Old Flywheel - new short block - spark timing way out ?

[Scottishlad]

Calling for help all the way from the Scottish Highlands!

I recently bought a "spares of repair" ride on from a friend with a 15.5 HP BS intek engine which had thrown a con rod, through lack of lubrication. After assessment I reckoned that a new short block was the most economic fix.

This arrived Friday and i built it up over the weekend with all the old parts transferring without (apparent issue) ... however she wont fire up ....

I checked for spark and fuel and all looks good / valve clearances set (4 thou for inlet and 6 exhaust). 12 thou air gap at flywheel /coil interface

Checking valves clearances again this morning I set TDC with a screwdriver in the bore and just before checking valves I noticed that my flywheel magnets are almost 90 degree behind where I'd expect them to be ( I assume that the magnet and the coil should be more or less in alignment?

(also realised that the exhaust / muffler was noticeably warm despite the lack of running - id put this down to just the compression of the gas but suspect now that I had combustion but just not at the right time.....

Checked the flywheel key way and key and all in alignment with the crank (no sign of damage etc)

Looks awfully like my original flywheel and the new crank are not a match?

My original engine is Model 31 A6 07 Type 01 26 B1 080818ZD

New short Block is Serial 2109028139679 Model 592059A

I'm hoping that if I'm right then Briggs will take the block back or send my a new compatible flywheel ....

Questions -

Where should the flywheel magnet be with respect to the two legs of the coil at TDC ?

Can anyone help to confirm my diagnosis (or provide other hints)

Thanks in anticipation

 

[Scrubcadet10]

do you still have access to your old (original flywheel)? i would take both flywheels, and line the key ways in them up, and see if the magnet is in a different position

 

[StarTech]

Back in 2013 Briggs changed the flywheel and crankshaft key ways. In order to repair a 2008 model with 2021 short block there two ways either you clean up a usable crankshaft and install it or you install the new flywheel. But Briggs will not send you a free newer flywheel or a free older crankshaft. Of course using the old crankshaft if good is the cheapest route as you only need a new sump and rocker gasket (RTV on some engines).

Now a new flywheel will sit you back $185 retail.

 

[Scottishlad]

Back in 2013 Briggs changed the flywheel and crankshaft key ways. In order to repair a 2008 model with 2021 short block there two ways either you clean up a usable crankshaft and install it or you install the new flywheel. But Briggs will not send you a free newer flywheel or a free older crankshaft. Of course using the old crankshaft if good is the cheapest route as you only need a new sump and rocker gasket (RTV on some engines).

Now a new flywheel will sit you back $185 retail.

Thanks for that … as Briggs were given the engine code details when I ordered the short block should they not point out the incompatibility between old and new ? By the time I buy another flywheel I’d have been as well to buy a complete motor and save the time rebuilding …. The old crank was wrecked by the failed Con-rod

 

[Scottishlad]

Thanks for that … as Briggs were given the engine code details when I ordered the short block should they not point out the incompatibility between old and new ? By the time I buy another flywheel I’d have been as well to buy a complete motor and save the time rebuilding …. The old crank was wrecked by the failed Con-rod

Also wonder if I could get a machine shop to cut a new jetway in the fy wheel if I knew the position ? Presumably it wouldn’t weaken it any more than the existing one ?

 

[Scottishlad]

do you still have access to your old (original flywheel)? i would take both flywheels, and line the key ways in them up, and see if the magnet is in a different position

Hi and thanks for your reply … I’ve no new flywheel as the short block is just the crankcase and internal parts. It seems from another reply that the flywheels are indeed different … only wish Briggs had told me before I ordered it!

 

[ILENGINE]

Briggs has a special note for shortblock replacement

Shortblock Notes​

• Engines Built Prior to 07/12/2012 should use short block 697761. Engines built on or after 07/12/2012 should use short block 592059.

And it appears that the 697761 short block is no longer available.

 

[StarTech]

Briggs has a special note for shortblock replacement

Shortblock Notes​

• Engines Built Prior to 07/12/2012 should use short block 697761. Engines built on or after 07/12/2012 should use short block 592059.

And it appears that the 697761 short block is no longer available.

Correct according to Power Distributors it is NLA back at the first July it was but that has changed now and only the 592059 is available.

 

[Elkins45]

Also wonder if I could get a machine shop to cut a new jetway in the fy wheel if I knew the position ? Presumably it wouldn’t weaken it any more than the existing one ?

That would be the route I would try. You could probably do it yourself with a file if you knew the correct position.

 

[Scottishlad]

Correct according to Power Distributors it is NLA back at the first July it was but that has changed now and only the 592059 is available.
View attachment 62692

Many, many thanks for this ! That's an excellent bit of information .... it may be that I can use this to return the incorrectly supplied shortblock or get them to give me a new flywheel compatible with the newer engine keyway ... the risk with that is that i'll then discover that the diameter of the new flywheel is different so i'll need a new coil too or that the starter ring gear is a different profile and I'll need a new startermotor.....Aargh!