tecumseh hs50-67244e has me stumped

[38racing]

it's on an ariens snowblower with some history. dumpster dropoff few years back missing wheels. I cobbled some wheels.Memory not complete as it has what looks aftermarket carb that I may have installed. I remember that it started fine and ran except engine would die when it started to blow snow. Back then a forum suggested it was lack of clearance on exhaust valve. Indeed it was and when I ground to create clearance it ran and blew snow. But it's been sitting idle again, in shelter last winter. I decided to pull out this winter but cobbled wheel broke. got some better used wheels but when checking it over I noticed wheel drive belt riding on edge of large pulley instead of in groove. I found top and bottom pulleys out of line. To remedy this I removed bucket and moved big pulley forward and small pulley (on cam shaft) slightly inward toward engine. When I started the engine after this (started and ran fine) there was a clunking noise in the pulley area. When I engaged the wheel drive the noise disappeared. I repeated just a brief period and shut it down. I removed bucket and it was obvious that the mounting stud ends of the wheel drive pulley were now hitting those of the auger pulley. Since engaging wheel drive moves its pulley away from auger pulley the noise would stop. I proceeded to move pulley back a bit and cut off the mounting studs of both pulleys flush with the nuts. I replaced bucket. Now the engine won't start. It has electric start so rpm is good. (no pulley clunking when it cranks) At times it had a week fire from muffler but only as it stopped when I disengaged the starter. I checked spark. Jumps the 1/4 gap of that black tester. Has fuel. primes plus I try with carb cleaner. Compression 150 psi. Leakdown at 25 psi about 20% and leaks slightly at both intake and exhaust. So i get to thinking spark timing or valve timing. Verified flywheel key. Removing plug I see both valves moving and appear in time with piston. Also checked valve clearance. spec 8-12 thou. intake at 12, exhaust at 16 (bit surprised at that but maybe I over ground the stem way back). Then I think if wheel pulley, being driven by cam shaft, could have shifted crank gear driving cam. engine on bench now. I remove side cover. Crank gear is press fit so in theory it could shift. I set cam timing off by a tooth but in hind sight I think I went the wrong direction. No change. I did remove head to verify valves and seats. Timing 'seems' close as I get the valve overlap at tdc exhaust. While head is off I sprayed carb cleaner on valves and sent compressed air into intake. some leakage. I lapped the intake but I still get some leakage on that air test. So then I wonder if this is the old coil issue, good spark in testing, but not under compression. Anyway I have crank and cam timed back to marks on the gears, a different coil that again jumps the 1/4 " gap, the 3rd sparkplug (new ngk) , compression still 150 psi and it still just cranks with no fire, no backfire, just like there was no spark but the inline tester is sparking. There is air? fuel mixture? exiting muffler. Maybe I should hold a bbq lighter there? I'm baffled. I've reviewed my go karting stuff from 25 years ago and thinking of checking the centre lines of the cam to verify timing. I assume I could do same on another tecumseh engine for comparison. Wondering if cams are normally installed straight up in these engines. Any suggestions much appreciated. My wife's suggestion is that I have more important things to work on.

[creia]

Is your compression tester/gauge reliable? 150 PSI on a Tecumseh HS-50 seems REALLY high....
Michael

[bgsengine]

Is your compression tester/gauge reliable? 150 PSI on a Tecumseh HS-50 seems REALLY high....
Michael

Agree.. Something ain't telling you the truth on your testers.... I'd also be checking that gas (pour a small capful, take it outside and see if a match will ignite it easily, maybe? OTOH if you are actually seeing 150 PSI I might suspect that your ignition system is not capable of firing under that much compression (I think you would need something like 25Kv to fire a plug gap of .025 in that environment) So if it is actually 150 PSI I might wonder if the head has been shaved, or something altering the compression ratio.

[38racing]

Is your compression tester/gauge reliable? 150 PSI on a Tecumseh HS-50 seems REALLY high....
Michael

Agree.. Something ain't telling you the truth on your testers.... I'd also be checking that gas (pour a small capful, take it outside and see if a match will ignite it easily, maybe? OTOH if you are actually seeing 150 PSI I might suspect that your ignition system is not capable of firing under that much compression (I think you would need something like 25Kv to fire a plug gap of .025 in that environment) So if it is actually 150 PSI I might wonder if the head has been shaved, or something altering the compression ratio.

I'm pretty sure about the compression gauge but I can try another. Actually put some gas from tank into a bottle to check for water. Current gas is in other running engines plus it won't fire on sprayed in carb cleaner. I'm now wondering if there is compression release ground into the exhaust lobe (no external device). The .016 clearance might cause it to fail. I do find the pull chord is a hard turnover, again like too much compression. My supplier has a standard exhaust valve available so I'll order one. Maybe I'll drop the plug gap to .020 and see if it pops at all. Be funny is it's the exhaust valve and it just reached the point of failure after I did the pulley wirk.

[KE4AVB]

Since the image of the 33696 camshaft shows no mechanical compression release it probably has either a BCR or RCR grind on the exhaust lobe per the service manual here.

BCR = Bump Compression Release
RCR = Ramp Compression Release

Valve clearances are .004 In and .010 Ex

[38racing]

Since the image of the 33696 camshaft shows no mechanical compression release it probably has either a BCR or RCR grind on the exhaust lobe per the service manual here.

BCR = Bump Compression Release
RCR = Ramp Compression Release

Valve clearances are .004 In and .010 Ex

where do get the valve clearances? I thought I saw 8-12 but also just re-checking the tecumseh 3-11 hp manual the h50 had the 8-12 but the hs50 prior to G (I missed that earlier) is .004-.008 . So I'm way off. Unfortunately the intake valve is pricey where I see it. My supplier doesn't have it, I may check ipl of various tec mower engines I have and see if same valve number pops up.

[KE4AVB]

Service manual is dated 1998 so you may have different manual than I do.

[KE4AVB]

What I finding valve wise is Intake 32644A is around $8 but it is the Exhaust 29313C that is the problem. It is NLA from Tecumseh. Now Rotary still has some of their 1518 valve but they are discontinue when stock is depleted.

[38racing]

What I finding valve wise is Intake 32644A is around $8 but it is the Exhaust 29313C that is the problem. It is NLA from Tecumseh. Now Rotary still has some of their 1518 valve but they are discontinue when stock is depleted.

my supplier has the exhaust but best I can find for that intake would cost me $30 cdn to get delivered to me.

[creia]

The first thing I would do (before spending any $$) is set your valve lash properly (.004-.008") then try starting it again. When old "T-Man" was on this forum (I miss him ) he said set them both to .006", which I have been doing for years. I bet when you do that you will find that it is easier to pull the starter cord by hand then it was before, and.... it just MIGHT even run!
Michael