Mr Gadgets

dgood,
Do yourself a favor and just modify the tail pipes. I had the same problem when I built a 502 yrs ago. I ened up extending the inner pipe by 1.5"-2" and the problem stopped. At idle I could see the water climbing up the ID of the exhaust pipe. I had a solid roller cam in it. Not sure what it was. But those three little holes in the inner pipe introduce the water into the exhaust stream and bingo.. reversion.
I cut the outer pipes and then extended the inner one, put a ring aound it with three grooves (2-6-10 oclock). Used a piece of rod the size of the difference between the inner and outer pipe. The two pipes can grow at different rates so you dont want to weld the inner to the outer.
That would solve a reversion problem.. not the easiest, but it is final. Find someone in your area that can weld SS and go for it..

Hope this helps.
Dick

Young Performance

I could not agree more with Dick (mr. Gadgets). Extend the pipes a little and solve the problem.
That cam with 238* exhaust duration nsounds a little big for that exhaust. I have seen the exact problem that you are having....one engine reverts and one does not. We lenthened the risers and the problem went away. I would bet good money that you have a reversion problem. I can not explain why one would do it and not the other. I quit trying to figure it out and just fixed it Good luck.
Eddie

ezstriper

even with two idenical engines...they rarely are, theres always differnces here and there, the way the cams are ground, how far a valve is in the seat from a valve job, timing, carb adj and idle speed....all could effect it if you are on the edge....Rob

Young Performance

Certainly. Depending on the exhaust, some do not have equal risers because of the offset of the engine. There are just to many factors....just like what was listed above. Just a half an inch in where the water enters the exhaust could be all the difference needed if you are on the edge. I think the cam is to big at 238 deg. to use with that exhaust. It doesn't really come as a surprise to me that it reverts. I'm surprised that both engines aren't doing it. Like was said, a little extension to the pipes should fix it.
Eddie

dgoodman

Thanks everyone for your input. I will try as suggested and update the post.

dgoodman

Just came from the machine shop and with the intake off saw signs of water (IE rusty) in the aft intake ports on both sides. Is it possible for reversion to suck into the intake side of the head??? Doesn't make sense does it?.

Mr Gadgets

When I found the problem, I fixed it before rust could occur, on the engine test stand. I wouldnt think it would get to an intake port. Maybe someone else can share their experience.
If you have excessive water psi in the block, it could have damaged the intake gasket??? Any signs of that?

DORaymond

I have had a bent exhaust valve (obviously not sealing) and found that water was pulled into and puddled in the MPI intake plenum. Of course, I new I had a problem because the engine was missing.

Smoothsix

How does the reversion put water in the oil ?

PJDiesel

A few ways.

1) leak down after shut down (past rings over time).