HSSK50 small block mods

delray

Well-Known Member
#81
I recently bought a .010 Tecumseh piston (40045) that had that coating on it....at the machine shop the machinist stated it could withstand tighter tolerances....I don’t know, it sounded good....
note sure on the tighter tolerances on a air cooled engine. maybe on a car engine where the temp is controlled better. one thing i do like about the coating on top of the piston. it definitely helps control heat on my race engines and keeps the piston from expanding in the bore and damaging the piston skirt and the black micro coat helps also.
I have LH 195(hs-50 sm bore) and that came with a coated piston. also note the design is different then my hssk50
lh 195 3.jpg

numbers on the side cover.
lh 195 2.jpg

when you look up the numbers i see the 40045 as the .010 piston rings.
LH 195.PNG
 

markus

Well-Known Member
#83
The 40045 is technically a .010 oversize piston assembly for the LEV120's 40007 is the true updated # for .010 rings only. No idea why the parts listings are listed that way if it was intentional or a mistake (they do use the same rings). A .010 over piston assembly for the HS/LH is the 40005a.

As stated previously by me Tecumseh lit shows that they going to the elliptical pistons with T coating rather than the usual chroming in 2005 on the small frames based of the LEV120 piston design to reduce blow by and decrease friction etc... Based off though, not just using those pistons. Which is why I was curious of Skipp's findings an comparisons to an actual HSSK/LH piston.
 

delray

Well-Known Member
#85
The 40045 is technically a .010 oversize piston assembly for the LEV120's 40007 is the true updated # for .010 rings only. No idea why the parts listings are listed that way if it was intentional or a mistake (they do use the same rings). A .010 over piston assembly for the HS/LH is the 40005a.

As stated previously by me Tecumseh lit shows that they going to the elliptical pistons with T coating rather than the usual chroming in 2005 on the small frames based of the LEV120 piston design to reduce blow by and decrease friction etc... Based off though, not just using those pistons. Which is why I was curious of Skipp's findings an comparisons to an actual HSSK/LH piston.
note that my ID tag is dated 2006 making that list of 2005 and newer engines that has that coating process done. i'm sure the coating process was a lot cheaper then that chroming. well that didn't last long...tecumseh was done soon after.
 
#86
I'm a tech in a GM dealer. From what I've seen, the skirt coating ain't worth a darn. Every piston that I've removed it was worn to the metal. I'm not talking high mile worn out chit. Some only have 15,000 miles and coating is gone.
 

delray

Well-Known Member
#88
now if a guy could find the 20 over stuff...lol
View attachment 277070
I'm a tech in a GM dealer. From what I've seen, the skirt coating ain't worth a darn. Every piston that I've removed it was worn to the metal. I'm not talking high mile worn out chit. Some only have 15,000 miles and coating is gone.
Yes i agree,long term no good. More of a safety coating and after that...gone.
 

cfh

Well-Known Member
#89
if you need to bore .020 over on a smaller bore hs50/hssk50, and can't find a piston, there is another route you can take... use standard bore thick ring piston/rings... it's about the same as a .020 thin ring piston.
 
Last edited:

cfh

Well-Known Member
#91
My LH195 aka HSSK50 is mounted and did a test drive this week. It kicks butt. i don't have a tach installed, but would say in the 5000 to 6000 rpm range. really makes the Speedway Scorpion move. As a re-cap, it's a snowblower motor i bought for $25. Great bore, original hatch marks still visible. New oversized rings that i grind gap to .010", with a light/quick hone on the bore. 22mm slide carb and open exhaust. The cam is a Precision 30/30 cam, which is basically a Dynocam 245 clone. Bushing side cover.

http://www.pinrepair.com/minibikes/p/speedway1972scorpion_mine1.jpg
http://www.pinrepair.com/minibikes/p/speedway1972scorpion_mine2.jpg
 

delray

Well-Known Member
#93
working on cc my clone stuff so i thought i would see how much compression i have with this flathead. not impressive...lol
with my .032 copper gasket and stock head that has not been milled yet. i got a ball park of only 8.2+ only putting it just a tad bit higher then stock compression.
. 82s.jpg

base only on what i have found in my research on compression ratio for small block tecumseh flatheads. as of this point only info that i have found out there and this is for a 4hp engine. not a small bore hs-50 . i am assuming at this point the compression is the same?
tecumseh hs40 specs.PNG
 

delray

Well-Known Member
#95
8.0 is better than the flathead ford V8, 5.5 to 7.0 stock
i got couple ideals to bring it up little more. we have a 88 octane ethanol-free gas. i feel this works better then the 91.
my opinion 88 burns more efficient then the 91 with the compression so low.
my K series flathead 12hp in my 212 john deere runs good also with it.
scrappybunch can you get anything good for gas out east?
 
#96
i got couple ideals to bring it up little more. we have a 88 octane ethanol-free gas. i feel this works better then the 91.
my opinion 88 burns more efficient then the 91 with the compression so low.
my K series flathead 12hp in my 212 john deere runs good also with it.
scrappybunch can you get anything good for gas out east?
All we have around here is 10% ethanol. Av gas at the airport nearby, but have not been there in years. Raceway park in Englishtown used to sell race gas. They pretty much closed the track, except for a beer fest and a now lame swap meet.

I often wonder if this new style head offers any performance gains.
 

Attachments

#99
Saw one in Kimball Ne, that's just a mile North off I-80 that i use. Card pump only. Need to update the coordinates tho.

Not sure think there's another one here in Antelopeville that peddles 85 octane ethanol free. I'll find out and update it.
 

delray

Well-Known Member
Saw one in Kimball Ne, that's just a mile North off I-80 that i use. Card pump only. Need to update the coordinates tho.

Not sure think there's another one here in Antelopeville that peddles 85 octane ethanol free. I'll find out and update it.
85 octane would be good for some low compression flathead motors.
 
Top