Offshoreonly.com - Exhaust Help

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You might want to look at some gill wedges or have some wedges custom made to correct your alignment issues.

Quote:

Originally Posted by Derrick (Post 4627522)

that was the absolute last thing you wanted to do...

Agreed.

You could send the risers back to EMI and they can make them 3" taller. Making a taller riser would correct the issue and return the correct amount of "fall" to the system.

If you can't find what you're looking for, for sale off the shelf I can make you whatever you need. I own a small machine shop...

Either way I wouldn't run those risers now that you cut the flange off of them.

Actually I even have a set of Gil risers I could sell you pretty cheap too. Not sure if they would work on that Emi manifolds though

So EMI makes a 3" taller set of risers. Went ahead and ordered them yesterday. Hopefully they will work.
Live and learn right ?

Best move buying 3 inch taller riser. Did you get the long riser 16 inch ?

Quote:

Originally Posted by jryotas (Post 4627487)

https://cimg7.ibsrv.net/gimg/www.off...cafd4fbd5e.jpg

was that hole on the top or the bottom? almost looks like the flange you cut off was wearing its way through the rubber from vibration and misalignment. cant tell if that's burnt rubber or carbon build up

Quote:

Originally Posted by KeatonAZ (Post 4627669)

Well , best I can tell it burned through due to mis-alignment and the fact that the exhaust gasses were basically dumping downward onto the tubes with little room for cooling to happen.

I even started to burn through a set of the silicone tubes before I cut the beveled part of the risers off . The exhaust gasses are obviously really fukin hot !

Hopefully the new taller risers will fix this issue. Im still not sure though how taller risers cuts down on reversion. Maybe just harder for the engine to draw water up that much higher ?

Quote:

Originally Posted by jryotas (Post 4627670)

Yes taller risers have a steeper angle which does make it more difficult for the water to get sucked back up in. But at least on my Gil risers having a 3in taller Riser does not change the exit point. I have standard Gill dry to the tip offshore risers and 3in taller dry Gil risers. Both have the same exit Point by the time you get to the transom...

in other words 3 inch taller + steeper angle = same exit point

Quote:

Originally Posted by jryotas (Post 4627485)

So I installed a set of emi manifolds and risers on my gen vi 502 mag mpi. Had some alignment issues and I kept burning up exhaust tubes due to the exhaust gasses exiting pointed at the wall of the tubes , not out the back of the boat. Even tried the high $ silicone tubes . Finally ended up running an extra piece of stainless between the riser and tips in the transom. I also ended up cutting the flange off the risers to help correct the angle issue, about .5" was cut off . Im a lil worried about reversion. I assume that is the reason for the flange on the end of the risers?

So now im not burning up exhaust tubes but am now noticing a miss if I idle for more than a couple minutes. The miss goes away of I rev up a little. Should I have a muffler shop add a lil flange to the end of my risers? I have replaced the spark plugs and there was no signs of water.
I would post pics but seem to have not hit my 10th post yet ):

How tall qhere the blocks in between the stock manifold and riser ?