Briggs 18.5 twin specifications and hard to start when hot

sbklf said:

Oh thanks, should have posted it orignally:
Huskee 18.5 Twin Briggs Model #42A707 Type: 1238-01 Code: 9702065B

I was able to download a "Check Chart" with some information but not sure I am looking at the correct columns.
-Is my engine considered an L head opposed twin cylinder?
-For the L head opposed twin cylinder, they show Model/Series options 400000, 420000 and 480000 (?), would mine fall under 420000?

Thank you, Kevin

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sbklf said:

Hello from Houston,

I have a Huskee riding mower that I am working with an 18.5 Twin Briggs engine. I am just changing seals and gaskets to stop oil leaks, not sure which one is leaking so am changing all. The gasket kit came with different thicknesses of base gaskets for crankshaft end play adjustment (I am assuming). I measured before removing the base and was .017". What is it supposed to be?

What might cause the motor to be very hard to start after it gets hot? It seems if I adjust the throttle just right it might start back up 10% of the time but most of the time it wont, I have to let it cool first. I thought it might be the coil because the spark seems weak but the guy at Als says the coils either work or they dont, no inbetween.

Thanks, Kevin

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EngineMan said:

question 1 yes it is a L head, question 2 that is the right column it should read 400000, 420000 and 460000

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nbest said:

This sounds to me like the coil is going out. Heat increases the resistance so when the engine is hot and it is starting at a low speed it doesn't have enough voltage to overcome the resistance. You can test this by checking for spark the next time you have a problem. If it produces spark when grounded to the frame, but not to the plug, then the problem is the coil.

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sbklf said:

Hello from Houston,

I have a Huskee riding mower that I am working with an 18.5 Twin Briggs engine. I am just changing seals and gaskets to stop oil leaks, not sure which one is leaking so am changing all. The gasket kit came with different thicknesses of base gaskets for crankshaft end play adjustment (I am assuming). I measured before removing the base and was .017". What is it supposed to be?

What might cause the motor to be very hard to start after it gets hot? It seems if I adjust the throttle just right it might start back up 10% of the time but most of the time it wont, I have to let it cool first. I thought it might be the coil because the spark seems weak but the guy at Als says the coils either work or they dont, no inbetween.

Thanks, Kevin

Click to expand...

Glenny65 said:

I've heard people say that for 40 years, that a coil either works or doesn't. That is simply untrue. Coils can "fade" with time and cause problems when temperatures get too high. Everything from these opposed 180 Briggs engines, up to my 65 Ford Fairlane....(I always knew when my coil was about to go out because when I increased my rpm's it would start skipping. Fact is, (and you can google it too) the Briggs opposed engines are awesome in power/torque and smooth running, but they eat coils up pretty quick. Personally, I think it's because they fire twice as often as normal coils, but doesn't just cut the life in half, but by much more, since the double firing increases the heat. It was a bad idea, but aside from that, those engines are terrific. About the only thing you can do is make sure you set your air gap correctly...should be .010". And shine the surfaces that meet, both on the engine and the coil. This is to help the coil dissipate heat better. Also make sure the fins are clear of debris.....anything else you can think of to decrease heat from the engine.

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