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Finally satisfied
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Discussion Starter #1
Here is the situation. I have a new motor its a 638" bbc, dart block, intake and heads. the headers are cmi split tops. the cam is from comp but it was a teage specific cam. the specs on the cam are 258* intake 266* exhaust* @.050" on a 114 lobe seperation. the headers have no drop at the tail pipes and the are injected at the tips. I used these headers on my other motor and they were fine. the problem is is that I keep mixing water and oil. I pressure checked the block it checks out ok so at 40 psi I have no loss of pressure. the headers check out ok at 35 psi but the 1,3,5,7 cylinder side of the motor has water in all 4 header tubes after running it at idle for a few minutes. its about a tea spoon in each tube.:mad: there is no water in the other header. I am not sure that the water in the oil is coming from the exhaust but why would only one side of the motor have reversion? the tail pipe on this side is the longer of the 2 if that matters. HELP!!!!! I am out of ideas and patience. I have ran the motor with the oil cool rbypassed and it does the same thing. even though the cooling system and the leak down check out ok couldnt the head gasket still be pushing water????????? I am about to go through a divorce over this lol.
 

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Boat Nut
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bypass the water in the tail pipe, dump it over board, to test the reversion theory. If no water then you have your answer.
 

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Discussion Starter #4 (Edited)
the leak down was 3 to 5% across all 8 cylinders. the compression test shows 170-180#s. I did dump the water overboard this afternoon and it still has water in the oil. I pulled the intake and it is concentrated at the front corners of the intake to the point that it looks like an actual milkshake. its very thick in the 2 corners. I cant see why a pressure test wouldn't reveal an intake leak but I believe thats what it is. I also pulled the heads off and the head bolts were no longer torqued to what I had them. I believe that the head bolts may be a little long they are arp bolts but the dart block has blind holes. I am thinking that the heads will torque when the cometics are new but when the settle in I believe that the head bolts are bottoming out before I can get crush on the gaskets. I ordered new cometics, new intake gaskets and new head bolts that are specific to the dart heads. whats different about the bolts I dont know but they are different. my theory as simple as it may sound is that the heads are lifting allowing the compression to push water into the front corner of the intake. sound plausible? The reason I think this is because it doesn't present itself when checking with psi it only does it when its running. 170-180 pounds of cylinder pressure its certainly enough to push water out of a non seated gasket I think???? thanks for all the input guys.I am about to throw in the towel lol. I am over 15k into this new motor and its never been in the water.
 

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The head gasket does not settle in as much as you think. Try installing the head bolts without a washer to see if they are too long. Then put the washer back on. I had this same exact thing happen to me a couple years ago. Would only put a small amont of water in the engine, loaded. Block would hold 100 psi for hours and passed 2 mag checks. Ran the whole series of checks you have done without any concrete results. On the 3rd tear down with a season on the engine (30-35hrs) I could see a discoloration on the cylinder wall about 2 inches long, from bottom to top of bore. Remember this thing would hold 100 psi ! And passed mag. End result, fractured cyl. wall. Was there from day 1! What a looser engine job that was.
 

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That quality of a motor should have head studs anyway. I would say switch to studs - which would insure that you are not bottoming. I am sure the bottom end has studs, so the drapes would match the carpet! :)
 

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Discussion Starter #7
There really isnt any need to run heads studs on a pump gas n/a motor in my opinion but I may go heaed and do the head studs anyway. as far as a cracked block this thing is brand new so I wouldnt THINK that that would be the case but................ since the milkshake is concentraded at the front corners of the head and intake I am going to try to start there.
 

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That quality of a motor should have head studs anyway. I would say switch to studs - which would insure that you are not bottoming. I am sure the bottom end has studs, so the drapes would match the carpet! :)
finding carpet is pretty rare...
 

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first x2 on the headstuds,
this happened to me some 30 years ago,bbc kept mixing water into the oil and i fought it for about a month doing all the test and gasket changes and a barrel of oil, my last ditch effort was a product called liquid glass i put it in a five gallon bucket and ran thru the motor only for about a half hour just cycling thru motor shut the motor off and drain and let system air dry and it fixed it. it was in a v-drive

as for the real cause that i found years later is machine shop guru pushed the guides out the wrong way and damaged the heads,exhaust guides are water cooled.
 

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Same problem, Solved.

New BBC 565, AFR heads and Lightning headers.
My mechanic pulled the heads twice, we sent headers to Lightning for testing, nothing cured the problem. I switched to Cometic head gaskets
#C-5331 and Felpro intake Gaskets #1275. My problem was gone. I was told that some gaskets do not properly cover water, oil and compression areas. I am not sure if these gasket are the ones for your motor. C Straub is on this forum, a lot. He helped me and I would recommend him to you. Good luck.
 

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Discussion Starter #12
New BBC 565, AFR heads and Lightning headers.
My mechanic pulled the heads twice, we sent headers to Lightning for testing, nothing cured the problem. I switched to Cometic head gaskets
#C-5331 and Felpro intake Gaskets #1275. My problem was gone. I was told that some gaskets do not properly cover water, oil and compression areas. I am not sure if these gasket are the ones for your motor. C Straub is on this forum, a lot. He helped me and I would recommend him to you. Good luck.
thats the same head gaskets that I am running. I am replacing them this week and also trying a thicker intake gasket. My concern now is why the head bolts were no longer torqued after a few heat cycles? the funny thing is if this wasn't my motor I would have it fixed by now. since I have so much money in it I keep second guessing myself. I did use the arp head bolts out of my other motor and I am now thinking that was a bad idea. I have new head bolts going in also.
 

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Boat Nut
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Be sure to torque them with the ARP moly, and not just plain ole' motor oil.
 

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On a bbc I ALWAYS torque them with thread sealer. You can get stuff at home depo for plumbing that has an oil in it. If you need I can dig up the name for you.
 

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Here is the situation. the headers check out ok at 35 psi but the 1,3,5,7 cylinder side of the motor has water in all 4 header tubes after running it at idle for a few minutes. its about a tea spoon in each tube.:mad: there is no water in the other header.
There should be no water in the tubes.

With any water entering the exhaust, the exhaust should have a good downward slope. The more the angle of the slope, the better. This is why you typically only see system like yours run full dry. The wet systems (water entering the exhaust stream) on boats like yours with big motors will usually have the tails mounted much lower on the transom using a steep bend 'S' pipe sort of connection or tail.

Bigger cubes draw in more air thru the exhaust then smaller cubes. More cam overlap draws in more air thru the exhaust. Etc, etc. Air coming back into exhaust pulls in water if it's stronger than the gravity effecting the water.

Higher idle speed also helps fight reversion. What does yours idle at? Ignition timing can too. What's your base timing ?

Hard to guess if you have an intake/head leak / or etc, but I can tell you that any water in the exhaust ports is no good and that you either have an exhaust water leak or a reversion issue. If you can run the tails dry for a few and you see no water getting into the engine, the straight tails is your 'smoking gun.' You'll need to make these dry (still water jacketed of course) or get some that are at a steep angle down. If noise is an issue with completely dry tails, you could add some mufflers.
 

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Here are some quotes of myself from other reversion threads. Hopefully this helps.

Yes, the water can/ will flow backwards.

Been proven thousands of times in I/O applications. It's a very real issue ! Has even happened to OEM's !

Think wet exhaust where water enters in the exhaust stream. Many people, even with aftermarket exhausts, after building more performance will run into this....even trying to build around exhaust water reversion. One must then make the exhaust tubing have a greater rate of fall and/or introduce the water later, and/or change exhaust manifold or header system to a different style, and or ......................

You can literally stand behind the boat and watch water flowing back up the tailpipe.

So, anybody running a I/O type exhaust (examples but not limited to Imco, Gil, Stainless Marine, CMI, etc,etc,etc) that just built a new higher performance motor must absolutely pull and check the manifolds or headers at the head flange for signs of water !!!! If you find water down there we must do something before something goes Boom !

You jet boaters/ v -drive guys with no engine hatches get to run differrent exhaust headers/manifolds then we do. Yeh, they can present there own different issues depending on design but typically they can handle much more cam ie: overlap than what us I/O people can run.

Side note speaking of exhaust reversion - Wideband 02 sensors ! Say if trying to set your idle A/F ratios and no matter what you do the wideband shows a lean mixture you could possibly be running into enough exhaust reversion that the air (oxygen) flowing from atmosphere thru tailpipes into rest of exhaust and past your wideband sensor is giving you a 'false' reading. This is very real especially on long duration cams and/or wideband sensors located too close to the atmosphere.

Why reversion ? IVO happens before TDC as piston is going up. This starts to push combustion gases up into intake manifold. EVC does not happen until after TDC when piston is going back down. Therefore you have IV open and lifting higher and you have exhaust valve open and closing. Your intake manifold has vacuum and your exhaust is open to the atmosphere. IE: Your exhaust valve connects to the atmosphere also ! Remember, our atmosphere has psi. Adding in a physics rule that high pressure will always go towards low pressure (if physically connected of course) . Definition of vacuum is psi that's lower than atmospheric. The slower an engine is running the more time (in seconds for a given cam duration) is available for these things to happen. To picture this - imagine valves opening and closing at 300 times each at 600rpm. Now, imagine them at 600times each at 1200rpm. Huge difference in time available for each event and for air/exhaust to actually travel in 'wrong' direction.

Sorry for rambling. It's just a sore subject that needs to be (and is) talked about in wet exhaust systems and especially those that have to follow noise guidelines.

To answer your above question: Looks can be deceiving. Many 'dry' systems have the water enter at the very end of the tailpipe - ie: tube inside the tailpipe dumping the water just at or just past the end of the tip.

To further go on about exhausts and such:

Their are 3 main types of exhaust and many variations of each.

Transom tip: the exhaust tips are seperate from the tailpipes. Thus the water in the outerwall of the tailpipes must enter the exhaust before the rubber hose connecting the two of them. This places the entry of water closer to engine and makes for more sounds absorption, but easier to revert. This is the quitest of the 3 types.

Thru hull - the tailpipes continue right thru the transom. This gives you more distance from the engine to dump the cooling water into the exhaust stream. Again, further away you introduce the water, the less chance of reversion. These are noiser than above because of the exhaust travels further before water is introduced.

Dry - same as above but the water is not introduced into the exhaust in the tailpipe. Again, Many 'dry' systems have the water enter at the very end of the tailpipe - ie: tube inside the tailpipe dumping the water just at or just past the end of the tip. Others will have use a thru hull fitting to dump water and some will have a fitting on top of the end of tailpipe pointed in another direction than the exhaust is going in the atmosphere. This system removes most or all (depending on where you 'shoot' the water) of water reversion chance but comes with a steep price to pay, not just $$$, but noise.

With exhausts, the greater the rate of fall and the farther (edit in: 'away') you introduce water to the exhaust gases, the harder it is for a motor to revert water.

Unfortunately, the further you enter the water into the exhaust stream the louder the exhaust is. Also, the more expensive the exhaust is. Double wall stainless pipes are much more expensive than single wall.

Many boats don't have enough room (hatch to waterline) to provide a real good rate of fall. Some do, but not many. Boat manufacturer tip placement for most boats is typically put at the standard 'Bravo' location which provides enough rate of fall for Merc engine packages that come in front of a Bravo.

So, there you have it. As you know the more overlap a cam has and/or the lower it idles (Bravos under 1,000rpm, Alpha's under 800rpm, crash box or drives that have no shiftable mechanism in the drive and use a transmission instead can usually tolerate more idle rpm. Crash boxes are shifted when engines are turned off.)
 

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I have found that new head bolts and studs also will slightly stretch after the first few heat cycles and then need a retorque.
 

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Discussion Starter #18
There should be no water in the tubes.

With any water entering the exhaust, the exhaust should have a good downward slope. The more the angle of the slope, the better. This is why you typically only see system like yours run full dry. The wet systems (water entering the exhaust stream) on boats like yours with big motors will usually have the tails mounted much lower on the transom using a steep bend 'S' pipe sort of connection or tail.

Bigger cubes draw in more air thru the exhaust then smaller cubes. More cam overlap draws in more air thru the exhaust. Etc, etc. Air coming back into exhaust pulls in water if it's stronger than the gravity effecting the water.

Higher idle speed also helps fight reversion. What does yours idle at? Ignition timing can too. What's your base timing ?

Hard to guess if you have an intake/head leak / or etc, but I can tell you that any water in the exhaust ports is no good and that you either have an exhaust water leak or a reversion issue. If you can run the tails dry for a few and you see no water getting into the engine, the straight tails is your 'smoking gun.' You'll need to make these dry (still water jacketed of course) or get some that are at a steep angle down. If noise is an issue with completely dry tails, you could add some mufflers.
the headers were on my other motor which was the same basic combo just 8 cubic inches less for 8 years? the motor idles at 1100 or so rpms. the timing is at 36* I did run the motor with the water dumping over the sides and the oil still milked. I personally do not see how the motor wouldn't hydraulic if water was getting into the combustion chambers as the leak down is 3 to 5 percent across all 8 cylinders. can that much water get past the rings? we are talking about 1 quart of water in just a few minutes. btw thanks for the info guys.
 

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I run a 268/274 solid roller cam at .050, with a .715" lift. I run Lightning double jacketed Headers with full time water.
Everyone kept telling me my milkshake was due to reversion. It was NOT.
I cannot tell you if my head gaskets were leaking or if my intake gaskets was leaking. I can tell you that changing them CURED the problem.
A double jacketed header does not induce water into the exhaust untill the last few inches. If you are using something else, don't listen to me. I can only speak for what I have and what WORKED for me. Ask C. Straub for advice. He knows his sh-t. Good luck.
 

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Discussion Starter #20
I run a 268/274 solid roller cam at .050, with a .715" lift. I run Lightning double jacketed Headers with full time water.
Everyone kept telling me my milkshake was due to reversion. It was NOT.
I cannot tell you if my head gaskets were leaking or if my intake gaskets was leaking. I can tell you that changing them CURED the problem.
A double jacketed header does not induce water into the exhaust untill the last few inches. If you are using something else, don't listen to me. I can only speak for what I have and what WORKED for me. Ask C. Straub for advice. He knows his sh-t. Good luck.
the headers that I have introduce water at the tip of the tail pipe. I am taking the heads in the morning to have both of them psi checked before I put it back together again. I hope that my head bolts being a little loose is the culprit.
 
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