HELP mercury bridgeport problem

[CharlieB]

Re: HELP mercury bridgeport problem

Where are you?
What floats are in the carbs, original, or have you changed them?
How high are the floats set?
What jets?

 

[j_martin]

Re: HELP mercury bridgeport problem

Where are you?
What floats are in the carbs, original, or have you changed them?
How high are the floats set?
What jets?

Charlie's going for original setup screwups and common problems. Carb part number is part of the analysis.

jm

 

[j_martin]

Re: HELP mercury bridgeport problem

Now I'm beginning to wonder about excess compression and much higher fuel octane requirement. Maybe for grins and giggles try a pony can with a couple of gallons of 100LL avgas in it.

 

[Faztbullet]

Re: HELP mercury bridgeport problem

Is the intake cross drilled? What type/pitch prop? What is motor height? These engines like a little timing before fuel so open the throttle arm to carb roller gap to about 3/16". Also make sure jets are in correct carbs as looking at the carbs the left side feeds cylinders 1/3/5 and right side feeds 2/4/6..

 

[pugo]

Re: HELP mercury bridgeport problem

What boat is this on, and what prop are you using? Is it ventilated?

What carbs are on it. Numbers off a carb will help. Should be a xx-xxxxx number on the idle port cover plate that is the best clue.

Obviously you inheritted the problem. Do you know any (truthful) history about it?

its on an 18ft ring, i had(came with) a 28pitch stainless cleaver, but i currently have a 22pitch stainless prop off my old boat on it to try, when u say ventilated, i am assuming the fuel tank and yes i checked all that i have even run it with the fuel tank open to try it
they are wh 46 carbs, i think 76 mains, however i noticed that before i had it 2 of vent jets were missing, however they were not in on cyl 2+5 so have swapped these last night as somebody else commented that they were in the wrong place,
Yes inherited the problem, bought the outfit cheap, and i am starting to realise why lol, The history from what i been told was that it was once a race outfit for a certain class in the uk..! as for carb numbers exactly i shall get them tonight when i get to the boat again, compression is about 135 to 138 across all 6,

'CHARLIEB' , i am in the uk, the floats are original and i have checked that they were not leaking, set the float heights as per mercury told me and presume they are fine as its fueling is fine once up on its main jets, mains are 76 or 79 cant remember off top of my head now

FATZBULLET, hmm , i think you could be on to some thing, my carbs start opening exactly as the arm starts advancing the ignition, is this not right ?, the prop originally was a 28p cleaver but now down to 22 pitch as thought it might be the wrong prop on the boat hence bogging it down......plus with the 28 pitch prop on when it did clear and go.....my better half nearly **** herself lol, plus the vent jets weren't in the right holes so have now changed that last night, might test run her on saturday just to see if anything has improved


ALL
you guys are great, i really do appreciate all the comments, as its all stuff i can try before driving myself mad

really do appreciate all this

Pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

Hello,
The plot thickens.........

By ventilated, I meant the prop. It is exhaust relief holes in the barrel to allow it to spin up or slip when the forward speed through the water is low.

WH46 carbs, stock jetting is:
Main .080 .082
Idle .056
Vent .096 (none)

Mains and vents on cylinders 2 and 5 are richer.
Note that the carb barrel in question feeds the cylinder on the other bank, thus #2 barrel is starboard top.

It's leaned out quite a bit. Fatter jetting would be much safer to run of course, and probably much more friendly to pleasure boating. Note that on idle jets smaller is richer.

Timing and linkage progression might have been messed with to the nth degree, also. A formal Link-n-sync might be in order.

Tag team to Fatz

 

[pugo]

Re: HELP mercury bridgeport problem

Hello,
The plot thickens.........

By ventilated, I meant the prop. It is exhaust relief holes in the barrel to allow it to spin up or slip when the forward speed through the water is low.

WH46 carbs, stock jetting is:
Main .080 .082
Idle .056
Vent .096 (none)

Mains and vents on cylinders 2 and 5 are richer.
Note that the carb barrel in question feeds the cylinder on the other bank, thus #2 barrel is starboard top.

It's leaned out quite a bit. Fatter jetting would be much safer to run of course, and probably much more friendly to pleasure boating. Note that on idle jets smaller is richer.

Timing and linkage progression might have been messed with to the nth degree, also. A formal Link-n-sync might be in order.

Tag team to Fatz

right, next instalment

prop has holes through the barrel for exhaust and small rectangle cut outs on end of barrel...so yes possible vented

the mains are 79's on all 6

and thank god you told me that the carb chokes feed the other side as i probably still have vents in wrong place..!

going to try to link and sync this afternoon when i get home

please keep offering advice as i honestly think you lot are going to cure this...!

Pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

right, next instalment

prop has holes through the barrel for exhaust and small rectangle cut outs on end of barrel...so yes possible vented

the mains are 79's on all 6

and thank god you told me that the carb chokes feed the other side as i probably still have vents in wrong place..!

going to try to link and sync this afternoon when i get home

please keep offering advice as i honestly think you lot are going to cure this...!

Pugo

Yep, that's what's called "vented"

Question comes to mind. Is the bleed line routing correct?

Also comes to mind is the question, has some creative drilling been done on these carbs?

Bleed lines are pictured in the manual.

If, when you do the link-n-sync, idle then has to be radically adjusted for speed, you can look at yer carbs with a jaundiced eye.

 

[pugo]

Re: HELP mercury bridgeport problem

UPDATE...!

ok i finally did the link n sync, all bleed lines are as per manual, hoping no creative drilling has took place, adjusted throttle arm correctly, put boat on the water on saturday, now she idles beautifully, you put her into gear and she purrs , accelerate and the bow lifts as if she is going to go , then she starts to peter out, but now you just press the choke for 2 seconds and she is on the plane and away, you do not have to pump the throttle any more, and when you throttle off now some of the time she just accelerates through the problem without choking....!

We are getting there...!

Pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

Try these items in this order.

1. Check the carb linkage. They all must open at exactly the same time.

2. Resync the carb linkage, with a small gap between the throttle roller and the throttle cam. Sometimes they like a bit of advance before the throttles open.

2. That failing, (bout 1 in 4 it'll help) put it back to stock, and increase your main jet size to stock.

Thought---> If it was used for drag racing, it used an over the hub prop which has a lot of torque relief at low speeds, plus it was probably a low pitch for max acceration for 1000 feet. Mains leaned as much as possible without destruction for a bit more acceleration. Went through the ramp to rpms so fast that lean mix in the mid range didn't make any difference.

Double check your throttle cam setup. I think there are 2 different cams possible on that engine.

hope it helps.
John

 

[pugo]

Re: HELP mercury bridgeport problem

Try these items in this order.

1. Check the carb linkage. They all must open at exactly the same time.

2. Resync the carb linkage, with a small gap between the throttle roller and the throttle cam. Sometimes they like a bit of advance before the throttles open.

2. That failing, (bout 1 in 4 it'll help) put it back to stock, and increase your main jet size to stock.

Thought---> If it was used for drag racing, it used an over the hub prop which has a lot of torque relief at low speeds, plus it was probably a low pitch for max acceration for 1000 feet. Mains leaned as much as possible without destruction for a bit more acceleration. Went through the ramp to rpms so fast that lean mix in the mid range didn't make any difference.

Double check your throttle cam setup. I think there are 2 different cams possible on that engine.

hope it helps.
John

Jon,

Yes they all open at the same time, last time i took her out i had the throttle link about 3/16 off of the cam, am now wondering if that was a bit to much advance before the throttle opened, i have now set it to about 1/16 off, As for drag racing, they dont do much of that here in the uk so think it would be more for round the bouy racing, as it came with a 28p cleaver which looked like it had not been off in years and the boat felt like it was doing 100mph with it on, now dropped to a 19p , however she had the same problem with the 28p on....!
I have actually got a mercury trained outboard mechanic coming out on the boat today at 5pm so am preying he (with his experianced eyes) can cure this once and for all, if not look out on youtube for 'CRAZY UK BOATER PERFORMS VIKING BURIAL ON HIS BOAT' lol

Pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

Bet he comes to the same conclusion. It just needs to be jetted a bit fatter all around. A 28 cleaver on it had to be pushing a pretty light boat.

On the burial. There's a coupla dozen Yankee boaters that would pay to ship the corpse across the pond.

good luck.
John

 

[j_martin]

Re: HELP mercury bridgeport problem

What'd he say! What'd he say!

 

[pugo]

Re: HELP mercury bridgeport problem

He has informed me that he thinks i have a blocked idle cicuit on 1 carb, my ignition is slightly off as i have set it for untuned and this thing is apparently tuned to the max (not quite sure what he meant)??, he is coming round next tuesday to strip and repair as required , he also said (although i thought it was running lovely on idle) it is running as rough as old boots
i bow to all you guys for the assistance and patience you have shown me, and i now defer to the expert i have to hand, however if he finds anything i shall update this thread with the info

Regards

Pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

I'll translate for you. The stock carburetion is quite fat. It is reliable and cylinder temps are kept down during overloads (wrong prop), overheats (wrong trim) etc. It's what I call a safety tune, ie protect the warranter. Your mains are .003 or more leaner than stock, which would put it much closer to dangerous, but perform better. I suspect max timing might need to be slightly less for that setup.

We've had to trust your ear, so we missed the rough idle. That would be a big clue on your problem. It has to be hitting pretty well on idle before it'll respond smartly to throttle.

Keep us posted. We're curious as racoons.

 

[pugo]

Re: HELP mercury bridgeport problem

update...!

ok the guy set all the engine up and it does tickover lovely now, however, i think i may have a clue to my problem!!
I took her out the other day and noticed that when she starts to bog heavily and I need to choke her to get her to plane it is usually if I have been cruising at low speeds and if I give her the preverbial beans for considerable time all seems to be well and she planes happily from rest.
I took off the engine cover and cruised around off plane for about ten minutes and then checked the block temp with my hand and she is stone cold, get her on the plane and take her up to 6krpm and hold her there for a little while and she comes up to temp and works fine.
Got her home whipped off the stat housings and found a washer in each housing and no stat, now I am wondering that this is probably ok for flat out racing but probably not suitable for pottering around and ski-ing on as she seems to be too cold, also I have no poppet valve I have a modded housing where the poppet valve looks like it used to go..!
So the question is ?..do I need stats in the engine or are the washers causing my problem????? My brain is telling me stats are the way forward , but can I run them with no poppet valve ????


Pugo

 

[Faztbullet]

Re: HELP mercury bridgeport problem

If it a one piece adapter you cant run t-stats or poppet...

 

[pugo]

Re: HELP mercury bridgeport problem

it has a small plate with a brass outlet as a poppet valve cover, however i cannot see why the stats cant be fitted in the heads as surely they will replace the washers and control the flow/cold running better ????

pugo

 

[j_martin]

Re: HELP mercury bridgeport problem

Let me give you a hint. Fazt is into the possibility that you have racing gear, and some parts do not work well enough together to keep your engine in one piece. Racing, of course always compromises some aspect of performance (idle, for instance) for another (ie fast).

Pay real close attention to what Fazt says, and ask questions if you don't know what he's talking about. He'll get you there, or tell you exactly why he can't.

 

[angushuck]

Re: HELP mercury bridgeport problem

Thanks for this guys, this is really a big help for me too