Amal 376 Monobloc flooding

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Amal 376 Monobloc flooding

Postby illf8ed » Mon Jan 18, 2010 6:43 pm

Need some help from the Monobloc experts. Twin 376 Monoblocs...turn on fuel tap, both carbs flood from the center air passage hole at the intake side. I checked the floats and float height..everything is good - they shut off properly and have new viton float needles. I notice the jet blocks are not that tight in the carb body. Would some looseness here cause a floading issue? Looseness is with the jet holder removed. Also noted the screws that are supposed to hold the jet block in place, don't. I can remove the jet block with those screws turned in completely. Those are the symptoms...whaddya think docs?

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Re: Amal 376 Monobloc flooding

Postby grandpaul » Tue Jan 19, 2010 8:20 am

Monoblocs on a Commando?

Wouldn't the mounting angle affect the float level? Commando orientation (with stock manifolds) results in a bit of "downdraft" attitude.
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Re: Amal 376 Monobloc flooding

Postby Cookie » Tue Jan 19, 2010 10:46 am

Perhaps on his BSA? My G15CSR had monoblocks but I think it had a shortened float chamber on one side.
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Re: Amal 376 Monobloc flooding

Postby illf8ed » Tue Jan 19, 2010 12:55 pm

As far as I can tell there is no provision for adjusting the float level on a Monobloc. Regardless, the float and float needle seem to be working properly. I rigged up clear float bowl cover to see what's going on in there. I removed the jet block and jet holder then plug the hole with a rubber stopper then fitted a hose with fluid supply to the fuel banjo. Everything worked. When I refit the jet block and jet holder it floods.

Yes, the carbs are from the Cyclone, but I'm working on them from the bench with the body completely upright.

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Re: Amal 376 Monobloc flooding

Postby Cookie » Tue Jan 19, 2010 2:13 pm

David,

I wonder if this thread might get more attention over in the other bikes section? I'd think some of the guys like norbsa would have more experience with Monoblocs than Commando guys, you never know though who might own both.
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Re: Amal 376 Monobloc flooding

Postby illf8ed » Tue Jan 19, 2010 8:31 pm

Hi Cookie,

You're right. I was thinking Norton not just Commando. Norton used 376 Monoblocs on Dommi 88/99 and 650SS.
Switched to the other site.

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Re: Amal 376 Monobloc flooding

Postby kommando » Wed Jan 20, 2010 3:34 am

Are you putting the spacer on the float spindle after fitting the float, if not the float rides over the spindle and rubs against the cover reducing the upward pressure on the needle and the carb floods.
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Re: Amal 376 Monobloc flooding

Postby illf8ed » Wed Jan 20, 2010 7:32 pm

kommando wrote:Are you putting the spacer on the float spindle after fitting the float, if not the float rides over the spindle and rubs against the cover reducing the upward pressure on the needle and the carb floods.


Moved this over to other classics. To answer, yes the spacer is in place. The problem is not the float chamber, that works fine. The flooding is related to the jet block/jet holder area. My current action is to replace the gasket under the jet block and see if that stops the problem.

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