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Discussion Starter · #1 ·
I recently purchased a "new style pop valve w/adjustable pressure release" from Accucraft (AP-21103) intending to use it on my Mogul. It certainly works, but not as I expected it to.

It came adjusted to pop at about 80psi. It can definetly be adjusted lower. But regardless of what it's adjusted to, when it pops it consistently dumps a full 40psi. Is this the way it is supposed to work, or did I get a faulty one? I had expected it to dump maybe 10-20psi then shut off, not dump my entire head of steam.

[I know how to adjust the high pressure setting... but don't see any way to affect the low pressure setting.]

Thanks,
Joe
 

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Discussion Starter · #8 ·
Posted By ETSRRCo on 08/27/2008 6:54 PM
So do all Accucraft pops have this problem? Joe how hard was it to put the pop on the mogul?

I gave Cliff a call. As always, he was very helpful. He quickly agreed that the pop-valve that I received is clearly faulty, and he is going to pull and bench test a replacement for me (pop at 75, close 65-70). Per Cliff, it should only dump 5-10psi max before closing. So apparently my faulty pop-valve is not the norm, but also not unheard of.

Since he's sending a replacement, I'll go ahead and pull the bad one apart and see if I can find a replacement ball for it as an experiment.

Installing the pop-valve is a breeze. On the mogul, you first have to remove the one bolt that holds the whistle arm to the whistle. Once that's out of the way, the entire steam dome unscrews. The pop-valve is inside and just screws into the boiler. I had to use a pair of pliers to loosen the original; I didn't tighten the replacement quite as much since it has an O-ring and seals well with light pressure.

It does take a special tool to adjust the pop point. I machined one from a cheap flat-blade screwdriver using a dremel tool with a cut-off weel. Took maybe 10 minutes to make. But it's quite possible that a new pop-valve will come factory set at a reasonable pop-point and won't need any initial adjustment at all, so that tool might be optional.

Joe
 

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Discussion Starter · #11 ·
Posted By ETSRRCo on 08/28/2008 5:06 PM
So the dome just screws off? Might be a dumb question but I just bought my mogul second hand and all it had was boiler certificate and gas tank certificate. I tried unscrewing the dome but it wouldn't budge.

-Eric



The domes are notorious for being tight. Yes, they just unscrew at the base (after you've removed the whistle handle so it doesn't get in the way).




You might want to consider first unscrewing and removing the whistle itself just for safety's sake. So if you slip or get a bit aggressive while breaking the dome loose, you won't accidentally snap off the whistle at it's base. [Been there, done that. /DesktopModules/NTForums/themes/mls/emoticons/sad.gif ] It should only be finger tight and should unscrew easily.




Joe
 

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Discussion Starter · #13 ·
Posted By weaverc on 08/28/2008 5:21 PM
Eric,
I don't know about the Mogul, but my K-27 has a screw-off dome and my K-28 has one little allen set screw to release the top half of the dome, which then lifts off. I had to use a flashlight to see the set screw on the front and not on the side of the dome about half way up.



There is no set screw on the Mogul's dome; just screws off. (At least not on mine.)

Joe
 
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