Export thread

First time joining a forum great to be here ok heres my headache I have a 8 hp tecumseh motor on a craftsman snow blower wasnt running so I did a carb rebuilt which ive done many times to simalar engines everything went well now it starts runs great for 2 minutes thrn backfires I directed my attention to the head gasket and spark plug after that I found my valves intake and exoust are out ....the exoust clearence from stem to valve lifter is .011 and intake is .012 ive done some reserch and found that the intake should be at .008 is this correct ??? If so what would be the steps for closeing that small gap!? The exoust valve could be filed down to achive the correct clearence but im some what stumped on the steps to close the gap if thrres to much ! New lifter? Valve seat re drilled pleas3 help !!!!!!!!!

We need the model number off of your engine to find the correct specs, but I think you have other problems, maybe a loose valve seat or something else.

Approximately how old is the blower?

Grind your valve seats and valves down. this will give you less stem clearance. That gap shouldn't give you a running problem. That is only .004.

The model number is hmsk80 155558u

Correction exoust is at .010

I can't see a valve clearance problem here. Check the lifters and cam.

When I examine lifters and cam do I just make sure there operating properly not bent????... any thing else to look at ?

jmart88 said:

When I examine lifters and cam do I just make sure there operating properly not bent????... any thing else to look at ?

Click to expand...

First of all is this a flat or L head engine. I am guessing it is. The lifters and cam shaft can't bend but they can wear out. To check this make sure they are getting a full lift. I really don't know this number but I hope someone else can tell you or if you can get a service manual it will tell you. If it is a OHV engine it could have a bent push rod. Seeing jmart88 gave you the right valve clearance maybe he also has the valve lift???

Tecumseh Engine Intake and Exhaust Valve Clearances

Like I said, I think your problem lies elsewhere, acceptable range for your engine is between .008 and .012.



About how old is the engine? If you were to start it up right now, describe in detail what it is doing, and when it stops, what happens when you immediately try to restart?

The engine is aprox 14 years old it is not a ohv if I put the hlast thing it did before I started takeing off the head and valve cover was it would start fine run smooth for 30 secs then rev very high backfire a few times then die everything that point towards running lean ..... maybe I should check carb sgain if valves are correctly adjusted .... I will also say I put new spark plug in and fly wheel key seems stuck on shaft not bent or crscked but stuck .... thanks for the help so far this is great!

Take off the nut off the bottom of the carb, and let it dribble in a cup, look at the fuel for dirt, and watch and see if the dribbling slows or stops, you may have a real clogged fuel filter, or screen in the tank plugged. After it sits a bit, fuel will slowly fill the bowl a bit, enough to run a tad. Look at the nut that you took off the carb, and see if the little holes in it are plugged up.

Got the machine running after relizeing the valves were indeed in check went threw the motins of checking fuel system .....crimed fuel line ccarb barley getting fuel thanks everyone for your time and input !

jmart88 said:

Got the machine running after relizeing the valves were indeed in check went threw the motins of checking fuel system .....crimed fuel line ccarb barley getting fuel thanks everyone for your time and input !

Click to expand...

It kind of sounded like that....

jmart88 said:

The engine is aprox 14 years old it is not a ohv if I put the hlast thing it did before I started takeing off the head and valve cover was it would start fine run smooth for 30 secs then rev very high backfire a few times then die everything that point towards running lean ..... maybe I should check carb sgain if valves are correctly adjusted .... I will also say I put new spark plug in and fly wheel key seems stuck on shaft not bent or crscked but stuck .... thanks for the help so far this is great!

Click to expand...

go back to basics, good fuel, clear fuel cap vent, clear fuel line, carb inlet fitting clear, back to the carb... Whats the spark plug look like NOW.. Is it fouling out or lean looking...Aint the valve lash.. Gene Kap.