# Calling all NG16 Garratt owners



## main131 (Jan 3, 2008)

Serious owners of the impressive NG16 will have long since completed the modifications originally 'mooted' by Ron Blakeman whereby steam distribution was re-balanced more fairly between the two engine units.

Later observations also suggest that the O rings on the steam safety valves may have a tendency to flatten out or even occasionally split.

This is not a threatening health and safety hazard, but the continuous weeping gets worse with the higher the pressure and to achieve maximum performance you need to make sure that most of your steam goes into powering your engine rather than blowing into thin air.
Be sure therefore that your safety valves are set at 80psi, as recommended by the manufacturer.

You will note in the picture that the 'red line' painted on the gauge is compatible with the two valves blowing off.

As gauge readings can vary the setting is made separately by air pressure, so your 80psi red line will be where you have set it in accordance with your individual engine.You could of course do a professional test and put a line directly onto your safety valve and test under steam, but lets not go too far.


Obviously your engine will not be running at this pressure but rather 50 or 60 and that will give you the power you need to pull a heavy engine and twenty wagons or so. 
If the pressure is below this and assuming your water and gas are Ok then the chances are your on one burner which is simply not adequate. 
The problem with the Garratt is your view into the burners is obstructed by the front tender, but a flame on the chimney and a quick blow usually will ignite both burners. 

You will see on the video that my Garratt is very lively
http://youtu.be/W5X2896hEFQ









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## Chris Scott (Jan 2, 2008)

Which manufacturing run? #1 and #2 or run #3 with a number of improvements learned from runs #1 and #2?


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## Chris Scott (Jan 2, 2008)

Never mind. Looking at your photo more closely I can see your Garrett is from mfg Run #1 or #2. 

One of the improvements of Run #3, a small bridge piece was added over the cab doors connecting the rear and front halves of the cab. The rear portion of the cab moved or flexed quite a bit.


One issue on my Garrett, I believe yours too, merging the exhaust pipes from both engines into a single exhaust pipe going up the stack. The pipes are merged just below the fire box. All of the piping is 3mm including the single exhausted pipe going up the stack. I believe this causes a lot of back pressure limiting performance. I have modified this so two exhaust pipes go up the stack. Have not run it since the mod. First run will be at DH next week.


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## Dan Pantages (Jan 2, 2008)

Where can I find the modifications originally 'mooted' by Ron Blakeman ?


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## Shay Gear Head (Jan 3, 2008)

Dan,

Rod is usually in DH and you can ask him face-to-face.


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## Dan Pantages (Jan 2, 2008)

Sorry, I'm not going to be there. I will contact Rod about it.


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## main131 (Jan 3, 2008)

@import url(http://www.mylargescale.com/Provide...ad.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); Posted By Chris Scott on 14 Jan 2012 06:25 AM 


Never mind. Looking at your photo more closely I can see your Garrett is from mfg Run #1 or #2. 

One of the improvements of Run #3, a small bridge piece was added over the cab doors connecting the rear and front halves of the cab. The rear portion of the cab moved or flexed quite a bit.


One issue on my Garrett, I believe yours too, merging the exhaust pipes from both engines into a single exhaust pipe going up the stack. The pipes are merged just below the fire box. All of the piping is 3mm including the single exhausted pipe going up the stack. I believe this causes a lot of back pressure limiting performance. I have modified this so two exhaust pipes go up the stack. Have not run it since the mod. First run will be at DH next week. 

Hi Chris. let me know how you get on. Other folk have spoken of this problem.
If there is a marked difference I may well do the same as you.


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## topshed (Jan 20, 2008)

Hi, 
I have a black Garrett from the first run which, after some essential mods very kindly carried out by Accucraft UK, has always run very well, but slowly. I had always assumed the valve timing may be slightly out, but it may be there is another reason. I have had to change the safety valve O rings once, but one is beginning to leak again so that is a job that will need to be done again soon. Still a great engine though! 
Martin


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## Chris Scott (Jan 2, 2008)

Posted By main131 on 15 Jan 2012 08:22 AM 
@import url(http://www.mylargescale.com/Provide...ad.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); Posted By Chris Scott on 14 Jan 2012 06:25 AM 


Never mind. Looking at your photo more closely I can see your Garrett is from mfg Run #1 or #2. 

One of the improvements of Run #3, a small bridge piece was added over the cab doors connecting the rear and front halves of the cab. The rear portion of the cab moved or flexed quite a bit.


One issue on my Garrett, I believe yours too, merging the exhaust pipes from both engines into a single exhaust pipe going up the stack. The pipes are merged just below the fire box. All of the piping is 3mm including the single exhausted pipe going up the stack. I believe this causes a lot of back pressure limiting performance. I have modified this so two exhaust pipes go up the stack. Have not run it since the mod. First run will be at DH next week. 

Hi Chris. let me know how you get on. Other folk have spoken of this problem.
If there is a marked difference I may well do the same as you. 

It's not if, there will be a marked improvement in performance. The mod converts from a single 3mm exhaust up the stack or a 4:1 ratio (4 3mm cylinder exhaust merged to 1 3mm pipe up the stack), to 2 stack exhaust pipes or a ratio of 2:1. Gross benefit, halving of the exhaust back pressure. (Someone more sophisticated about these things may add some additional tech explaination(s))


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## rodblakeman (Jan 2, 2008)

Trevor, when I did the pipe modifications to your loco I made a new larger "T" connection for the exhaust under the smoke box so you should already benefit from a larger clearer exhaust.


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## Chris Scott (Jan 2, 2008)

Posted By rodblakeman on 15 Jan 2012 08:27 PM 
Trevor, when I did the pipe modifications to your loco I made a new larger "T" connection for the exhaust under the smoke box so you should already benefit from a larger clearer exhaust. 

Rod:
What sizes pipe did you use for the T pipe up the stack ?


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## main131 (Jan 3, 2008)

@import url(http://www.mylargescale.com/Provide...ad.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); Posted By rodblakeman on 15 Jan 2012 08:27 PM 
Trevor, when I did the pipe modifications to your loco I made a new larger "T" connection for the exhaust under the smoke box so you should already benefit from a larger clearer exhaust. Hi Rod 
Quite right so you did.
Could be the reason why I haven't had any steaming problems!


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