Briggs Stroker Build

Hey guys i've recently started a build that i haven't really ever seen done before. Others have talked about it but i've decided to do it. I'm building a stroker out of an 11hp(model25) block and a 12hp(model 28) crank. Like I said I'm in the early stages of the build so i've done mock up and some clearancing.

Keep us posted, and include as many pics as possible. Good luck!

Ah yes, glad to see you here! yea if you have a computer post some pics up.

Heres how to: https://www.atltf.com/t1525-image-posting-for-new-members

once clearanced, how do you plan on closing it up again, out of curiosity? weld? plate?

This is gona be sick keep us posted   

Minor progress this weekend. Stripped all grease, grime and paint and began some simple mods. Teaser for a cam idea. Drilled and tapped the block around the gaping hole. More pics to come around Wednesday. Hopefully with a shaved piston and sized head.

WOW that piston has some above the deck height... any plans on shaping the piston head? or are you leaving it flat?

I'd be afraid to take that much off a piston crown. I can see blowing a hole in it. Shorter rod, methinks. Do I see porosity in the cam lobes?

Id leave that piston how she sits and clearance the head by cnc-ing it out. Or go 50/50 on the head an piston. Looks good! If I had a 11hp, i'd make one.

I was thinking profiling to promote swirl in the chamber. I will admit that the proximity of the ring grove to the deck height is concerning me... when the rod heats up, and "Grows" I'm concerned it may actually protrude past the cyl itself... Time will tell.

I was planning on going 30/70 on the head and piston clearance. (More from the head). If it does have a ring problem then a shorter rod is in the future. As for the cam, I ran it in a stock motor today and it was very torquey on low end. Hoping to do this cheap but if need be, I can get the necessary parts.

Does it help having the cam lobes more square? Or is that so it opens sooner

Interesting project you have.  I am very curious of how it turns out.
several years ago i was building up a old cast iron 16hp briggs for a puller project.  I was going to use a motorcycle carburetor and a custom made ignition.  To up the compression i machined a head out of a chunk of 1.5 inch thick aircraft aluminum.  The head never got finished, all it needed was the spark plug hole finished.  I made the head so the thickness of the gasket was all the clearance there was between the top of the piston and head.  One thing i was going to do was to put the spark plug directly above the exhaust valve.  I got that from some of the big time Kohler builders.  the reason for it had to do with the fuel mix wanting to go to the hottest spot in the cylinder.  And the hottest spot in the cylinder was the exhaust valve.  Really i don't know and all that's over my head but i did it any way.  Any way maybe this would give you some ideas.

Daniel

The exhaust lobe is more square in the idea of keeping it open longer. Goesman, I would have loved to see that build finished. That looks sweet.

Neat to try stuff out with cheap parts. Should be interesting. If you think that the upper ring might be a problem, maybe just run the compression ring in the scraper ring groove with the top groove left empty. If I had an aluminum welder, I'd be cutting up engine blocks all the time.

interesting build. ill be very interested to see how it turns out because I do have a spare 25 c.i. sitting around.

Sorry for the lack of updates. The build is still in progress but there was some difficulty finding time to get the machine work done. With spring break around the corner I promise an update with more progress made.

i like watching thireads like this, its neat to see the stuff people are building when its like this, not just a plain build or work on

very cool, keep us updated

I'm not sure if you thought about doing this, but you can grind the side of the cam off on the backside, opposite the lobe, then add some length to the tappet to make up the difference to increase the valve lift. Basically you're making the base circle of the cam smaller like they do to get really high lift cams in a car engine because you're limited to the area the cam has to work in.