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Any help appreciated. I have a briggs 28Q777-0678-E1. This is a 2000 15HP engine on a Dixon ZTR. The recommended short block is 697762. However, even though everything fit up great, reworked carb, lapped valves but the thing wont run. The SB fits model 28 and 31 Briggs engines, and the parts list show same flywheel, valves, head ect. for both series. :confused2:But it just sputters and back fires. Seems like it has the wrong flywheel, but that's not what the parts listings say?? I am stumped!

When you replaced the flywheel on the new short block, did you get it torqued to specification. If not there is a chance that the key has sheared and that is what is causing the no start situation. Either that, or the valves aren't adjusted properly

Back to basics, Stop and think. All you replaced is a short block, so you are using all the old components to run the engine. Start with do you have a good strong spark, are you getting a healthy supply of fuel and air, (no vacuum leaks) Check the compression, is the cam and ignition all in time????? Just how did the old engine run? Some times you just have to back track a little.

reynoldston said:

Back to basics, Stop and think. All you replaced is a short block, so you are using all the old components to run the engine. Start with do you have a good strong spark, are you getting a healthy supply of fuel and air, (no vacuum leaks) Check the compression, is the cam and ignition all in time????? Just how did the old engine run? Some times you just have to back track a little.

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Old engine ran good until last spring when it began smoking, and loosing power. Pulled head and could see scaring. Decided to get a few more years and go with a short block rather than rebuild. Maybe that was a bad decision, but it is done now. It is a brand new SB so I did not go into the engine to see if the cam marks were aligned. I took it for granted Briggs should be able to do that right. Tank was removed and gas completely drained. Carb cleaned, actually twice. New key installed and tightened to 100#. Old key was worn, but flywheel looked to be lined up. I used the old head, and push rods. Just cleaned them up. Reinstalled and set valves to spec at 1/4" past TDC. I don't remember the spec #'s. From Briggs though. Still would not start. I had to travel, so a friend pulled the head and lapped the valves. I did not witness his work, and I have not done a light test to see if the valves are seating properly. So that is one unknown for me? He did say the push rods looked too worn. I do remember some marking on one rod, but at the time I did not think it too bad? I do remember he did a compression check and said the valves were holding. The compression on the new block is very good. Checked spark with a tester and placing plug against head. Shows OK spark. Good fuel flow to carb. I have even tried start fluid. This should be simple, but it isn't. I think the problem is in the valves/head, but my friends think the flywheel is wrong for that SB. But that's not what the parts manuals show? All interchangeable.
Thanks for the replies guys.

short block isn't a mistake. I always have good luck with them. Spark, compression, fuel, timing you are missing one of them or it would run. Anything I can tell you on a forum is just a guess on my part. Can the coil go in more then one way like upside down? some of the Briggs engines that can happen very easy, I know because I have seen it happen and the engine wouldn't run.

"Leak-Down" test can tell if your valves are leaking past the seats.

But should still run, even if they are leaking somewhat.

Kinda sounds electrical in nature.

Did you check for a sheared flywheel key as ILENGINE suggested. To me that would be the first thing you need to check.