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16hp Briggs starting problem


osenga

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Just rebuilt a 16hp Briggs (326431) and all put back into timing and all new gaskets. And got really hot spark to. This has good compression. So here is what problems I have when the plug is out it cranks over great. When I put the plug in it don't want to crank over. I am lost now. I have tried 8 different S/G same thing on all of the 3 different battery's one was my trucks while i had (truck) running and nothing. I have made up a wiring harness to use a push start on it and also have just used jumper cables. All the same results. If anybody has any ideas to get this running this will be great.

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Crank over as in won't go through a stroke? Or crack over as in spark when threaded in?If its the 1st: Milo might be right? someone may have messed up the depth? I doubt it though2nd: To spark when threaded into the hole it needs to be grounded, maybe the threads are so covered and head bolts that your not getting a good ground from block through head to plug?Ronald is dead on too! I have overtightened belts and it pulls the mag out just enough to mess up the ignition. Re-Gap mag accordingly. Better little loose on the belt (they are way cheaper than bearings :P )

quote:Originally posted by bigten65

spark plug hitting the top of the piston?


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Well I say good compression because on the up stroke of it. It does get stiff to turn flywheel by hand can't check it because if plug hole is plugged it won't turn over with a battery and rope start it wants to take my arm off. And piston not hitting the plug .

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Too much clearance on the intake valve. Should be .008 for the de-compression bump on the cam to work. Just a guess on my part, but

if it is rolling over with the plug out there should not be any other mechanical problem.

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Jim, you and I had the same idea. You just beat me to it. Valve clearances are something that get totally overlooked quite often. Too loose must be from a rebuild. The valves usually get tighter from wear.

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Well neve touched the valves. But they are all moving and for what I can see they are seating good. And new rod rings piston

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quote:Originally posted by dhardin

Your cam is 180 degrees off.


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id="quote">I was thinking he is going to have to open it back up .
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Bryan it DOES sound like valve timing to me too... or just a weak battery. put a volt meter on the battery or starter solinoid while cranking (or trying to crank) and see if the voltage drops way below 12...if good it shouldn't have a big voltage drop....otherwise...valve issue is my guess

Good luck!

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Well for the battery I can't see it being weak it starts my truck every day and had the truck running. And it was a S/G . And my crank (/) mark lines up to the (•)

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Do the voltage drop test at the starter terminal for + lead on your meter and on the battery for - lead.

If it drops while trying to crank it then there IS a problem in the starter curcuit. If no drop then you can rule out any electrical trbl on the starter circuit. My guess is you'll get a drop. Do you have a solinoid or starter button? cruddy contacts or wire anywhere in the curcuit can cause a voltage drop.

A healthy circuit will stay around 10-12v while cranking.

sm01

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quote:Originally posted by osenga

Well for the battery I can't see it being weak it starts my truck every day and had the truck running. And it was a S/G . And my crank (/) mark lines up to the (•)


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id="quote">well that sucks bryan about the engine. did you bypass everything and try jumper cables directly to the S&G post ? . if you did not touch valves or cam then i cant see it being anything internal . do you have trans fluid in the cylinder to lubricate/set the new rings ?.
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"It does get stiff to turn flywheel by hand can't check it because if plug hole is plugged it won't turn over with a battery and rope start it wants to take my arm off.

Is it attempting to backfire when you use a rope? If you had the mag off while it was apart, you might not have put it where it is supposed to be, and though everything else seems right, you are still out of time. The holes in the mag are slotted and oversize. If the points don't trip to fire at TDC, you get the backfire that will pull your arm out of joint

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I think he is in a cranking problem now not an ignition issue, it wont crank over at all using the starter with the plug in (w/compression pressure) so if not electrical then its mechanical, like valves again. Perry had a good point about new rings draggin? trans fluid in cyl? cant wait to hear more,,,good luck Bryan

quote:Originally posted by MrSteele

"It does get stiff to turn flywheel by hand can't check it because if plug hole is plugged it won't turn over with a battery and rope start it wants to take my arm off.Is it attempting to backfire when you use a rope? If you had the mag off while it was apart, you might not have put it where it is supposed to be, and though everything else seems right, you are still out of time. The holes in the mag are slotted and oversize. If the points don't trip to fire at TDC, you get the backfire that will pull your arm out of joint


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I think he has a different problem he said it gets stiff when turning over by hand I wonder if he left the groove in the top of the cylinder and the new piston and rings are having to compress to get over the groove

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Put a compression gauge on it to find a value. I have a 3112 w/ 16HP engine that still puts out 110 PSI and it is done with SG.

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Bob can't do a compression test that I have to plug off the hole. While plug is out it cranks fine with S/G and soon as I put even my thump over hole it stops cranking. And no groove in the cylinder walls for rings to get over

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Seems like everyone has an opinion on this one, so I'll throw in mine. If just putting your thumb over the spark plug hole will make it so it won't turn over, then it's not a timing problem, my guess is the starter generator. As they say in the dealer shops, replace with a known good unit. If you are jumping it with your truck, could be bad jumper cables or connection, but I assume you have already looked at that.

Keep us informed on progress, you got my curiosity up now.

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