Merc 260 Upgrades
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Merc 260 Upgrades
I finally found a good boat at a great price. It is a 242LS heavy monster under powered with a 5.7L 350. I am having fuel delivery issues with the carb so I figured it is time to upgrade. I ordered a Holley 600 Marine and I am looking at an Edelbrock Dual plane for some improved low end. I am also looking at some Super 23 Vortec Heads. I would like to do a cam swap while I am at it, but boat cams is not my thing. I have thru hulls on it and I know you have to be careful with cam choices and wet exhaust. I am reading about Xtreme Marine™ XM270HR; 1200 to 5200 RPM Range which seems like a decent match for my setup. Yes I will be adding roller lifters and some 1.5 rockers I had from another project.
Down the road I want to upgrade to a 454/Bravo.
Down the road I want to upgrade to a 454/Bravo.
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Fuel delivery issues. The first place you look is the pickup tube in the tank. There's a sock on the bottom of that tube that gets plugged up with stuff. And while you're at it that anti-siphon valve at the top of the pickup tube. You need to be careful going to wild with the cams with the stock Mercruiser exhaust.
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The seller said that that stuff was replaced when he did the fuel sender last season. I do have all the receipts, so I will have to look (wouldn't hurt to double check anyways). I am 90% sure that the filters on the carb is the issue. Just to be safe. I am going to replace the water separator filter and put a new in line glass fuel filter in. Is that cam that I listed considered wild? I was also under the impression that the Merc stock exhaust risers are pretty nonrestrictive for a mild 350 build from some searching (could totally be bad info though).
Either way I will throw the Holley on there and do a rebuild on the OEM to keep as a spare.
Either way I will throw the Holley on there and do a rebuild on the OEM to keep as a spare.
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Do a leakdown on it first , make sure the rings are still sealing well. If your going to pull the motor for the cam swap , some fresh rod bearings may not be a bad idea also. 310-330 horse with a single plane or performer rpm, cam heads ect is about it with cast iron exhaust manifolds for a diy quicky upgrade.
#5
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Welcome to Formula!
Do not do a thing to that 260 other than to get it running right so that you can use it for now as-is. You will not see any measurable performance improvements with trying to get power out of the 350. You'll be throwing money away.
The 242LS is too heavy of a boat for a small block. They need a lot of power to get going, and a small block isn't going to cut it. Save your money for a big block with Bravo conversion.
They're heavy and built to take a beating in comfort. Keep in mind that even with a 454 Mag they're only good for mid-50's.
Do not do a thing to that 260 other than to get it running right so that you can use it for now as-is. You will not see any measurable performance improvements with trying to get power out of the 350. You'll be throwing money away.
The 242LS is too heavy of a boat for a small block. They need a lot of power to get going, and a small block isn't going to cut it. Save your money for a big block with Bravo conversion.
They're heavy and built to take a beating in comfort. Keep in mind that even with a 454 Mag they're only good for mid-50's.
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Merc 260
I had to pull my twin 260's a few years back and went with Edelbrock Performer top end. Cylinder Heads and Performer Quadrajet intake. However, I also went to GLM aluminum exhaust with 4 inch outlets elbows etc. The heads gave a boost in compression. I noticed a difference in performance but not night and day. Additionally I lightened up the boat quite a bit in the process because the aluminum top ends on both engines pulled quite a bit of weight out of its posterior. All that said, if the boat you have is as heavy as the guys are saying. I would probably get the 350 running right and find a 383 or 377 small block to swap in later. I am happy with what I did and I gained some speed etc. but more importantly the handling of the boat is much better in my opinion. Aftermarket heads or vortec should pick up 30 to 40 hp as long as the exhaust breaths well enough. I kept the stock cams because I didn't want any issues with reversion. The old 260 is old tech, you would probably be ahead of the game to get 350 vortec based engine or 350 roller cam aftermarket head engine,, better yet a 383 roller engine with good heads. I think at that point you would have some power you could feel the difference.
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I have had a bunch of 23 to 25 boats with single small blocks. none were impressive in any way. Tom is right. go big block. don't try to make power with that 350. john, post 7, has a twin small block 26. a fast boat with stock power. and he removed 4 iron heads and 4 sets of iron intakes and exhausts. that is a lot of weight. and picking up 100 hp a side plus weight loss is night and day in a boat like that. {edit: he left the stock cams in. vey little power gain then...} to get a small block to pull like a big block is a major expense and you will be at high rpm's. start shopping for a neglected bravo boat with a bad 454 in it. I found a bayliner arriva cracked block shot interior bravo boat for 1500. every bracket, water pump with fuel pump, drive oil bottle, everything. sold trailer with hull still on it for 300. was a trailer fresh water boat so drive was beautiful. in fact there is a similar setup near me now. he is firm at 2500. but it is a cracked 454 mag efi setup. hull and interior are saleable and decent. in fact this 22 crownline would be a decent runner with your 260 merc setup in it. then you find a gen 5 or 6 block and put this setup in the formula. I almost dragged the boat home a couple of times, but I have a spousal unit who is already unhappy with my existing yard full of boats.
Last edited by dereknkathy; 07-19-2017 at 05:59 AM.
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I have always liked the looks of the Formulas. I almost grabbed a 1980 233LS before I found this one. I prefer the early 242 since it has a little more deck space and a teak swim platform. Solid advise from all of you and I will take it. I am actually going to look at a junker boat with a bravo setup for parts on Sunday. Was there a specific year that they started mainly using bravos? For this season, I am still going to convert the 260 to a Vortec since I got all the required parts for under $400. I will do the compression and leak test before anything else and also verify that I don't have any unknown fuel restrictions. I wonder where my torque wrench is? I never hope to make this a speed demon. I just want a good ride in the Erie chop and reasonable mpg on plane. It is solid, it is heavy and it is a hell of a lot of fun compared to a 20 open bow.
While asking questions. The 1986 is the 30th Anniversary edition which is pretty cool with all the badging. My gel coat seems to be coated with something. When power washing the crud off. This stuff started flaking off of the gel. It looks almost like polyurethane, but its only a few thou thick. What could this stuff be and what is the best way to remove all of it and or replace it? I will try to get some pics.
Also where can I look for a OEM replacement fresh water tank?
While asking questions. The 1986 is the 30th Anniversary edition which is pretty cool with all the badging. My gel coat seems to be coated with something. When power washing the crud off. This stuff started flaking off of the gel. It looks almost like polyurethane, but its only a few thou thick. What could this stuff be and what is the best way to remove all of it and or replace it? I will try to get some pics.
Also where can I look for a OEM replacement fresh water tank?
Last edited by ngen33r; 07-20-2017 at 12:50 PM.