View Full Version : Dumb Question of the Day...which risers/manifolds?

12-20-2011, 10:17 PM
those of you that saw my pictures in my 454 rebuild post know that I'll be needing new risers and manifolds for my recently aquired 454 KC '93 Classic 22. So anyone care to weigh in on what a good replacement exhaust might be? I plan on going to closed cooling when I either rebuild so I'll need some advice on a good kit there too.

Thanks Again.


12-20-2011, 10:36 PM
J Z~

For nice Fresh Water Cooling bolt-on systems check-out Montor Products .
I have had one of their bolt-on engine mounted kits on my 454 Indmar engine/ skiboat since it was new with no issues.
It works great.

They sell both 1/2 systems & full FWC systems that include the exhaust manifolds also.

12-20-2011, 10:43 PM
Thanks Brad I'll check it out. ...so much to learn on this project this is really new to me. Thanks for the advice.

12-21-2011, 12:19 AM
Check E-Bay for manifolds. etc as there is a GLM dealer in FL that is real cheap. Get the Alum for a great price and they will bolt up to your FWC system. Also if not going crazy HP the OEM Mercruiser SS risers are pretty cheap and my friend has NOS set for I think $300.

12-21-2011, 08:01 AM
The OMC boats sometimes had funky exhaust exits just make sure the new risers won't need special plumbing or glass work

12-21-2011, 08:55 AM
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Mattyboy, How do I determine if I have the "funky" exhaust exits? ...not totally opposed to glass work but if I can avoid it that would be best.


12-21-2011, 09:27 AM
the OMC boats I have seen with the funky exits are either really wide near the gunwales or really narrow right over the drive, you would notice some creative plumbing in the bilge. If that is not the case and the old motor had just hose from the riser to the tips with no 45s or 90s elbows you should be ok.

12-21-2011, 09:39 AM
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Looks like I have the normal exhaust as it is just a straight shot from the manifold to the thru-hull exhaust via a straight rubber coupler.

I'm kind of leaning towards building a mild hot-rod power plant and I know good exhaust counts... any thoughts on where to look? ...kind of thinking about somethng lighter than what came off if possible. ...aluminum? stainless?

I weighed the old mill when it came of ouf the boat. I had already removed the exhaust manifolds and the thing weighed in at 940 lbs. for what it is worth if memory serves the boat weighed 2200 lbs without the engine, drive or engine cover hatch.


12-21-2011, 09:45 AM
the OMC package 22 boats had a more centered location exit and a tad higher than the previous or later boats

quite frankly, I liked it, I had one

they had SS doglegs to connect from the riser to the transom outlets

I would absolutely leave it that way if it was me

the OMC package 18 boats had them a little lower and farther outboard than previous or later Merc boats

12-21-2011, 12:24 PM
Wait a minute - your 454 KC was 940 lbs WITHOUT manifolds and risers?

Heavier than I thought. I would have said 1000 lbs WITH the exhaust.

I'd guess you had a good 100 lbs in in the stock cast iron exhaust. Likely more.

12-21-2011, 12:25 PM
Oh, and for what it's worth, I like the Stainless Marine aluminum manifolds with s/s risers...

12-21-2011, 02:27 PM
A 454 with the transom assembly and Bravo drive is roughly 1180lbs complete with exhaust.

12-21-2011, 02:52 PM
One more for Stainless Marine, they last like no other performance manifold. As for closed cooling systems, I've had great results with Orca, http://www.orcamarine.com/news.html

Good luck,