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Briggs 300 series valve clearance

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Can't seem to find any valve clearance specs (OHV) or service manuals for these newish Briggs lawnmower engines. Any help / tips appreciated. Difficult to start because primer not doing its job - pulled it out & white ring badly distorted so I guess it wasn't making the seal needed? New bulb & ring ordered.  (Fires first time with a squirt into the carb directly so am assuming the distorted plastic ring was breaking the air seal needed to suck fuel?)

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Mike. Inlet valves 5-7thou, Ex valve 7-9thou.

The primer does not suck fuel on these engines, it applies some pressure directly into the carb float chamber which pushes down on the fuel level, which in turn squirts some up into the carb throat.

The bulb needs to seal in its housing, and the housing needs to seal against the carb or some pressure can be lost.

Also, if the primer is in the housing, as I suspect, rather then the remote type, some pressure can be lost through the little white hose tail on the right of there carb, just above the fuel hose. This hose tail can be removed and sealed by melting the tip with a lighter flame (do it away from the carb) before reinserting into carb. 

The tail is just there for when remote primers are used and the pump pressure pulse is fed to this tail by a pipe.

Hope this helps

 

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9 hours ago, GardenKit said:

Mike. Inlet valves 5-7thou, Ex valve 7-9thou.

The primer does not suck fuel on these engines, it applies some pressure directly into the carb float chamber which pushes down on the fuel level, which in turn squirts some up into the carb throat.

The bulb needs to seal in its housing, and the housing needs to seal against the carb or some pressure can be lost.

Also, if the primer is in the housing, as I suspect, rather then the remote type, some pressure can be lost through the little white hose tail on the right of there carb, just above the fuel hose. This hose tail can be removed and sealed by melting the tip with a lighter flame (do it away from the carb) before reinserting into carb. 

The tail is just there for when remote primers are used and the pump pressure pulse is fed to this tail by a pipe.

Hope this helps

 

That's an ace explanation  Barrie - I was wondering what that white tail was - thank you. So, pressure in the float chamber forces the fuel up the jet (cartridge) into the throat where it gets sucked into the cylinder by the turning over of the engine.

 

I was a bit confused because I've mostly worked on L Heads where clearances are specd differently - inlet/exhaust - from what I could see for other OHVs they seemed to be set to the same? 

 

Thank you

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