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-   -   tall deck to short deck exhaust problems (https://www.offshoreonly.com/forums/general-q/317794-tall-deck-short-deck-exhaust-problems.html)

bck 09-09-2014 12:18 PM

tall deck to short deck exhaust problems
 
So I went from tall decks to short decks thinking that slight difference wouldn't have much impact on the exhaust. Wrong. None of the CMI big tube tails fit anymore. Has anyone ever made an adapter plate to move the headers back closer to the tall deck position? Would it be possible? Any help/ suggestions would be great. I've talked to CMI and they aren't a whole lot of help.

Unlimited jd 09-09-2014 12:39 PM

Tips on the transom or dry tails that go through?

bck 09-09-2014 01:09 PM

Dry tails through and to make things worse it's staggered, so I've got issues where the front motors tail won't fit past the rear motors header now.

snapmorgan 09-09-2014 02:26 PM

I would think that you will have to have new tails made or possibly put on some heads with raised exhaust ports to make them work. Someone good with a mill could probably make you some adapters. but I bet they wouldn't be cheap or pretty.

bck 09-09-2014 02:57 PM

These are the old style big tubes, so they already have adapter plates. I was thinking a wedge type adapter to tilt the headers outward a little bit? Does anyone have a blueprint that would show the exact difference between a tall/short deck at the exhaust port?

Bawana 09-09-2014 03:35 PM


Originally Posted by bck (Post 4185616)
These are the old style big tubes, so they already have adapter plates. I was thinking a wedge type adapter to tilt the headers outward a little bit? Does anyone have a blueprint that would show the exact difference between a tall/short deck at the exhaust port?

Its 5/8 down & 5/8 in going from tall deck 10.2 to short deck 9.8. depending on the style of heads. If you have the old wrope seal headers its a easy fix. With the flex flair you can get adapter rings that CMI makes. If you wanna call me I can explane in more detail & send you in the right direction 920-475-0852

runninragged 09-09-2014 04:07 PM

cmi can mill exhaust flanges to use as a shim to angle the header in or out dont know if thats going to help though

bck 09-09-2014 04:54 PM

Bawana, is that a good number to send some pics to? I'll send a few showing what I'm working with then give you a call. I'm using AFR 315 heads on a 9.8, the previous heads were Brodix big brodies on a 10.2

Bawana 09-10-2014 02:00 AM


Originally Posted by bck (Post 4185669)
Bawana, is that a good number to send some pics to? I'll send a few showing what I'm working with then give you a call. I'm using AFR 315 heads on a 9.8, the previous heads were Brodix big brodies on a 10.2

yes text me pics & then call me


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