23h briggs and stratton wont crank past compression stroke

christiansenApril 8, 2012

i have a 23h briggs model 446777 type 0264e1 that wont crank past compression stroke any ideas? i put a new starter on it did not fix it. tryed jumping it from the battery right to the starter still no better. battery has 230 cold cranking amps. i ajusted the valves at .004 at top dead center is this right? but still no better. i can take the plugs out and it cranks like crazy. and if i start it with a drill it runs great. any ideas??? please help

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tomplum

You are OK @ .004, but make the adjustment at the point that the piston is 1/4" past tdc. Then report back.

    Bookmark   April 8, 2012 at 11:54PM
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christiansen

ok will do thank you

    Bookmark   April 9, 2012 at 12:05AM
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christiansen

well that did not fix it. but maybe my new starter is not as strong as a factory one cuz i got it off ebay and it is about 1/2" shorter then my old one? or dose my engine have compression release? if so how can i tell if it is working?

    Bookmark   April 9, 2012 at 9:24PM
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tomplum

Yes, your engine has a compression release. You will need to know that the valve train on the upper end. Rocker studs tight, guides back in their holes , push rods straight. You can see the compression release cause a bump in the intake valve. It holds the valve slightly open to release some compression.

    Bookmark   April 9, 2012 at 10:31PM
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rustyj14(W/PA)

Just because the battery sez it has all of those "cold cranking amps" does not indicate if it is fully charged. If it spins the engine with the plugs out, but not with them in, i'd look at how much of a high charge is left in the battery. Use a meter that checks the charge left in the battery. Did you have it out? Did you recharge it lately? Do you have any way to check if it is charged enough to turn the engine to make it start and run? And, don't forget: Red is positive, to the solenoid and black is negative ground to the frame, or engine block

    Bookmark   April 11, 2012 at 12:40PM
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rcbe(6)

Ditto Rusty's observations. Would also remove battery; take same to qualified shop that can run a LOAD test.. and while that battery is out, use a pc of sandpaper or emery cloth to clean all electrical connection points to bright mental - including the ground connection to the frame. Any corrosion buildup at those points will act like a resistor reducing battery power to your starter. And all corrosion is not visible to the eye - use the sandpaper.

    Bookmark   April 11, 2012 at 1:00PM
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BriggsGalaxieman

Let me chime in here....I have three of the Briggs 446777 engines. Have rebuilt them totally. I could be wrong, but I don't think that the 446777 engine has any 'compression release' mechanism.

    Bookmark   April 14, 2012 at 6:36AM
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walt2002

"Let me chime in here....I have three of the Briggs 446777 engines. Have rebuilt them totally. I could be wrong, but I don't think that the 446777 engine has any 'compression release' mechanism."

It doesn't have a compression release "mechanism". As is typical of many B&S engines it utilizes the "easy Spin" cam grind which holds the Intake Valve slightly open well into the compression stroke. Not something you would notice when dismantling/re-assembling.

Walt Conner

    Bookmark   April 14, 2012 at 8:35AM
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walt2002

As a follow up, you need to check that the compression release is taking place as described by tomplum above except my experience is it doesn't actually "bunp" just does not completely close until very late. You should see a very slight final movement to closed. IF you do not see that when the valves are adjusted properly, then likely the camshaft is bad.

Walt Conner

    Bookmark   April 14, 2012 at 8:41AM
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rcmoser

Is this briggs only idea? IF so it cheapens the brand and IMO that easy spin/starting feature will be the down fall of Briggs and stratton. Most people don't or won't do the required adjustments after few years to keep these engines running. Therefore IMO they will probably not buy that brand again.

IMO they only designed that to allow cheaper parts to start the engine. Just like ex employee claim the .15 part to fix trigger in certain brand of firearm to prevent discharge when dropped or bumped 50 years ago. Cuts into the CEO's millions dollars of bonus and they can't have that.

    Bookmark   April 14, 2012 at 8:58AM
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BriggsGalaxieman

"It doesn't have a compression release "mechanism". As is typical of many B&S engines it utilizes the "easy Spin" cam grind which holds the Intake Valve slightly open well into the compression stroke. Not something you would notice when dismantling/re-assembling. "

Thanks Walt...now I understand the compression release on these engines...

    Bookmark   April 14, 2012 at 3:44PM
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mownie(7)

The Easy Spin design is actually brilliant in its simplicity.
It exploits the fact that at cranking RPM (relatively slow) the slight bump will allow enough time for compression to release past the slightly unseated valve, and that will permit the starter to "get the flywheel spinning" easier.
As the flywheel begins to spin up, the volume of compression released decreases because the camshaft is now moving the "bump" past the tappet at a faster pace, so the compression has less time to leak out.
When the engine has spun up to operating RPMs, the amount of compression released is virtually nil, because the bump passes the tappet so quickly.
The amount of time for compression to actually release is directly proportionate to the RPM of the engine. The slower the RPM the greater is the time the bump actually spends in contact with the tappet.

    Bookmark   April 14, 2012 at 4:12PM
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walt2002

"Is this briggs only idea? IF so it cheapens the brand and IMO that easy spin/starting feature will be the down fall of Briggs and stratton"

Easy Spin Cam Shaft has been used by B&S for more years than I know. It was used on flat head engines and as Mownie above says, it is simple and works. Another reason it has minimal affect at operating speeds is because of the "lag" of the incoming air trying to catch up with the piston. Partial vacuum in other words as the piston speeds up.

Walt Conner

    Bookmark   April 14, 2012 at 4:55PM
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baymee(LehighValleyPA)

Here is a compression release feature from a 6.5HP Briggs. At start-up, the "bump" is upward and slightly opens the valve as the cam goes by. The weight is close to the camshaft. As the speed increases, the weight opens up as shown with the screwdriver. At the same time, the bump is turned sideways and no longer affects the valve.

    Bookmark   April 14, 2012 at 6:52PM
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walt2002

This is the compression release which does utilize a "mechanism" as opposed to the "Easy Spin Cam" we are talking about.

Walt Conner

    Bookmark   April 14, 2012 at 7:18PM
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EricBarney

And I thought BMW's valvetronic engine managment was impressive!!

    Bookmark   April 18, 2012 at 8:54PM
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