges:

This past year it appears his # get's forwarded to mine.

Give me a call and I will end it for you for a small fee......whatever it is you want ended. I've been very busy doing this lately.

I might have to get in line the way this build has been going. :crazy:

You have already called, the bill has already been sent.

I have an antidote for my death syrum, for an extra fee.

On a serious note, hang in there. Many of us have been in your shoes. Schit, I had a damn engine take me almost 2 yrs because of schit like this - on top pf that getting married, moving, new business, etc, etc,etc.

It just makes you stronger and #1, when finally done it makes you enjoy it that much more.

Things like this make you realize why the big name builders get the $$$ they do. The ones that are cheap, well, don't work out to well.

Thanks SB. I went looking for some stainless 4" pipe like we discussed on the phone, and stumbled on an exhaust shop here in town that does a lot of custom stainless stuff. The guy who owns the business is a boater, and he took me out back to show me his Corsa (24x7 Pantera type) that has a 496 equipped with - you guessed it - Lightnings. So he is pretty familiar with my situation, and he has what is needed to help me get this sorted out. I have a couple of things I am going to try out this weekend, and I will probably be paying him a return visit on Monday to get everything done up right. Probably going to modify the existing tips as we discussed, but may also use the diverters with the butterflies removed and a long inner 4" pipe to extend the collector. I'm going to mock up one type of collector on each side and run it on the cart to see which one looks like the best solution.

He had a piece of stainless already bent on his expander that looked like it would make an effective reversion dam if welded to the inside of the 4" insert. What do you think, SB - would that hurt the exhaust flow too much?

http://i1224.photobucket.com/albums/...606_142050.jpg

http://i1224.photobucket.com/albums/...606_142118.jpg

http://i1224.photobucket.com/albums/...606_143027.jpg

If the stuff I'm trying this weekend doesn't work, he said we could just make a new set of collectors that are dry to the tip with just a single squirter angled at the tips and a bung for dumping the rest overboard.
I feel better now. ;)

I see what you got now. It looks like they should of had the water exit with the flow of the exaust instead of straight in to it. Like a baffle over those holes. I have CMI"s and the water flows with the exaust .They are like little channels insted of holes.

If you were going to make new pieces, heres what ya do.

Slip your new inner pipe, into the new outer pipe. On the side that faces the transom, you''ll see the distance between the inner and outer pipe to be 1/4'' gap all the way around (when inner pipe is centered). DO NOT seal/swedge/weld the pipes together at that point. What ya do is tack weld little 1/4" spacers, say 1/4x1/4, around the inner pipe at 4 points. Say 12, 3, 6, and 9 oclock position. This will hold the inner and outer pipe together, but leave the rest of the area open for water to flow directly towards the transom. Clean and simple.

try removing the drains completly out of the logs and see what that does...would be the same as my bleed-offs wide open...love to know

EZ, I think I tried that once before and it didn't make a lot of difference. There is just so much water going through those pipes that it would take a larger diameter bleed to make much difference. Did you notice any difference in sound level with yours open?

MT, I get what you are saying - would that be with 4 1/2 and 5" pipes? They used 5 inch outers and 4 inch inners to construct these, so there is about 1/2" gap in between. The 5 inch outer then funnels down to meet the 4 inch inner where the hose attaches, and that is where the water is introduced.

You 2 are on exact same wave length as me, and what I explained to him.

Group meeting adjorned. We have a game plan to go forth with. Go to it Budman. LOL.

no I did not, but what about a dump before the log to bleed off before the headers ? with what you are doing you can see how much water you can divert...

Ok ,so I have used the same headers with more cam...No problem. .Headers are not the problem with your build .You could just about have a gill type short riser exhaust on that cam and not have an issue. If it is truly sucking back hard, you did something wrong on motor..Did you degree the cam in.If so ,what timing set did you use ?........Never have I heard as much debate over a relatively mild build .......

Were you using the regular fixed collector Lightnings, or the ones with the rubber hose and divorced collectors like these? They are different in the way they introduce the water. Yes, cam was degreed, and set straight up according to the instructions. I would have to look up the brand on the timing set, but it had the multiple keyway crank gear. I don't know if it's as much a factor with the cam as it is the direction and amount of water flowing out of the headers. I think the improved breathing of the heads might also actually be acting against me on the reversion - just as easy for it to flow back as it is to flow out. I agree that it is pretty bizarre that I am having to spend this kind of time fixing this. Engine made 585 HP and 605 ft/lbs - if something was really wrong with it, don't know how it could produce those numbers.

Thought that running a 20* module and advancing the cam to 14* might help a little, but it's splitting hairs.

Same headers ..what you are calling divorced collector ..I think they called them extended aft water when I bought them .Only difference in motors being rpm airgap intakes because they were on a 39' stinger. AFR 305 heads

Low water exits through the transom or regular height? Asking because the drop has a lot to do with it, as 'm sure you know.

FWIW, my friend is running (I think) the same headers with an HP500 carb cam. Who knows? :o You brought up a valid point that something timing related could cause it to revert, but I'm pretty sure it's put together right. Thanks for the input, motor.

I know you gave cam specs, but who's cam ? as I stated in another thread you can change or "fool" the engine a lot by moving things around and still keeping the same lift/duration...example, you can add or remove compression with the cam design, now won't be computed figure like a 125cc dome with 130cc head, but ck with a compression gauge and can change a bunch...both ways

EZ, it is one of Bob's cams, but he did not grind it for this specific engine. He ground it for another OSO member, whom I bought it from. It had never been run in an engine when I got it. He actually had two identical cams ground and only used one. It was ground specifically for a 502 with stock 088 heads, RPM Airgap, and Stainless Marine exhaust. I looked at the specs and thought it would be an ideal cam for what I was planning to build at the time, as I was going with the same heads and induction back then. Then later on I switched to the AFR heads and Dart single plane. In numerous conversations Bob had mentioned that this may not be a suitable cam with SC. He said you have to be careful comparing specs between cams, especially a roller to a flat tappet, because a roller gets the valve up off the seat faster and there can be a lot more area under the curve where the valve is off the seat. If I had planned this project out with Bob from the start instead of backing into it like I did, I'm sure that he would have designed me a cam that worked with my combination from the get-go. As it is, I think my real problem is the way the water is going into the pipes, and that is how I plan to deal with it for now.

Just as a hypothetical, what effect would advancing or retarding a cam have on reversion? SB, MT, others want to weigh in? Just curious.

Merc Blue has their Crane Cams installed 5° advance in the HP500/500EFI/525EFI for a reason. Closes the exhaust valve sooner. A wider lobe seperation angle (LSA) closes the exhaust valve sooner also.

Remember, the exhaust valve is still closing After Top Dead Center (piston going down) on the intake stroke.

Atmospheric pressure doesn't care what valve is open, just as long as it's open. It tries to fill the growing void left by the piston going down. So...air/exhaust/water coming back thru the exhaust into the combustion chamber is exhaust reversion.

good explination sb.timing events can cause or lessen reversion.maybe your post will help some understand that.

Longer connecting rod"s help prevent reversion also.

Ran it again, with one side having the regular tip with restricted top water holes, and the other side having the silent choice diverters with a 4" extension pipe cut at an angle to extend the dry part of the exhaust almost all the way to the butterfly. This allows most of the water to drain right down the Y-pipe, with a little bit going out the tips. Ran it and both sides were pretty wet. Damn. So I ran it with the seawater pump belt removed an no water coming out the exhaust. Held a thin piece of paper at the tip and observed it being shredded as it pulsed back and forth. Put my hand back there and it was sucking it back pretty hard. I had visions of "motor" yelling "told ya so". Then I had an idea, and almost on a whim, put both muffler tips with the salisbury flappers on there and ran it for about 45 seconds. Boom - both sides dry as a bone. Ran it again and pulled the headers - pipes still dry. Can it be something as simple as that? SB, your earlier quote about collector length versus primary length is going through my head. Or was it just a matter of the salisbury flappers dampening the back pulse?

The flappers don't dampen the pulse per say, they try to stop it. Positive pressure opens them, there no pressure or negative pressure closes them.

Remember, they are there to close down when engine not running and/or wave hitting back trying to go into the pipes.

The closing isn't as quick as the reverse pulse, but they do help.

So, in this regard, ie: trying to close when 0 or negative pressure, I guess they do dampen...but more the return energy wave..as it's trying to be a one way valve of sorts.

What I mentioned earlier was about collectors dealing with energy waves. Exhaust physics show that as an energy wave 'hits' the atmosphere, there is a resultant opposite wave that shoots back.

Camshaft and exhaust designers try to make it so your exhaust valve is closed, or almost closed, when this happens. It appears exhaust is more important in this regard.

A wrong collector length can ruin your day.

Again, if your header collectors are 4" and the rest of your exhaust is 4", then the rest of the exhaust count's as part of the collector.

I'm at work and trying to get out of here, so excuse me if my typing and 'talking' or lacking. LOL.

FYI: I've never run or tested without flappers, so I never thought about it ...at all.

Learn something new everyday...thanks....

Edit in: and yes, mufflers can effect your 'tuning lengths and etc' also.

SB, thanks for the reply in the middle of a busy day. Sucks having to work on a Saturday. Hope you enjoy the rest of your weekend.

I'm dropping it in tomorrow. Going to play with it a little more this evening, and decide which collector to use. Gotta say the silent choice ones with the 4" extension pipe running through them are looking pretty promising.

My 525, which has a "bigger" cam, has been running fine for years with the CMIs and silent choice diverters and 4" tips with internal flappers. The Y pipes are kind of a safety feature if any water gets past the flappers since it will run down the Y pipe instead of going over the hump.

a misadjusted rocker will cause reversion..like i stated eariler i would not like the angle of the holes the water is coming out of..my gils were like that and i changed them and now the water exits towards the rear and no reversion..

Bud, what did you put the cam in at?

Cam was installed straight up. According to the cam card, the exhaust valve closes "-3.2* ATDC". So I guess this means it closes 3.2* BTDC, right?

Just as a note, that must be timing at .050" lifter rise. Seat (,004" or .006" depending on manufacturer) will be always be ATDC.

Look at cam card again and post what the LSA, ECL and ICL is. This will tell us if the cam , if installed per card, is advanced or not.

Actually, forget that. Give us all the specs and tell us how you installed it (degree wheel and where you set to or just dot to dot) and we'll tell you if advanced or neutral or retarded.

The more u advance it the less it will revert. When the chain stretches it will advance a couple degrees. I usually install mine a little retarded for that reason but don't have water in exhaust problems as you do...

yes, advancing the cam would help...the flappers also work like a check valve of sorts to help as well..

You are correct - the numbers I listed from the card are at .050, so I guess the valve can actually be off its seat a lot sooner than that. I do know that this cam gets the valve open in a hurry. I don't have any numbers at .004 or .006.

Intake centerline is 110* ATDC, and exhaust CL is 118* BTDC. I'm far from an expert but I think that means the cam will be 4* advanced when installed "straight up". That's the way I did it - dot to dot, put a degree wheel, established true TDC with a pointer, and verified that the valve events with the wheel and a dial indicator. Also, the cam card says to install it "* *", which I would take to mean straight up.

Bob doesn't generally want to have the full specs for his cam posted on the web, and I can understand him wanting to protect his intellectual property. He has helped me out lot, so out of respect for him, I don't want to post the full specs out here on the WWW.