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Reversion - Should I be worried?

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Reversion - Should I be worried?

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Old 03-25-2019, 07:52 AM
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Default Reversion - Should I be worried?

I have read a few threads recently about guys having issues with sucking water back up through exhaust even when dry to the tip. I hope to get this thing going this summer (finally) and don't want to destroy these new motors before it even gets wet.

My setup has 652HP, 427cid Small Block Chevy motors with Lightning headers with 2+ foot tail pipes that are dry all the way to the tip. When designing the build, I was thinking dry to the tip eliminates reversion possibilities but again, seeing some recent threads makes me a little concerned. My cam specs are as follows:
  • Intake lift .600
  • Intake duration 296
  • Exhaust lift .600
  • Exhaust duration 302
  • Lobe Center 112
  • Intake C/L 108
Any suggestions on first start? Run it for a few mins, pull the plugs and look for what? Other thoughts?
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Old 03-25-2019, 04:44 PM
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run it and pull the headers after idling for a while. you may be able to see the reversion, but i bet youll be ok. that a decent cam. but you also have prettty decent cubic inch.
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Old 03-25-2019, 07:49 PM
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Originally Posted by beaver 3 View Post
run it and pull the headers after idling for a while. you may be able to see the reversion, but i bet youll be ok. that a decent cam. but you also have prettty decent cubic inch.
Will I just see water droplets in headers?
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Old 03-25-2019, 08:01 PM
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Like he said, just run it and check it. Be easier to pull plugs first and look for moisture. I've got stock 502 mpi mag with only Eddie Marine exhaust and have had severe reversion since day one. I've tried everything from heating up manifolds, elbows with engine circulating water, to timing, to exhaust anti-reversion plates under the elbows, to Mercury resonator plastic anti-reversion inserts, you name it. Very hard on valves, especially in brackish water.

I finally solved it completely. Had to add extensions on the elbows. Welded 3" alum pipe to the end of the elbow tubes all the way behind the transom. First added about a foot. Then added to the transom, then about 6 inches behind the transom. That's when it all stopped. You can't do that on headers though.

I just held a piece of vinyl over the end of the exhaust, and you'll be able to see if its sucking back. If it pulls the vinyl in and out pretty bad an inch or two, chances are your having reversion also. It's killed a set of heads on mine before i put enough effort in to solve it. .I've seen many a peeps with high dollar high HP motors and just couldn't hardly stop the reversion with headers. Sometimes with the water not mixing until the end of the exhaust. Some had to go completely dry and run the water out a separate fitting on the transom. Fortunately mine are elbow type exhaust and i could do something about it. Good luck.
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Old 03-25-2019, 08:16 PM
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I have not heard of anyone having reversion problems running dry to the tip headers. I have a huge solid roller cam in my 598 and have no reversion.
You can get condensation inside the headers IF the headers are cold.
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Old 03-25-2019, 08:50 PM
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Thanks for the responses. I think I’ll fire them and chk plugs as a starting point. I like the vinyl idea to see if it is sucking back.

im definitely not trying to have a problem, just want to make sure if I do I catch it before I break stuff.
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Old 03-25-2019, 09:59 PM
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Do you have bungs on your headers for O2 sensors?
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Old 03-25-2019, 10:29 PM
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Originally Posted by Baja Rooster View Post
Do you have bungs on your headers for O2 sensors?
no o2 bungs.
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Old 03-25-2019, 11:30 PM
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ttrm007 Yes You'll see either water droplets if you look quick enough. If its dry inside, it shoud be little whitish specs
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Old 03-27-2019, 01:50 AM
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Any water drops in Lightning Headers will most likely evaporate before you can get the header removed.
Reversion happens at idle. If the idle quality decreases on long idles, it COULD be caused by reversion.
Looking at you cam specs, I really don't think you'll have any issues.

I assume your advertised duration is about 236/244 and its a 112 lobe sep.???
That is only 16* of overlap so you should not have any issues. Camshaft Overlap Calculator - Wallace Racing
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