Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

[chris0061]

Hello again. I just bought a pair of center riser manifolds to put on my 1984 Mercruiser 260 and they have the 4" elbow with the other elbow that ovals at the pipe end. Can I put that set up on my 3" y pipe?????? here is the elbow and my why pipe is 3 inch round.

 

[chris0061]

Re: Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

OK no responce. let me ask you this then, Can I take a pair of regular round at both end elbows, 4 inch from the riser to the y pipe and use a 4-3 bellows to hook up to the y pipe? I just want to make sure going from 4 inches out of the riser to 3 inch y pipe will not effect performance.

 

[maxxman04]

Re: Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

most "custom" work is nothing but trial and error. taking measurements, adapting things from your own creativity. i personally adapted a set of BARR center rise exhaust manifolds and risers, which were designed for omc exhaust, to my mercruiser 5.7L. i had to buy 3" bulk wet exhaust hose to go from my risers to my elbows, to get the right length, and then bought a pair of 4"x4" bellows between the elbows and Y pipe. it took a bit of research, and using non typical parts, but is not impossible. i do caution tho, if you ever decide to sell the boat, keep track of what parts you used, even part numbers are best, so that the new owner won't have a headache trying to figure out what you did. good luck

 

[Bondo]

Re: Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

Ayuh,... The Key to making it work will be Finding 3" to 4" rubber connectors....

Merc has used both the 3",+ the 4" y-pipes for Years...

 

[chris0061]

Re: Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

OK I posted again but should have just came back to this post. I found a pair of elbows that go from 4 inch to 3 but when I installed them they landed on top of the y pipe tube. So I need to get something longer for a tube to reach the elbows. They do line up off the riser to the y pipe the tube that connects them is just to short so I'm thinking of going to Lowe's and getting some heavy duty tube and cut it to size and connect the elbows to the y pipe that way.

 

[rusobr2]

Re: Putting on 4" center riser man. to 3" y pipe. Mercruiser 260

i'm kinda going through the same thing right now --as we speek--the 3 to 4 rubber boots ,you can buy at irrigation suppliers --for about 6.00 bucks each--then i went to exhaust shop,and had 3" pipe bent to 90%,or there abouts--with a ft. extra at each end of bend--then cut to fit--you can also get the 3" rubber boots at same supplier-just my exp.
steven