Engine re-build - Detroit - Desicion made - Start 03 Nov 2011

Divemaster1 said:
Well.... tomorrow should be the big day when I discover if I have a nice, smooth rumbeling in the basement again...

Liquids in the engine .... (23L oil and 31L coolant :o ), no apparent leaks ... :).

Re-comssioning of fuel system and batteries, after a tune-up check and opening of air supply in blower..., then crank the engine again for startup and idle adjustment.

Whilst being the moment of truth .... , I hope this will be eventless and that I can clean up and close down and re-assemble the furniture...

So Syd, when are you going for that re-tune ?? :D :D
Click to expand...

She will burble like a baybe ;)
 
burgundyben said:
Kinell!!
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6.9L engine, so you probably would expect somewhere areound 15 - 20L oil.... you may react to the coolant level, but remember that these are two strokes, so fire every time the piston is at the top .... that is a lot of heat to disperse of in a very short space of time .... a lot goes out the 4 exhaust valves (so even the exhaust manifold has a water jacket)....
 
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Looks like I'll be joining you in the DD rebuild club shortly. Got a DD71 series V8 coming in for recon next week, apparently its out of an aircraft tug.

Looking forward to it. Something different from run of the mill MAN Diesels,Volvo's and Cummins.

Never been inside a crank driven supercharger before. Trust it's a Rootes 3 lobe type rather than a screw?
 
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tinkicker0 said:
Looks like I'll be joining you in the DD rebuild club shortly. Got a DD71 series V8 coming in for recon next week, apparently its out of an aircraft tug.

Looking forward to it. Something different from run of the mill MAN Diesels,Volvo's and Cummins.

Never been inside a crank driven supercharger before. Trust it's a Rootes 3 lobe type rather than a screw?
Click to expand...
Welcome to the exclusive club.... As it is off a tug, I presume a "N" ... Naturally aspirated... (In DD talk, that means no turbo, as they all had roots blowers)....

V8 71's are in principle the same setups and parts as ours, but blower on top, feeding two airchambers (one for each part of the V). Tune-up is a bit more of a pain with respect to fuel rack setup, but as you are getting her in, I presume you mean a workshop setup, which makes things a lot easier. To make things cheaper, a lot of re-built parts (to factory spec) is available as exchange programme (injectors, waterpumps, alternators, blowers etc.).

V8's came with none, one or two turbo's..... pending on outtake.

Would be interesting to know configuration (Turbo or none), rating and of course how many hours run.... You putting her back to factory spec (full re-build)?
 
Divemaster1 said:
6.9L engine, so you probably would expect somewhere areound 15 - 20L oil.... you may react to the coolant level, but remember that these are two strokes, so fire every time the piston is at the top .... that is a lot of heat to disperse of in a very short space of time .... a lot goes out the 4 exhaust valves (so even the exhaust manifold has a water jacket)....
Click to expand...

Interesting, my 5.9ltr perkins push out 145hp, they have a watercooled exhaust manifold, 11 ltrs oil and about 13ltrs coolant.
 
Love the sound of those big detroit 2 stroke v8's a good friend had a pair of them in his big game fisher (pic below) however he has not long ago removed them and fitted a pair of cats....

Not sure what he has done with the stroker's but could find out if anyone needs spares (however they are in Gran Canaria I'm afraid).
 
Divemaster1 said:
Welcome to the exclusive club.... As it is off a tug, I presume a "N" ... Naturally aspirated... (In DD talk, that means no turbo, as they all had roots blowers)....

V8 71's are in principle the same setups and parts as ours, but blower on top, feeding two airchambers (one for each part of the V). Tune-up is a bit more of a pain with respect to fuel rack setup, but as you are getting her in, I presume you mean a workshop setup, which makes things a lot easier. To make things cheaper, a lot of re-built parts (to factory spec) is available as exchange programme (injectors, waterpumps, alternators, blowers etc.).

V8's came with none, one or two turbo's..... pending on outtake.

Would be interesting to know configuration (Turbo or none), rating and of course how many hours run.... You putting her back to factory spec (full re-build)?
Click to expand...

Yep, full nut and bolt recondition. We already have the gearbox from the tug in the transmission shop. Damn thing is about 4 feet in diameter. When I saw it come in I thought it was from a trawler.

Service engineers reckon the tug is built like a tank for traction.

No idea what config it is, but being a tug I reckon it will be non turbo and very low geared.

Not set up a DD injector rack since college, so I expect I will get headaches from trying to get my head round the shop manual.
 
tinkicker0 said:
Yep, full nut and bolt recondition...........
Not set up a DD injector rack since college, so I expect I will get headaches from trying to get my head round the shop manual.
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Good one !! Pictures would be great to see.... but understand if you cannot...

basically..
1) back off buffer screw
2) back off idle screw
3) Set exhaust valve clearance when injector fully depressed (circulate all 8 in firing sequence, and you can do it in one rotation)
4) Set injector timing when exhaust valves fully depressed (circulate all 8 in firing sequence, and you can do it in one rotation
5) Set governor to full fuel and disconnect row 2 ... back off all injector clevices
6) adjust cyl 1 rack untol clevis springs back when depressed .... continue down row... checking all in row.
7) disconnect row 1 and reconnect 2 & repeat steps from 6
8) connect row 1 and check all 8, with adjustments as required.
9) Fire up and set idle
10) adjust buffer screw (note do NOT let this increase idle more than 25 RPM as she'll start hunting upwards constantly rising...)
)exhaust valve
 
Well... long story, but not there just yet ....

During the fuel system connections, I slipped and knocked agains intake strainer of SB engine...., I heard a small crack which was followed by a trickle of water, which re-focussed my attention from fuel to water....
Assessing the situation, I rapidly made a "small wooden plug"...

DSC_0174.jpg


This little side issue made me occupied for a couple of hours and is the reason why I did not complete the port engine today.... but still on the boat ... afloat, and will complete the startup and idle ajustment tomorrow AM...

Anyway, next items are pretty boring and sort of for Syd who asked me to take some pictures of what to expect during tune up...

BTW Syd, the item in this pic with a wingnut is the cranckcase breather... the one in front (darker green) is the oil filter..

DSC_0173.jpg


Anyway, If you look at the sequence I have posted in my response to Tinkicker, they pretty much apply...

The idle screw, is part of the governor control unit and lies underneath a cover like this ...
DSC_0172.jpg


When cover is removed (1/2" or 13 mm) you'll see it here.... basically hex screw with 11 mm lock nut... (SS item with idle hex key and lock nut)

DSC_0170.jpg


I'll take pictures tomorrow of where to take the valve clearances, but on a 4 valve head, this is usually a 0.016" gap when injector is fully depressed... rotate engine in clockwise direction witha power bar and a 34mm socket...

The fuel injector timing tool is a pretty cheap item and looks like this ...

DSC_0179.jpg


... and in this picture you can also see from the manual on how the fuel injector clevises should act when you are setting it up with governor at WOT.

The injector timing tool goes in to a control hole on the right side of the injector and wehn exhaust valves are fully depressed, the potruding part should just clear the injector top... I'll take some more picture tomorrow.

DSC_0177.jpg


Both the exhaust valve and injector clearances are adjusted with two spanners (you should get away with a 13 mm and a 7mm)... at the back of the lifting mechanism... the 7 mm goes to the square of the lifting arm and the 13 mm (1/2") is the lock nut... note that when you finally tighten the lock nut, you will tighten the valve clearance and increase the injector clearance slightly.

DSC_0178.jpg


The last part is the fuel rack setup and in the picture below you see the fuel rack tube which holds the pushrods that goes into the injector clevises. The rack is adjusted at governor WOT with idle and buffer screw backed out. tighten the clevises (starting with 1 at front of engine) ... this is a bit of a faff, as you have done 2, this may affect 1, so you need to check 1, after 2 is done and re-adust 2 again if impacting 1 ... then on to 3, checking 2 & 1 etc... don't worry ... after a while you get used to the impact of setting, tightening and effect of locking screw (opposing) etc. Took me about 2 hrs the first time, but now down to 20 - 30 minutes for all six...

DSC_0175.jpg


Sorry for boring you all with these details..., but would rather share with all than keeping it on a 1 to 1....
 
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burgundyben said:
Interesting, my 5.9ltr perkins push out 145hp, they have a watercooled exhaust manifold, 11 ltrs oil and about 13ltrs coolant.
Click to expand...

At 6.9L, we could push out 485 Hp .... but current configuration is somewhere between 385 and 410 ... at a sedate WOT 2300 RPM

Your perkins are these the ones they later added an intercooler to and pushed up to 175 Hp?? ... used in the JCL Moonrakers etc.
 
Divemaster1 said:
At 6.9L, we could push out 485 Hp .... but current configuration is somewhere between 385 and 410 ... at a sedate WOT 2300 RPM

Your perkins are these the ones they later added an intercooler to and pushed up to 175 Hp?? ... used in the JCL Moonrakers etc.
Click to expand...

Similar, mine have charge coolers, the 175's had a bigger cooler, in the Moonraker they were laid over on their sides.
 
Divemaster1 said:
At 6.9L, we could push out 485 Hp .... but current configuration is somewhere between 385 and 410 ... at a sedate WOT 2300 RPM

Your perkins are these the ones they later added an intercooler to and pushed up to 175 Hp?? ... used in the JCL Moonrakers etc.
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Alf,

Years ago I was blown away by how beautifully designed the DD strokers were, 1940's quality thinking. However using the link between displacement/power is a little tenuous for two strokes. Was also told by the DD guys that the 485 was a bit of a short life to overhaul rating.

Can I assume your 6V71's are say 1,236 kg dry for 410 hp. Modern 4 stroke motors in the 11/12 liter displacement node deliver 6/700 hp @ 2,300 rpm for less weight.

CAT C12 1,177 kg
CMD QSM11 1,125 kg
Scania D12 1,130 kg
 
Latestarter1 said:
...... Was also told by the DD guys that the 485 was a bit of a short life to overhaul rating.

Can I assume your 6V71's are say 1,236 kg dry for 410 hp. Modern 4 stroke motors in the 11/12 liter displacement node deliver 6/700 hp @ 2,300 rpm for less weight.
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Our engines are straight six's... so no V configuration ... correct label is 6/71 TIA.

Deliberately did not go for a boat with the "B" configuration as they have a bypass and rated at 2600 RPM and up to 485 hp... for the reasons you state in respect to reliability.

Take your point about the weight to HP ratio, but as I did not have any intention of pushing the 30 knot barrier and was going for an older boat with high displacement with abilit to keep reasonable speeds in rough sea, and with low maintenance cost, the DD's became a preferred option in the ranges we were looking...

If I were to change engines in our current boat, I'd be tempted by Cummins CTA's at 450 hp..., but would be woried about the boat's dynamics and how it would affect it's behavior at sea as I would loose about 1000 Kg...
 
virtuvas said:
so Alf,

fired up? tuned? working fine? audio clip of engines running :rolleyes: ?

V.
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Sorry about intermittent sound quality ...my blackberry is not the best video camera... (also interesting to see that valves and rockers are hardly seen as moving...).

So, 9 AM in a little tranquil society ....

http://s166.photobucket.com/albums/...tion=view&current=VID_00000-20120429-1001.mp4

... the silence was broken by ...

http://s166.photobucket.com/albums/...tion=view&current=VID_00002-20120429-1023.mp4

Which when Idle was adjusted and covers put on, looked like this ....

http://s166.photobucket.com/albums/...tion=view&current=VID_00003-20120429-1219.mp4

Happy camper now that all appears to be OK. Closed up, fixed furniture back etc.

Test under load will be done when I have sorted the cause of the need for that wooden plug ... , but for now she fire up straight away, idle at 500 RPM with no hunting and control up & down is good.... and most importantly she shuts down when I depress the stop button!!
 
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Divemaster1 said:
Sorry about sound quality ...my blackberry is not the best video camera... (also interesting to see that valves and rockers are hardly seen as moving...).

So, 9 AM in a little tranquil society ....

http://s166.photobucket.com/albums/...tion=view&current=VID_00000-20120429-1001.mp4

... the silence was broken by ...

http://s166.photobucket.com/albums/...tion=view&current=VID_00002-20120429-1023.mp4

Which when Idle was adjusted and covers put on, looked like this ....

http://s166.photobucket.com/albums/...tion=view&current=VID_00003-20120429-1219.mp4

Happy camper now that all appears to be OK. Closed up, fixed furniture back etc.

Test under load will be done when I have sorted the cause of the need for that wooden plug ... , but for now she fire up straight away, idle at 500 RPM with no hunting and control up & down is good.... and most importantly she shuts down when I depress the stop button!!
Click to expand...

Congratulations that was one serious job. Glad it had a happy ending.
 
Seahope said:
Congratulations that was one serious job. Glad it had a happy ending.
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Thanks!! Was worrying as I did not get rid of all air in the fuel system.... and could not get a clean fire, so re-primed a number of times.... that coupled with the fact that I did not manage a clean shutdown afterwards made me worry a bit, but both easily remedied within 15 Min... once brain was engaged ...
 
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