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Wonbt come up to speed

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aq260a_in_astor

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"OK, I've been working on

"OK, I've been working on these engines and related systems for a while now (replaced a bunch of auto parts) and they are now running pretty good. Except I still can't get up on plane. The dual AQ260As are topping out at just over 3K RPM. I think they should be hitting around 4200. The legs are 280s and the props are 15x19 3 blade. It's a 79 Bayliner, 32ft which the docs says should come on plane and hit 30mph. I'm topping out at 11mph."
 
"First, how are your trim tabs

"First, how are your trim tabs working? I assume that a 32' boat must have trim tabs. If you have them, lower them completely until the boat is on the plane, then correct the angle until the boat has a reasonable trim angle.

Second, consider testing 15 x 17 or 15 x 15 props and see how it goes. Your boat could be overpropped. I have a 22' with a 350 Chev (ex-AQ311) and a 280 sterndrive and I am using a 15 x 17 propl; the boat does easily over 30 knots with this arrangement.

Third, how heavy is your boat? If the boat stringers, transom etc are waterlogged, the extra weight will make it very difficult for the boat to plane. Consider putting the boat on a trailer and weighing it on a road scale."
 
"Unless you've got two ton

"Unless you've got two tons of water in the bilge, 500+ horsepower of engines should get a 32 foot Bay Liner up on the plan, water logged stringers or not. I've got a single 5.0litre on my 30 footer and trim tabs up or trim tabs down it will still plane.

Suggest you have an issue with you engine controls if both engines are punching out the same amount (limited) power. If one engine was revving out correctly and the other was lagging I'd say it was an engine issue, but symetrical underperformance by both engines sounds like controls."
 
"Ayuh,..... I just borrowed th

"Ayuh,..... I just borrowed this from a Bud at another site,.....

Engine Won't Reach Operating RPM. Check

Fuel condition. Type and Octane possibly old fuel
Propeller pitch or diameter, damaged blades
Restricted fuel pickup tube or anti siphon valve Fuel System Test
Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
Marine growth on hull and outdrive
Wrong gear ratio in outdrive
Restricted carburetor air intake (clogged flame arrestor)
Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
Poor cylinder compression Compression Test
Carburetor defective, or wrong type.
Fuel pump pressure and vacuum
Boat overloaded, improperly loaded, or improperly trimmed.
Engine Overheating
Engine timing and ignition system operation
Remote control cables and linkage for proper travel to open throttle plates fully."
 
"Hi, I have a 29ft Fairline Mi

"Hi, I have a 29ft Fairline Mirage family cruiser with 2 x aq145a’s and 280 outdrives. I use 15x17 counter rotating props and the boat achieves 28 Knots with a clean bottom easily, revving at about 4800. Hope this helps."
 
"OK that gives me some things

"OK that gives me some things to look at this weekend. Here is some more info:
port - new carb, distributor, fuel pump, plugs/wires
stb - new carb, distributor, starter, alternator, head job, prop, plugs/wires
I had a complete bottom job done a couple months ago - including full service on the outdrives (rubber, zincs, oil, etc)"
 
"Another thing you should look

"Another thing you should look at is at the trim pin in the transom shield. There are three possible positions, and it is normally placed in the middle or sometimes in forward position, but seldom in the aft position. If placed in the aft postion, the boat may have a hard time going on the plane because the bow will be lifted and the propeller trust will be far from parallel to the water surface. This is why I suggested that you adjust the trim tabs all the way down before attempting to go on the plane, so that the bow is being forced to go down.

You said you replaced a bunch of auto parts. I hope that the cams in your engines are the correct ones for marine application, as a cam designed to run on a car will not give the engines the torque they need to put the boat on the plane.

Also, have you retrieved the anchor before attempting to go on the plane? (just kidding
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"I don't know if the previ

"I don't know if the previous owner(s) replaced anything internal with auto parts or not. The carbs, distributors, and alternator were all auto. I'll go swimming when I'm out this weekend and check the trim pins and the trim tabs. I know the trim tabs were working before, but I'll double check and give this a try."
 
You should never put an automo

You should never put an automotive alternator or starter in a boat. They are not built to prevent spark and could cause an explosion. This is very dangerous and should be removed at once. Also if something happens and your insurance company finds out they will not cover it.
 
"Hey , anyone of you guys have

"Hey , anyone of you guys have a used Solex 44PHN carburetor laying around or even just the float ? I have been on the computer 4 days searching for a new float and no luck ."
 
"Yes the previous owner didn&#

"Yes the previous owner didn't want to spend the money for quality marine parts. I think I've replaced all the auto parts -
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Got out there this weekend and found the following:
trim tabs are not working - stuck all the way up, so I need to fix that (power to the switches, but that's as far as I could get so far)
both engines will run at 4500 RPM without any problems - when they are not in gear, so they are getting gas and air. I think it might still be useful to clean the spark arrestors, but I don't know how to do that (yet)."
 
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