Pacific 22 / Mermaid

[Andy Cox]

Hi All,

Just thought I'd update you on my quest to find out a bit more about my Mermaid Turbo 4. The chaps at Mermaid are excellent and Chris in particular is very helpfull indeed. He looked up the original build card when the engine was signed over to the MOD and told me that it was set up at 140hp @ 2600rpm with a no load WOT of 2870rpm. I explained that I would like to set the pump up to give about 160/165hp and he suggested that I take the fuel pump off and have it set up properly, and as I have an account with Lucas, I decided to do just that. He also said that a fuel setting of 19.6cc over 200 shots at a calibration speed of 600 rpm using ISO4010 nozzles would acheive 165 hp assumig that everything else on the engine is OK. Boost pressure at 140 hp should be just under 1 bar and at 165 hp should be just over 1 bar.
So off came the pump, bit of a fiddle, and Lucas came to collect it on Tuesday. Yesterday I get an interesting call from their diesel guy who explained that the pump was delivering 26cc!! I got him to calibrate it at 19.6cc as suggested and I can now adjust it between 19.6 and 26cc. The screw needs to be turned out by 1.5 turns to adjust this. 1/2 turn =21.8, 1 turn=24 and 1.5 turns =26cc. I spoke to Chris at Mermaid about this who said 26cc equates to 200hp. I now need to get the number off the turbo to see if it is the 200 turbo or the original. Sorry this is all very boring but I now intend to carry out some tests with my workshop tacho and boost guage and a GPS to see exactly what it's doing. If it's the original turbo, I think I will keep the setting down to limit it to about 170ish hp as Chris explained that running these engines at too high a power setting for too long is going to make something go bang eventually.

Cheer for now

Andy

[Neville]

Andy,

Why not check your Wot under load. It will then probably do 2800 rpm under load if it does that in neutral, with 26 ccs going in to the engine. The next thing if it isnt going fast enough would be a simple prop upgrade.

It is important to up the prop rather than flying around at a higher rpm and a small prop, as im sure you will know. The throttle stop on the pump will hopefully be set up properly, but worth a check.

Neville

[Scary Des]

Originally Posted by Andy Cox

Hi All,

................ Mermaid The screw needs to be turned out by 1.5 turns to adjust this. 1/2 turn =21.8, 1 turn=24 and 1.5 turns =26cc. I spoke to Chris at Mermaid about this who said 26cc equates to 200hp.....

Andy do you turn the screw stop to stop? or have you marked it in some way.

Originally Posted by Andy Cox

..............carry out some tests with my workshop tacho and boost guage...............

Andy

Where do you take the tacho from? I think my guage over reads and I want to check it, the only way I can think of doing it is with an optical tacho is there another way?
Des

[Andy Cox]

Neville,

The govenor control screw still has the lead seal on it, so the RPM is still going to be 2600 but as I say I want to check it anyway with my tacho and under load.

Scary Des,

My workshop tacho is an optical one with a laser sight and I have found it to be very reliable. It's the same one that Joe Poulter uses for testing.
As far as the pump is concerned, my man at Lucas has put a series of punch marks on the top plate, 2 either side of the screw, in effect creating a straight line accross the screw with the slot in the screw aligned with the punch marks. At this position it is set at 19.6cc and so I can accuratly wind it out by 1/2 a turn at a time. The really important thing is not to forget how many 1/2 turns have been made or else its back to square one

I need to establish which turbo is on there, which I will do later today and then carry out some runs under load at different fuel settings to establish an optimum for my application. I'm hoping to do this at the W/E.

Andy

[Pete7]

Des, the tacho drive on mine is taken from a widget hidden under the fuel filters. I think it works the same way as a dizzy does on a petrol engine. Its loose at the moment so under reads at speed. It means stripping the intercooler and fuel filters out to get at it so I am leaving it until the winter.

Mermaid have a box of second hand ones which they showed me when I asked how it worked last week.

Pete

[Scary Des]

Pete

Just had a look and can’t see it, maybe that’s why it is under reading , having said that what am I looking for? (JK Why isn’t there a smiley with an exclamation or question mark? I need then all the time)

Des

[Pete7]

Des

Mine has two wires that connect to the widget, deep under the fuel filters starboard side. The widget is about six inches long but three inches locate inside the engine. The bit you can see is about the size of a small yogurt pot.

Have you got an alternator sensed one then ?

Pete

[Pete7]

Des, I was thinking about installing one of these if I couldn't get the Tacho to read properly

http://www.tinytach.com/tinytach.html

Pete

[Bill S]

Originally Posted by Pete7

Des, I was thinking about installing one of these if I couldn't get the Tacho to read properly

http://www.tinytach.com/tinytach.html

Pete

Pete,

Have a look at this

http://www.rib.net/forum/showthread....light=tinytach

it gives a uk contact for them....

Bill

[Scary Des]

Originally Posted by Pete7

......Have you got an alternator sensed one then ?....

Pete

Pete
Could be, because I can not see any wires on that side of the engine. I’m told it’s adjustable but what I don’t know is does this adjustment happen at the gauge or the sensor?

On another matter, I keep forgetting to centre the outdrive before lifting the leg and am in the process of destroying the plastic cover(we’ve all done it ), I have a spare and I’m thinking about making a fibreglass plug so I can have more spares in the future. What I can’t decide is whether this cover does much. I think that its main role is cosmetic and it does offer some protection to the bellows but other than that I can’t decide. What are your thoughts?

Des

[roohairy]

Some Dorset / Dover blocks have a mechanical drive tacho from the output below the fuel filters, some have an adaptor to send the same signal as an alternator W connection. If anyone's looking for these ASAP sell them. Also a fair amount of stuff on their website for dorset / dover blocks, more than anywhere else.

http://www.asap-supplies.com/

I think they also sell the tinytach, or something similar, but from around £150 I think. Tinytach is about $65 in the US. I was going to get one here before I sold my hull, but my buyer has had a change of heart so the project's on the go again, not enough time now unfortunately.

[Pete7]

Des, I think there are more than one type of Stern Drive cover. I had the square one but destroyed it by using full lock. I have seen others that have a curved cone shape over the bellows but dont' which is for what?

However, I have just had to replace both rams due to corrosion and the culprit was probably stainless steel bolts holding the cover on as the bolt holes and corrosion where very localised.

Pete

[Scary Des]

Pete
I think the two bits you’ve seen form the total cover, a flat topped bit that screws to the transom housing and a curved bit that is jubilee clipped to the leg, least ways that what’s on my one. I am thinking about making the bit that screws to the transom.

The rams are a pig (is that mixing my animals?)because they are virtually isolated from the rest of the drive (cos of the rubber bushes). The Engineer in the Lancing Marine workshop said I should use earthing straps to connect the rams to the transom housing, haven’t do it yet, but sounds like a good idea.
Des

[Pete7]

Des making our own sounds a good idea, have to say that mine didn't fit at all well. Suggest they screw to the transom directly rather than the leg. A bit less day light might help keep the "creatures" from growing on my bellows although I am watching the thread on skin wax stuff with interest

Pete

[Andy Cox]

Des,

When I was talking to Mike Bellamy at Lancing Marine, he suggested that an extra anode on the transom and wired internally to one of the transom shield mounting studs would be a good idea. I've fitted a 12" euro anode (MG Duff) to the transom next to the transom shield and wired it as said. Hope it helps! I like the idea of a continuity wire to the rams (same idea as Mercruiser etc).

Andy

[Neville]

The widget under the fuel filters is a signal generator for the tacho. If anybody is considering replacing their tacho, i can put them on to a VDO dealer who has some really cheap 24 volt VDO ones that run off the alternator. They are compatible with all alternators and are simple to hook up. I think he was selling them new for about £20 - £30 each which is a fraction of what they should cost.

With regards to the rams, these corrode badly, normally the aluminium base where the two hoses go in corrodes first. This is partly due to the fact that the rams are as has been pointed out 'isolated ' electricaqlly from the rest of the drive. I am sure that fitting an extra anode directly to the rams will help combat corrosion, but i am sure that i remember chemistry at school which said that anodes still work quite well at a distance (hence the fact they are used on grp boats and wooden boats sometimes never connected with a wire, just screwed on to the grp).

[Searider]

Originally Posted by Neville

but i am sure that i remember chemistry at school which said that anodes still work quite well at a distance (hence the fact they are used on grp boats and wooden boats sometimes never connected with a wire, just screwed on to the grp).

Not quite.

An anode has a radius of effect of about 12 feet but does need to be electrically connected to what it is protecting irrespective of distance.

On GRP boats the anode(s) should be electrically connected to the sterngear and this is something we check on a survey using a multimeter between the anodes and shafts / propellers / rudders / P brackets etc.

Wooden boats have a whole different load of problems and are often better off without anodes at all.


Regards



Duncan

[Neville]

Does that mean that an anode will not work at all if it is not electrically bonded to what it is protecting?

I understand about connecting sterngear etc, but i thought that they did offer some protection when not connected, ie the electrons or whatever could still travel through water for a few feet. Its been a long time since school!

[Searider]

No, needs to be bonded - hence the need for external bonding kits on Mercruiser drives and little anodes on all sorts of bits - trim rams etc.

Duncan

[Andy Cox]

Any of you guys know where I could get a copy of a wiring diagram for the Pacific 22 please.

Thanks

Andy