How important is the Exhaust seal flapper?

[HT32BSX115]

Yes it is.

If you don't have spare exhaust manifolds, do you have a plan for replacements?
I don't think there's anybody making them anymore. This was the main reason I R&R'd my 460

 

[Trevthefox]

If you don't have spare exhaust manifolds, do you have a plan for replacements?
I don't think there's anybody making them anymore. This was the main reason I R&R'd my 460

No plan yet. I pretty much got this boat for for pennies. The risers and manifolds were a little clogged (not too bad). I think when it comes to that time I'll re-evaluate whether I want to:
1) Sell the boat
2) Replace manifolds and risers with aftermarket replacements/adapters (http://www.manifoldwarehouse.com/mes/mgr?brch=mesprod&pno=hge-460kclr)
3)Re-power with 454 Mercruiser

I just hope I can get a couple seasons out of what I have right now. It's been a love/hate relationship working on and learning about the OMC's.

 

[HT32BSX115]

No plan yet. I pretty much got this boat for for pennies. The risers and manifolds were a little clogged (not too bad). I think when it comes to that time I'll re-evaluate whether I want to:
1) Sell the boat
2) Replace manifolds and risers with aftermarket replacements/adapters (http://www.manifoldwarehouse.com/mes/mgr?brch=mesprod&pno=hge-460kclr)
3)Re-power with 454 Mercruiser

I just hope I can get a couple seasons out of what I have right now. It's been a love/hate relationship working on and learning about the OMC's.

Yeah....It's a real education!

I tried to buy those when I looked and they told me that they weren't available. Maybe they really are now.....My only choice back then was Stainless Marine. (about $3000 for manifolds/risers)

Also at the time, there were no coupler either but I hear that Sierra has a 460 coupler now available at any dealer that sells Sierra. That was a real show stopper.

You can also pretty much get your drive rebuilt by a few rebuild companies now too although there are some parts like the vertical shaft that are not available. There are used parts available and I did read about one guy that simply had a machine shop make one for him. He didn't say how much it cost him!!!

I pretty much needed to completely rebuild the engine and replace the manifolds so considering what that would cost, I didn't think it would be all that much more to just do a swap with a used engine/drive.

About the same time a guy up north of Seattle put his (120hr since new) 1997 454/Bravo III on Craigslist and I bought it. ($5K) ........He had a 1998 24' Bayliner Cuddy that had a tree fall across the bow and was parting it out.


Later, I was able to sell all my OMC King Kobra "stuff" piece by piece for about $3500 total, over a 3 year period. [I know! I REALLY lucked out!!] (I actually kept the OMC fuel filter and oil filter mounts to use on a truck project!!)

If you REALLY like the boat and it's in good condition, you might want to start looking now for a Big-Block (Mercruiser or Volvo powered) donor boat to buy for the future swap. That way you can have the engine and drive removed and hull gone for when you need it.....

If your boat is big and heavy, look for a Merc Bravo III or Volvo Penta Duo-Prop.....The difference in performance with the "same" HP is nothing less than spectacular.

Cheers,


Rick

 

[Lou C]

In salt water you usually get approx. 5-7 years out of the manifolds and elbows. You can test them by taking them off the boat and propping them up level. Then carefully fill the water passages with acetone (careful, very flammable) and let it sit. If you don't see any dampness or liquid in the exhaust ports that match up with the exhaust ports on the cyl head, they are still good. You can have the mating surfaces cleaned up by a machine shop or do it yourself with a belt sander (carefully) you want it flat and level to less than .003". Re-install with new gaskets and Permatex Aviation sealer for the elbow gaskets. None needed on the manifold to cyl head joint. I'm on the 3rd exhaust system on my boat. 1st 2 sets I installed were the OE OMC one piece batwings for the V6, these became NLA a long time ago, so I researched using the later style 2 piece exhaust that 91 and up OMCs and 94 and up Volvos used. I had to buy some V/P aluminum 90* exhaust pipes and hoses and was able to use Barr aftermarket manifolds and elbows. It all fit perfect and looks factory. Now for the next replacement I can use easy to find Barr aftermarket.