Mercruiser 228 to 260 Engine Swap

"I have a '82 Webbcraft th

"I have a '82 Webbcraft that has a Merc 228 Type 1 drive. Due to a missed drain plug when it was winterized, I had a busted block. I bought a long block 350 and have it ready to put in. Does anyone know if the 228 outdrive will handle the increased redline RPMs of the 350? The outdrive has been totally rebuilt in the last 4 years. The upper and lower were done at different times. From everything that I have read, the HP difference from 228 to 260 won't be an issue, but not sure on the RPMs. According to the sterndrive book I have, the redline on a 228 is 4200-4600. The 350 will redline at @ 5200 I think. I don't want to blow the outdrive apart and wanted to know if anyone has any experience with this.

Thanks,
Chris"

"Nope, Merc manual states 4800

"Nope, Merc manual states 4800 top wot rpm. for 5.7l 350 cid 260 hp. They even have this info on my engine cover as 4400-4800 wot.
Though I take mine to 5000 regularly for short stents. (been modded)
Be sure to re prop for increase in power to accomodate this rpm level at wot, and also you should have a 1.50 or 1.47 ratio with this combo.

Kurt"

"Thanks for the info. I gues

"Thanks for the info. I guess I didn't see that in the book for the 260. Any suggestions on prop? I run a 3 blade 14.5" x 19 pitch aluminum Michigan Wheel now and with the 305 that I busted, ran right at 4350 RPM. Would a 21 pitch 3 blade be enough to keep the WOT RPMs to 4800 or less with the increased HP? My boat is about 3200 pounds when I take it out.

Chris

BTW, I left the 228 valve covers on the new 260. My little secret under the hatch."

"Chris;
I would try the same

"Chris;
I would try the same 19" prop at first, then see what WOT RPM you get after break in. You may be able to swing a 21", but my guess is at 3200 lbs you will be better off with a 19", maybe cupped.
Rod"

"Like Rod said, your probably

"Like Rod said, your probably good with the 19. I went from 200hp to 350hp and figured I would need a huge pitch, but I only went from a 19 to a 21. It's all trial and error."

"I am fairly sure youd be at 4

"I am fairly sure youd be at 4600-4800 with 260hp
considering previus performance and agree the 19" cupped sounds like a good start or maybe
a vented 21" if you over rev with 19". Also must consider what you mainly do with boat IE wake boarding, skiing, and weight carried. When I have 5 or six people and wakin I use a 17" cupped
to rip the boarders out of water. Everyone Likes the deep water starts with 17", but must be carefull as I easily over rev with that prop.
The 17" also kills my economy.

Kurt"

"I tried to use a 4 blade 20 b

"I tried to use a 4 blade 20 before and got a good hole shot, but horrid top end. The 3 blade 19 worked good for kneeboarding, tubing, and some skiing. Most of my issue has been that everyone loves being on my boat and I constant run up to the weight limit with people and coolers. I will definitely give the 19 a shot to start and go up if I find that I have a RPM situation. Thanks for the advice all. BTW, I am finishing up an engine swap and a wiring, gimbal bearing, and bellows swap on my boat. If I can return the advice I sure will.

Chris"

"Follow up problem. I have a

"Follow up problem. I have a serious bogging down problem. First let me say what I have replaced with the new engine. Plugs, plug wires, coil, cap, rotor, condensor, points, fuel pump, fuel filter (twice just in case) and carb which is a freshly rebuilt Quadrajet. The only carryover from the old engine is the distributor itself, the intake manifold, and the exhaust manifolds.

Out of the water, on muffs, the new engine PURRS and revs freely. I have double and triple checked the timing and it is right on spec with the book. The dwell on the points sits at 30. At idle from the dock, it is perfect. As soon as I put throttle to it, it seems like it is struggling to go. To me, it feels like it isn't burning the fuel and running extremely rich. I can get it to turn close to 2000 RPMs, but it is struggling all the way. If I try to push over that, once in a while I get a backfire.

I am leaning towards something in the mechanical advance of the distributor being jacked, but I really don't know for sure. I have replaced everything in the fuel and ignition system except for the distributor and the wiring. I traced all of the wiring and it seems solid with no corrosion.

Any ideas? I am at a loss and don't want to have to buy a new distributor as a diagnosis step.

Thanks,
Chris"

Sounds like the carb is wrong

Sounds like the carb is wrong for that engine.
I would run a compression check first just to make sure the engine is mechanically healthy.

Are you getting black smoke or the smell of unburned fuel? What do the plugs look like?

Rod

""As soon as I put throttl

""As soon as I put throttle to it, it seems like it is struggling to go."

If it has an extra hole or two in the accellerator pump lever, set the pump rod in the hole closest to the pump rod on the lever for more fuel at throttle."

"The carb came off an OMC Cobr

"The carb came off an OMC Cobra Chevy 350. Compression check is good. I just bought a new long block. No black smoke, a little unburned fuel. I'll check the plugs in a little bit and post again. I tried the Mercarb Rochester Quadrajet 500cfm that was on the 228. It must have some issue as the fuel was coming out the side of the bowl at the seal. I had the 650 sitting there as my father in law upgraded to Edelbrock's on his boat.

As to the accelerator pump, the pump rod doesn't have any adjustment holes. I don't get a choked out from not enough fuel feel. I get a choked out from too much fuel feel from it.

What are the chances that my replacement fuel pump is putting out too much pressure and sticking the floats open on the carb?"

"Well, I got it fixed. 3-fol

"Well, I got it fixed. 3-fold problem.

1) I got some bad gas when I topped off the tank after the new engine was installed and I was going to the lake for the first time. There was no water in the separator the first time I swapped but this time it was full. I pumped the tank out and put it back in through a filter and a water separator.

2) The in-line filter must have absorbed some water and was partially blocking. New one in now.

3) This is the big one. I really can't find an explanation for it besides something in the distributor possibly shifting. I pulled the distributor again and made sure it was set in right, timed it again and went to the lake. I had the same "dogging it" issue, but without the backfiring. So, while on the water, I moved the timing counterclockwise about 10 degrees. This improved it DRAMATICALLY. I would then go again and keep moving it until it was perfect. The boat runs like a champ now. I moved the timing almost enough to account for me having the distributor off a tooth, but not quite. I really am not sure what the explanation is for this but everything works fine.

I definitely need a new prop though. The 3 blade 19 give me an incredible hole shot. From dead idle to fully on plane in 6 seconds. For a 3200 pound boat without me and the family and coolers, it rocks. The issue is when I am running about 2000 RPMs and hammer it, it feels like the prop is slipping and not biting like it should. In my mind it feels like the new engine has more torque than the prop can bite in the water when we are moving. I am going to look at a 3 blade 21 or a 4 blade 22. I'll try them both to see what works best with pulling a tube, kneeboard, and skiers.

Thanks for all of the help.

Chris"

"Chris:

I have a 3200 lb. B

"Chris:

I have a 3200 lb. Baretta w/a 4.3L 175 HP 2 BBL carb. I use a 21P X 15.25" SS prop. Engine puts out 4,500 RPMs on the top end trimmed out @ 44 MPH by speedo w/ust me and 30 gal. of fuel.

Stick w/a SS 18P or 19P cupped 3 blade prop for all around use. A 4 blade 17P will pop skiers up like bottle rockets but you'll swear you are towing another boat at WOT. Aluminum just has too much flex w/a big load. Attached is the prop finder for your boat. I used 4200 lb. as your loaded wt.

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