HSSK50 small block mods

delray

Well-Known Member
#25
did little porting and deburring on some casting flash on the block today. i just started to do some porting in the exhaust and then stop to take a picture show how small the entry was going into the port.
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intake need little work up above also
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block had a lot of casting flash that needed cleaning up.
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didn't go crazy on the porting just need the enter and exit areas rounded off little better. still not a big fan on the 5hp intake design. Really like go in and fill in couple spots with a good gas resistant epoxy material....will see? only going to be a 5000 rpm max motor. like make intake round and fill in the back bowl area so the air can flow up the bowl wall into the chamber better. just a poor design from the factory and you wonder why they only get 5hp out of this engine...LOL

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after getting all the flashing clean up and running the block through the hot tank it turn out good.
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delray

Well-Known Member
#27
ok guys, here is the cam i will be using out of a ovrm vertical engine. on a vertical engine they use a pump like system to force oil to the other end. so on a vertical engine this would be the top end of the cam. oil is pump through the center of the cam to help lubricate the bushing end. pump end of course is submerged in oil.
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ok here is the neat thing about this cam. they use a compression release on the back side of the cam gear. something you normally don't find on small block horz-engines. there was only one small block engine i have found before on a tecumseh-horz and that engine is kind of hard to find.
next to a vintage bump style compression cam.
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delray

Well-Known Member
#28
here is a good view to get little better idle how different the two are made on the front side of the cam gear.
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next step was to mount this in my 4 jaw and that wasn't working out they way i wanted it to be mounted in so the 3 jaw went back on the lathe and did some finessing with some shims and got it with in a .001...........good enough for me.
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first step was to knock off the vertical bearing surface.
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and then start to make the new bearing surface.
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part came out nice.
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hard part was to get the correct length from end to end and i got it.

stock vintage cam measurement
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new modified ovrm cam.
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and yes i do plan on using the tecumseh hot coil that will advance the timing a lot. making it just little harder to pull over when not using a compression release cam with it.
 
#29
When I was a kid back in the 70's I repaired mowers in my parents garage. I saw a few of those vertical crankshaft cams break, where the oil galley goes through the center. Nice machine work! just a heads up. Maybe you could press a shaft in there to strengthen.

Also thought highly of Tecumseh's compared to the splash oil system in briggs.
 

delray

Well-Known Member
#30
When I was a kid back in the 70's I repaired mowers in my parents garage. I saw a few of those vertical crankshaft cams break, where the oil galley goes through the center. Nice machine work! just a heads up. Maybe you could press a shaft in there to strengthen.

Also thought highly of Tecumseh's compared to the splash oil system in briggs.
interesting you say that. this ovrm cam seems to have little more material(casting) on the sides where the rod does not swing at. when i look at a flathead vertical cam it look to be little thinner. also this has a plastic gear molded on to the cast steel. not like the vintage cam where it was all steel. plastic may help absorb any unwanted impact to the camshaft. we will see and i also chamfered the holes little so oil can flow in from one side to the other good. hey this cam wasn't broke.....lol
 
#31
interesting you say that. this ovrm cam seems to have little more material(casting) on the sides where the rod does not swing at. when i look at a flathead vertical cam it look to be little thinner. also this has a plastic gear molded on to the cast steel. not like the vintage cam where it was all steel. plastic may help absorb any unwanted impact to the camshaft. we will see and i also chamfered the holes little so oil can flow in from one side to the other good. hey this cam wasn't broke.....lol
Maybe they did strengthen them. These were Toro mowers from about 1971 vintage
 

delray

Well-Known Member
#32
Maybe they did strengthen them. These were Toro mowers from about 1971 vintage
cam that i am using is from the 90's, something else i notes is the casting not has rough and porous casting has the vintage cams look to be. newer cam seems to have a smoother casting and more of a define casting line across them. maybe that too could a reason why newer stuff may not of broken. i will let you know when she's turning 5000 rpm's....lol
 

delray

Well-Known Member
#33
When I was a kid back in the 70's I repaired mowers in my parents garage. I saw a few of those vertical crankshaft cams break, where the oil galley goes through the center. Nice machine work! just a heads up. Maybe you could press a shaft in there to strengthen.

Also thought highly of Tecumseh's compared to the splash oil system in briggs.
another big problem i could see why the vintage cam's could break. look at the design how they made them. one the material was porous and rough and made out of cast steel and the big problem the distance was much greater between the bearing support. that had to put some kind of stress on the cam. maybe why you don't see the horz-cams breaking. the bearing support is much closer together making the cams more rigid.
 

delray

Well-Known Member
#34
here is another style compression release cam tecumseh made for a vertical engine. this one looks to have larger lobes so the lifters would have to be shorten and the compression release setup has a long rod extending to the rear or exhaust side. rod looks like it might get in the way of the conn rod on a horz-engine. this cam must use a straight up style rod where the rod bolts are on the bottom? something i would really need to look into first before saying for sure? either way i thought i would post it for all to see.
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delray

Well-Known Member
#37
here is another style compression release cam tecumseh made for a vertical engine. this one looks to have larger lobes so the lifters would have to be shorten and the compression release setup has a long rod extending to the rear or exhaust side. rod looks like it might get in the way of the conn rod on a horz-engine. this cam must use a straight up style rod where the rod bolts are on the bottom? something i would really need to look into first before saying for sure? either way i thought i would post it for all to see.
View attachment 273906
found out little more on this cam and it's a odd ball cam for sure. out of a newer flathead motor that does take straight/ tall narrow style conn/rod with the bolts on the bottom rod cap and has more teeth on the cam gear.
 

delray

Well-Known Member
#39
not much going on with my engine project. waiting for some new tooling for my hall valve refacer grinder. so then i can do my mods to stainless steel valves.
i did plug up the governor hole with a self tapping screw with little loctite. that was really hard....lol
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delray

Well-Known Member
#40
for my valves i'm going to replace the stock valves with some stainless steel valves. one of the reasons i'm going with them is the stems mic out at .248 and the stock exhaust valve is about .244 and it is very loose in the guide. with the .248 it fits real nice.
valves i had laying around from bunch extra parts i pickup in the pass. exhaust valve i believe is from a flathead briggs motor and the intake from a briggs animal or something?

first thing i did was make sure the length was correct and kept a extra .005 on the length so i can grind the tip down to the correct clearance when ready to install.
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next step was to cut the new grove for the valve so it will work with the dyno cam retainers/keepers
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turn out very nice. i still thinking of going back and cutting more material off the back side of the valve. maybe help the air flow little better in this area and the stem is already been cut down to 5mm. not really worrying about weakening the valve. i'm only running a 10.5 pound comp valve spring and the engine only going to spin max 5000 rpm's. might be little different if i was running a 36 pound and spinning 8500+ rpm's.....lol
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