496 HO Manifold Replacement
 

Looking at a boat with 496 HO motors. Its a 2003 38 special. I would want to replace the manifolds. Are these the correct ones and what is the water rail conversion thing about?

Chris

Are what the correct ones? No link posted. there are many upgrades. whether of not they are any better is a matter of much disagreement. here are the oem ones. your risers, which have a very long life, will bolt right up. they are iron now. aluminum discontinued. Mercruiser New OEM Exhaust Manifold & Gasket Kit 8.1L, 496 MAG 8.1S HO 866178T01

gen 1 manifolds are NLA, the design and material changed.

The rail section is still available thou

Sorry guys.. Brain fart.. This is the link.
https://nuwavemarine.com/oem-mercrui...0aAo7fEALw_wcB

Chris

Any aftermarket ones any better for the same price or similar price. Not looking for performance gains. looking for longevity and if it adds bling too then thats a plus.

Chris

It is actually a quite decent manifold. An upgrade over the stock Mercruiser Center rise wet joint manifolds that date to mid 80's and use the same riser as v6 and 305 engines. Good to 550 or 600 hp before it starts getting in the way. And made by Gil, at least used to be so have a bit of OE bling. I assume you are changing exhausts cuz you don't trust 14 year old manifolds? Which risers are on the boat you are considering? I guess you don't wanna post the boat ad cuz somebody else may decide they want it?

I have no problem posting the boat. I have 2 boats already and need another boat like a hole in the head but it seemed like a good deal. If some else buys it then it will only save me money lol.
Used 2003 Baja 38 Special, Colchester, Vt - 05446 - BoatTrader.com
I just was wanting to research how much it was to replace exhaust if I decide to buy it. I had 24x7 years ago that blew a 496 due to a burned out internal flapper in the through transom exhaust. So a total exhaust replacement will be in the plans including internal and external flappers on any boat I buy. I currently own a 2452 Bayliner with a 5.0. I changed the exhaust as soon as I got it to merc dry joint style made by Barr and it is indestructible. 4 years in salt and still going. Don't ever plan on changing it again. When it blows I will repower with a 377. My other boat is a 2005 52 ft Cruisers 500 express with twin Volvo D12 675hp motors. It had the exhaust manifolds changed on it 1 year before I bought it . You should have seen the insurance agents face when they asked for boating experience and I told them I had a 25 ft bayliner...lol.. Anyway thanks for any info on the 496.
Chris

Early 496 exhaust had a water rail that mounted onto the manifold. Corrosion and leaks necessitated a redesign. Early manifolds were aluminum both styles. Later are cast iron. Your link shows the new style manifold. That kit contains everything to change over from water rail style to new style. Being an 03 it probably does not have the water rails and you will just need manifolds and possibly risers.

The 496 exhaust is perfect for stock and mildly modified engines. Merc uses it on the HP520 blue motor. It supports 525hp out of the Raylar HO525.

I replaced my iron manifolds with like new aluminum take offs and have the best of both worlds. Took 66lbs off the stern.

I have the new style aluminum on my 2000 L29 with 454 ho cam. Don't need them, was gonna run orig style, but they fell into my lap. They say the alum are all problematic and have since been using exclusively iron. OP is replacing manifolds out of paranoia, so he wants the MOST durable, problem free setup available. But then is it really paranoia? Cuz let's face it. ALL our manifolds are really trying their damndest to fail and spray water into our engines.

Anyone have any thoughts on the boat other than that stupid looking Bimini?

Chris