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exhaust and riser replacement on305 US marine-gctid364424

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    exhaust and riser replacement on305 US marine-gctid364424

    I know some of you have replaced manifolds and risers on your gas 305's. Am thinking of doing the same. I think they were actually Chris craft vintage, but would greatly appreciate info on where to get them, about how much you paid, and any additional info any of you can supply. Kind of a last minute decision, so time is short.

    Thanks in advance for your help, Jeff

    patti ann too wrote:
    I know some of you have replaced manifolds and risers on your gas 305's. Am thinking of doing the same. I think they were actually Chris craft vintage, but would greatly appreciate info on where to get them, about how much you paid, and any additional info any of you can supply. Kind of a last minute decision, so time is short.

    Thanks in advance for your help, Jeff
    I am thinking of doing the same, and have the same engines as you. But I don't think you'll get much help on this site. It is very Hino Diesel biased.

    - Glen
    Glen Sherwood
    1987 3270 twin 305’s
    Coupeville, WA


      I had a 1985 2850 Contessa with a Volvo Penta 350 (GM Block)it's a fairly easy job. Your new manifolds should come with new bolts. If they do I would suggest after you remove the risers remove two of the mounting bolts from the manifolds and cut the heads off. This will give you studs for supporting the old manifolds while you remove the rest of the bolts, they are heavy. It also helps to align the new gaskets and manifolds. Once you have the new manifolds inplace with the new bolts just swap out the studs and torque the bolts. Dont forget to use antiseze on the new bolts. Good luck.
      Burr & Francie
      1989, 3288 Motor Yacht "Kokomo"
      1961, Cal 20 (sailboat) "Deja Vu"


        I just purchased manifolds, spacer and riser/elbows for my twin 5.7 mercruisers (gas). I found that the major suppliers particularly PFP were a good source of info. I talked with Sierra, mercruiser, Barr and several others. Prices varied a lot as some offered a kit with gaskets, etc and some sold things seperately. As usual Ebay has lots for sale.

        I started out thinking Aluminum but even vendors that offered them said that if you don't need the weight advantage for performance ( I am mostly a hull speed type of cruiser) that the cast iron is the way to go. One pointed out that Aluminum when immersed in salt water most of its life also has problems that when used in an outboard motor that it spends most of its life raised up out of the salt water and that mainly being stored in air gives aluminum big advantages.

        I also decided due to access problems to have a local mechanic do the exchange and he recommended Sierra because in his experience they are large enough to have a good exchange/warranty program if you should need one. He also thinks that the castings (except for Barr) are all made in China.

        I was originally thinking of staying with Mercruiser OEM parts but the price delta was too large so I went with Sierra.

        I am also a big believer in fresh water flushing after any salt water cruises.

        I have not received or installed the gear yet so we will see.

        Good luck



          They have most engine parts and have a Chris Craft sub-category.
          Greg A.
          1994 4788
          2002 Capri 175
          "Little GFI"
          Boat on the Sac/San Joaquin Delta
          Willow Berm Marina


            Hi: I have a '89 3288 w/305 gas engs., marinized with the old ChrisCraft risers and manifolds. I've replaced the risers three times since buying the boat in 1994. Since they are fresh water cooled, the manifolds should be ok. Mine are original and have about 900 hrs. on them. Engs. are original, have good compression and burn no oil (I use Mobile-One 15W-50). Now, back to those risers. Here is the weakest link in the chain. Barr and Osco make aftermarket replacements for our Chriscraft parts. The internet is a good source to find them. Here on Long Island, I have several places to get these parts- Freeport Marine (a little high in price), South Shore Marine Supply in Massapequa, and Lighthouse Marine Supply in Riverhead. When I replaced the risers in Oct. 2010, I paid about $280 each for the resers, the deflectors were $76.50 ea. I had to re-use the exhaust elbows because they were impossible to find at that time (the "book" said I had a different size elbow-

            2 1/2" and I have 3"). Actually, several parts on my engs. are for the 454 block-The raw water pumps for instance-I have G45 Sherwood pumps-the "Book" calls for 30-2B pumps). So be sure to check the size of the exhaust elbows when you order. The risers check out ok though. The folks at Lighthouse Marine are very helpful and know what they are doing. They can be reached at 631-722-5700. I got my parts at South Shore because they were around the corner and a bit cheaper. If you need more info let me know-glad to help. It's not that hard to do the job-I take my time and can do an engine in an afternoon. Hope this helps.


              Just a comment on the idea of cutting off the heads of manifold bolts to use to help slide the manifolds into place,--this really works well but I use a piece of all-thread cut to the right length. Make sure that they are long enough that they extend past the side of the manifold so that you can unscrew it after you install a couple of the regular manifold bolts.


                I have exactly the same engines and set-up as dannyzee's boat and cannot find the elbows. They are now quite plugged (salt water use) and have found no way to grind them inside.

                I have the list of all the part # if you need them. I can post them here.

                I am also presently looking for exhaust mufflers (3" also) as mine have all the baffles broken and leak some water.

                Boat is 89, engines have 2600 hours. No oil burning but some compressions are a little low on some cylinders (piston rings I think)
                1989 3288MY 305's US Marine
                Fort Lauderdale Florida


                  Thanks for your input guys, I have the exhaust system off and new risers and manifolds with gaskets are here. I tend to agree with dannyzee on the idea that the manifolds are probably O K but didn't want to take the chance, so am putting new ones on. Problem began when I repowered last fall with new long block 350's. This spring when I turned the new motors over, the port engine was hydro locked. Pulled the plugs and sure enough, coolant in the right rear cylinder. By the way, this happened a couple of previous years with the old engine (port) but blamed it on the starter, didn't think of checking cylinders. Duhhhh! Any way, did you have the riser or manifolds preassure tested dannyzee? Just wondered how you determined the manifolds were O K? I am in fresh water, so I guess the elbows are ok, if not, are easily enough to replace later. Also made sure the supplier sent me the thicker gaskets, as I have heard some folks had trouble with them not sealing properly. Putting it all back together tues, so hope this works out. I am ready to boat, and not fix! Thanks again for your help, Jeff


                    Hi: Re: The manifolds. Several years back (in the late 90's), we were in Marthas Vineyard and heading back to LI. My temp gauge read 195-200deg. all the way home. When we got home to Massapequa (just barely), I could smell the sweetness of the exhaust as I backed into my slip and knew that there was coolant leaking into the exhaust. In the next few days, I had the risers off and sure enough there was coolant on the engine side of the risers. I had missed a blown engine by a hair. The risers were shot, and clogged with crystallized ash and the compression was down in the last cyl. next to the riser, stb. bank. This generated a lot of heat in this area. After removing the valve cover, I put a torque wrench on the head bolts and found they were all loose (about 10-20 ft.lbs). I retorqued the head to specs. and thought I may have a bad manifold too, so I got a new one. Now it got interesting. The new manifold was slightly different from the old. It didn't have a raised "boss" around the exhaust ports so there was no clearance between the top of the manifold and the valve cover. I took it back to Riverhead and they gave me a 1/4" spacer to go between the ports and manifold. That threw everything off-the alternator bracket, raw water pump bracket etc.So I was in a quandry. I went on a search to find an "old" type manifold. While talking to an old mechanic who seemed pretty knowlegeable, the question was asked as to what kind of eng. I had. When he learned that I had fresh water cooling, He said that the manifolds had antifreeze mix going through them and they hardly ever wore out. I decided to take the chance and put the old ones back. After putting on the new risers, I fired it up and it sounded good. Checked compression, that was good too. That was in the late 90's. That engine is still going strong.