1 1/2 HP FBM

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Geochurchi
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Re: 1 1/2 HP FBM

Post by Geochurchi »

No cam shaft or lifter involved.
If it ain’t broken keep working on it until it is .
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Bill Shields
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Re: 1 1/2 HP FBM

Post by Bill Shields »

so...what is supposed to move the intake valve?

there appears to be a lot of mechanical linkage there sitting on top of the valve stem.

I may be calling it by a name which may not apply to the older 'design specs'...but SOMETHING has to make the valve go up and down....

i guess that I am missing something (again....)
Too many things going on to bother listing them.
Geochurchi
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Re: 1 1/2 HP FBM

Post by Geochurchi »

Intake valve opens by suction only as far as I can tell, I did a vacuum test with a fabricated vacuum gauge on the intake manifold and I had suction, next step will be to remove the spring on the valve and see what happens then.
Is the trip arm on a Bosch AB33 mag adjustable?
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
Chris Smith
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Re: 1 1/2 HP FBM

Post by Chris Smith »

It does work by suction. Exhaust has the cam. Mine is a 7.5 hp Type Z.

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Bill Shields
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Re: 1 1/2 HP FBM

Post by Bill Shields »

Ah...ok

I would look for leaks back into intake manifold...
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Bob D.
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Re: 1 1/2 HP FBM

Post by Bob D. »

The intake is called an atmospheric valve. Not so much suction but atmosphere pressure pushing it open. To function, it must be freely moving and both the exhaust and intake valve seats have to be sealing. Also at hand cranking speeds you will not see much movement of the valve stem. Only opens enough to equalize pressure between the cylinder and the atmosphere.
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Geochurchi
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Re: 1 1/2 HP FBM

Post by Geochurchi »

So how does an atmospheric valve relate to getting fuel into the cylinder, the valve does move freely and both have been refaced, I am going to remove the valve spring and see if there is any action of the valve, could be the wrong spring, who knows.
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
Bob D.
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Re: 1 1/2 HP FBM

Post by Bob D. »

So when were the valves done? Were they lapped and checked for contact? This motor hasn't run in ages. All it takes is a piece of crud to hang things up. Has the same function as any other intake valve other than the manner which it is operated….
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
Geochurchi
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Joined: Mon Feb 22, 2021 7:49 am
Location: Concord ,NH / Naples, Fl

Re: 1 1/2 HP FBM

Post by Geochurchi »

E47B37C7-D4DE-4808-AC9C-55A7BB90482A.jpeg
Valves were done a couple of years ago using an electric drill and valve lapping compound, more to clean things up a bit.
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
Bob D.
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Re: 1 1/2 HP FBM

Post by Bob D. »

It looks like you cleaned up areas that don't matter on the exhaust valve. If you spun the valves around with an electric drill and lapping compound that may well have caused a problem. That makes seat to valve contact area wallow out and doesn't make a mating surface. It is done by hand with only a 1/4 turn oscillation, not a rotation. Did you even remove the valves?
Are you still getting gas everywhere when cranking it over?
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
Geochurchi
Posts: 153
Joined: Mon Feb 22, 2021 7:49 am
Location: Concord ,NH / Naples, Fl

Re: 1 1/2 HP FBM

Post by Geochurchi »

Took the valves out, that pic is pretty much the way it looked when I removed the head ,no gas getting anywhere .
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
Bob D.
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Joined: Thu Jun 21, 2012 10:43 pm
Location: Saco, ME. USA

Re: 1 1/2 HP FBM

Post by Bob D. »

Well, a year ago you had gas everywhere and since then you rebuilt the carb again and have no fuel anywhere…. I'd be looking at the carb again. Is there fuel in the bowl? Did you check and set the float level? As far as ignition timing I believe it is set entirely by the point gap which should be .015”.
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
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