Will a Merc 3.0 Manifold work on an OMC setup?

TwoBallScrewBall

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Simple question. Will a Merc 3.0 Manifold work on an OMC setup? I know the manifold to head mounting is the same, I need to know if the elbow will bolt up. It sure looks like it, and I found an awesome deal on a brand new Barrs manifold for less than $100, but it says for Merc. Need to know if it will fit. <br /><br />Thanks!<br /><br />Steve
 

Bondo

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

I'm Sure it'll take a little "Creative Engineering"........<br />And,<br />You Might find some of the Bolt Holes, Missing............ ;)
 

TwoBallScrewBall

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

Yeah but that's something I'm good at if ya haven't figured that out already! <br /><br />Actually, when I put my OMC gasket up to the head of my new engine, which was a 'merc' block, a couple ports did not *exactly* line up, there was a small amount of gasket overhang. It lined up perfectly on the manifold though. I think I might actually be better off with the merc manifold (and gasket) the more I think about it. <br /><br />The major concern I have is the elbow bolting up, because I think that the OMC uses a 4" tube out of the elbow and merc uses a 3". I want to use the OMC elbow. From the photos I have it looks the same but I want to make sure. <br /><br />The only thing that bolts to my manifold is the carb and the throttle cable bracket. As long as the carb and elbow goes on I can make everything else work.<br /><br />Thanks!
 

Bondo

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

Yeah but that's something I'm good at if ya haven't figured that out already!
I Have, We are a Breed of Our Own....... ;) <br /><br />I can't help you with the OMC stuff....<br />I know Merc has used 2 different Risers on the I-4s.... <br />The early Mod.1s,+ the Alpha1s......<br />The Mod.1s are a Blocky looking, square edged riser that has a Water drain in it........<br />The Alpha1s are a Smooth rounded riser that drains itself..... No Petcock.......<br />And, If I'm not mistaken, the position of the down-pipe is moved slightly to the port-side of center......<br /><br />I Know, More is Better.....<br />But, 454s are run thru a 3" exhaust.......<br />I really Doubt your 181cid is going to be Choked by a 3"riser........<br />You'd Gain More by port-matching the new head,+ manifold, <br />Than you'd Lose on the 1" difference.....
 

TwoBallScrewBall

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

I'm not worried about the restriction of the 3" riser, I'm worried about the 3" merc riser mating with my 4" omc exhaust going to the transom/outdrive. I need to look into this more, if I can get the merc manifold and riser to mate up with the OMC J-pipe I'm probably going to go that route since the head ports will match up. <br /><br />Just had an idea.... uh oh.... how about removing the j-pipe, blocking off the outdrive exhaust, and running a thru-hull? That would solve my problems I think! I am in NJ and the guy with the manifold is in CT, about a 3 hour drive, I think I'll be making a trip this weekend to eyeball things over and get a feel for whether or not it's going to work. I can get the merc manifold for about $100 it looks like, or the OMC for $300. OMC riser is $104, Merc riser is about $80. From there, I would need another $100 (estimate) into the merc manifold setup for a stainless pipe and flapper out the transom. I have the holesaw...haha. <br /><br />I obviously have to think this over here......
 

Bondo

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

That's what I did when I pulled the 3.0l out,+ Dropped in the 4.3LX..........<br />Twins.....<br />I Made them Myself.............. :D
 

Bondo

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

Steve,<br />When I was out in the shop,<br />I looked at the differences between the Mod.1s,+ the Alpha1s.......<br />The Mod.1s dump out of the riser Straight behind the manifold..........<br />The Alpha1s dump out 5"s to the port-side behind the manifold.........<br />That gives you 2 different Targets to get your down-pipe to line up with.........<br /><br />Hope this Helps...............
 

TwoBallScrewBall

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Re: Will a Merc 3.0 Manifold work on an OMC setup?

Thanks Bondo. I appreciate the help there!<br /><br />I've been talking with my dad a bit about what I was thinking of doing with the Merc setup. He said it wouldn't be a bad idea, execpt that he was a little leery about cutting through a 16-year old transom. Understandable (let sleeping dogs lie kinda thing, it is a bayliner!). Anyway, I was telling him that it would be about a $200 price difference between going merc thru-hull and OMC thru drive. Today he was over babysitting my 10 mionth old daughter, and when I got home from work he said that he'd throw me the extra $200 for my birthday (this month, the 16th) to get the OMC parts. So that's settled! :) Now just have to find the best price on some barr's. <br /><br />Does Iboats sell mainfolds? I've been looking but haven't seen them here yet. If not, anyone have any tips on where to get a good price on them? I'd need the whole 9 yards, manifold, riser, and front plate.
 
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