Valve Clearance Problems Help

[KartBuilder88]

iv got a Tecumshe hm80 156534s 8hp engine iv been rebuilding, the valve clearance is wider than it should be, and im wondering should I replace just the valves or the lifters as well? any suggestions or advice would be great, the intake should be .008 and my feeler gauges only go up to .032 and its more than that so its wayyy off I was even able to slide the .020 and the .021 in together so that be like .041 right? so its deff wayyy off and im hopeing a new valve and lifter or just a valve would fix it and its not a worn cam lobe, idk . the exhaust should be .012 and is .020 so not as bad on that side but would still like to and probably should get a new valve for it and im thinking just a valve on that side will fix it, idk , like I said any suggestions help or if you've dealt with something like this would love your help thanks

 

[ML-TOYS]

You really dont have to make 2 identicle posts regarding this. Someone that knows will answer.
Not everyone reads every post made all day lond as soon as its made so be patient

 

[OzFab]

Umm, yeah, that's a massive gap

The lifter on the left appears to be much shorter than its partner; if you know a good machinist, you could have it extended but, since you'd need to remove it anyway, it's probably cheaper to simply replace it...

Sorry I can't offer any further advice...

 

[KartBuilder88]

the lifters are only like $7 each and the valves are also pretty cheap, im just wondering could it be the cam lobes themselves worn or will it be enough to replace the valves and lifters, the gap is just huge could the valves and lifters be that worn and not the cam? the lobes didn't appear to have wear but neither did the lifters or valves until I checked the clearance

 

[Poboy kartman]

Welcome to the forum.....I doubt replacing a valve would do anything...tappets yes.....are both those tappets the same length? ??

Did you put them back in the same holes????

I'm thinking if you switch them...you may get an equal gap...or close to it....with the exhaust being slightly wider.....

I'm thinking you need a new cam and tappets....

Posting up pics of those parts out of the engine might help....IDK.....

 

[OzFab]

You really dont have to make 2 identicle posts regarding this. Someone that knows will answer.
Not everyone reads every post made all day lond as soon as its made so be patient

Threads merged...

the lifters are only like $7 each and the valves are also pretty cheap, im just wondering could it be the cam lobes themselves worn or will it be enough to replace the valves and lifters, the gap is just huge could the valves and lifters be that worn and not the cam? the lobes didn't appear to have wear but neither did the lifters or valves until I checked the clearance

It's likely but, impossible to tell without measuring the lobes; it's more likely the bottom of the lifters are worn than the cam lobes...

 

[KartBuilder88]

yes the tappets or lifters are the same size and part number, I defiantly put them back into the same hole, but ill try switching them and see what happens because im planning on getting now ones anyway so it couldn't hurt, idk just hopeing its not the cam

 

[KartBuilder88]

I take pics of every step I do on workin on my karts so ill post a bunch when I get off work, thanks for the help everyone

 

[landuse]

I take pics of every step I do on workin on my karts so ill post a bunch when I get off work, thanks for the help everyone

Taking pics of every step also helps in putting stuff back together the right way

 

[KartBuilder88]

ya I take pictures and label everything, anything worth doing is worth doing right .... Dr. Hunter S Thompson

 

[KartFab]

*ignorantly wonders* do they have longer lifters and valves?

 

[KartBuilder88]

they might but not on the parts list or not that iv seen when looking online, iv seen the oversized piston rings and valves but not lifters, and the over sized valves are the stem size and not length, there for when the valve guide gets worn and you have to bore it out 1/32 over sized then you get the ones with the larger stem but the length is still the same, but good thought, im guessing im just gonna have to buys new valves and lifters and see where that lands me and if that's doesn't fix it the only other thing it could be is the cam, but a new cam is double what I paid for the whole motor, but at this point im not stopping ill do what it takes to get it running iv already gotten new intake pipe, air filter assembly, carb, gasket kit, breather filter, gas tank, had a machine shop hone the cylinder ($35 if anyone was wondering), so at this point its gonna run d@M*t, lol, I got the whole kart and motor for $50 (craigslist) and I didn't want to just junk the motor, soo idk thanks for the help all and ill keep this updated with what ever solution I come to

 

[Poboy kartman]

they might but not on the parts list or not that iv seen when looking online, iv seen the oversized piston rings and valves but not lifters, and the over sized valves are the stem size and not length, there for when the valve guide gets worn and you have to bore it out 1/32 over sized then you get the ones with the larger stem but the length is still the same, but good thought, im guessing im just gonna have to buys new valves and lifters and see where that lands me and if that's doesn't fix it the only other thing it could be is the cam, but a new cam is double what I paid for the whole motor, but at this point im not stopping ill do what it takes to get it running iv already gotten new intake pipe, air filter assembly, carb, gasket kit, breather filter, gas tank, had a machine shop hone the cylinder ($35 if anyone was wondering), so at this point its gonna run d@M*t, lol, I got the whole kart and motor for $50 (craigslist) and I didn't want to just junk the motor, soo idk thanks for the help all and ill keep this updated with what ever solution I come to

Too bad Poboy was already taken.....

 

[OzFab]

Hey, do me a favour (which may help the diagnosis), grab the end of the lifters with needle nose pliers & see if you can lift them to meet the valve stems; if you can lift them, that would indicate worn lifters...

 

[porsche930dude]

does youre engine have a centrifical compression release on the cam? maybe something is wrong with it. But I woudnt worry about it at all. I actually make the clearance on most of my engines way bigger than theyre suposed to be. It gives them alot more compression and power because the valves stay closed longer. but thats on smaller briggs mostly without a comp release. I think youre engine has a compression release on the cam and that could be making things funky for you

 

[KartBuilder88]

yes I can lift the lifters to meet the valve stem, iv got the crank case cover off so I just stuck my finger in and lifted the lifter instead of using pliers but same effect ,has compression release mechanism on it and my thinking is that the valves arnt going to open as much as the should and not suck or push out as much air as they should, and since the biggest gap is on the intake side its not going to suck in as much air as it possibly can resulting in power loss , im not worried about the compression they close all the way and have been lapped, im goin to go switch the two lifters around and see what happens to the gap maybe its possible I didn't put them back in the right one but most likely goin to just have to order new ones there probably worn, I wish I could find the specs of how long they should be and just use a caliber to measure them but cant find the specs, idk well see

 

[KartBuilder88]

ooook problem solved
I was checking valve clearance with the crank case cover off which was making the camshaft sag, once I aligned the camshaft and put the cover on everything was right, no need for valves lifters all good... my bad lol , so don't check valve clearance with the crank case cover off was the lesson of the day

 

[OzFab]

OH, COME ON! You never even mentioned that the side cover was off until post #16; if we'd known that in post #1, the problem would've been solved in post #2 :toetap05:

 

[landuse]

OH, COME ON! You never even mentioned that the side cover was off until post #16; if we'd known that in post #1, the problem would've been solved in post #2 :toetap05:

He he

 

[zbuck]

ooook problem solved
I was checking valve clearance with the crank case cover off which was making the camshaft sag, once I aligned the camshaft and put the cover on everything was right, no need for valves lifters all good... my bad lol , so don't check valve clearance with the crank case cover off was the lesson of the day

You can check the valve lash with the sump cover off. They make a jig for B&S that replaces the sump cover so you can set up the cam and valve lash. For a Tecy. cut down and old sump cover. Cut it down so that the crank and cam bosses and dowel pins holes along with two bolt hole are all thats left. I did this years ago when we were racing B&$ and Tecy flaties.