Forums Archive Index > Outdoor Power Equipment > Tecumseh Carb/Governer adjustments.

Author: BigRigTech

Date: 14 Dec 2005 5:49 pm

I have an 88 Craftsman8HP/25" machine. The thing ran like crap this morning but it got my driveway cleaned out. It was flooding really bad so I got a new needle, float and bowl gasket today installed it. I also fixed the messed up governer/throttle linkage by looking at a pic from the manual. The old float had a hole in it and the bowl gasket was toast. It started and runs much better but I have 3 little nagging issues.

1. I can't idle it with the recommended 1.5 turns from seat, it idles great at 3 turns out.

2. The high speed/main mixture screw is almost seated in order for the the machine run at high speed without "surging or hunting". Due (in my opinion) to the lean high rpm mixture the muffler is glowing so it's gotta be running way too lean....Glowing like a exhaust header after a lean pass down the 1/4 mile. :roll:

3. When I push the throttle to FAST, it's gotta be running more than 3600rpm and it seems to be coughing a little through the carb as it runs. I bumpd the throttle down a little and it works ok and sounds closer to 3600rpm. I need to set the high speed rpm I guess.

I need to grab a 11/64 drill bit from work tommorow (couldn't find one in my mess of a shed :roll: ) to set the float level and I have 2 mulitmeter's with built in tachometer's here so I'm going to set the idle and high speed rpm tommorow night. On the plus side it does throw snow harder and further than it was before and I haven't painted/waxed the bucket or shute either. :D ...That's a Job for Sunday morning. :wink: It's not leaking gas from the carb anymore so that's a bonus. Any input on the above issues anyone? I'm so close to perfection I can taste it...LOL...It's no Brigg's but I guess I can make it work almost as good...LOL :D

Author: HONEST TECHNICAN
Subject: Carb problems

Date: 14 Dec 2005 6:56 pm

Hi there bigrich 1. start by checking all controls that they are in the right order, by looking @ pictures in the book are not always correct, hopefully you replace them in the same order. 2. Start and warm up machine and screw idle needle valve in see if it stops the engine, if it doesnt then a idle passage is plug with dirty fuel. You might have to make adjustments @ the throttle lever screw... see if this works. 3. You said that the main needle is scew in close and running lean, trying setting it @ 1.5 turns out and see what happens from there. You should be able to richin or lean it with about 1/8 - 1/4 turns either way , if you can lean out the main screw with no change at all there a problem with the screw or main jet. 4 You purchase new parts are they the right parts, 632019 float is correct butafter you preset the float see what happens... chat back and fill me in if more info is needed.... Welcome to the forum jim

Author: BigRigTech

Date: 14 Dec 2005 7:36 pm

Adjusting the idle screw in towards the seat makes the engine stumble and want to die, I tried to set it to 1.5 turns from seat and it wouldn't run...I backed it out until I heard the engine smooth and pick up a little rpm at idle. I'll try it again tommorow with the tach hooked to it.

As for the controls, they look right now. The way they were when I bought it wouldn't allow the governor to "work" as you pushed the machine into the snow. Everything moves freely now and the high speed rpm adjuster screw on the throttle lever is useable now. The first pic is how it was and the 2nd is how it is hooked up now. I checked my float number, it matches what you said.




The main needle will work at 1.5 turns from seat but it's surging, the more I screw it in the more it smooths out and the rpm peaks. When I get it to run smooth the muffler is glowing.

On a side not, my little Brigg's 5HP genset does this too but it runs great, I tried to richen it a little but it doesn't run quite as good. It has a carb mounted fuel tank.

Author: HONEST TECHNICAN
Subject: CARB

Date: 14 Dec 2005 8:41 pm

Hi there im not sure by looking @ the picture but the throttle control plate looks like it upside down down... the leakage of the bracket always goes up. but like I side im might be looking @ it wrong.. what needles did you change... let me know ---jim

Author: HONEST TECHNICAN
Subject: control bracket

Date: 14 Dec 2005 8:47 pm

The more I look @ the control bracket the bracket that holds the governor rods on should go up yous looks down that could explain why its running over 3600 rpm. If this is true the carb is trying to compensate for air/fuel mixture would be off.... double check the control bracket --chat tomorow.. jim

Author: BigRigTech

Date: 15 Dec 2005 4:03 am

The picture is how it WAS before I changed it, the drawing from the manual shows how I have it now. My linkage is pointing up like in the drawing from the manual. The throttle lever actually matches the carb cover, down is slow and up is fast. I haven't changed any of the needles, they looked ok when I cleaned them. :wink: [/b]

Author: BigRigTech
Subject: brain fart.

Date: 15 Dec 2005 6:26 pm

Well all was going well tonight, I set the carb up and it works great now, I installed a kill switch on the engine as the old one was gone. I took it outside to try it, pushed the throttle to fast and pulled the cord, it took off like a shot, let out a couple of knocking sounds and shutdown. I tore the flywheel off and found it had sheared off the key between the crank and flywheel...Never seen that before...LOL...Must be a Tecumseh thing. :D
So tell me this, besides the "1/2 moon key", did I do any other damage? I'll get a new key tommorow. I know I put the flywheel nut on plenty tight but maybe the flywheel wasn't seated all the way on? :? Oh well, live and learn. I can't push the throttle all the way to FAST as it overspeeds, I won't forget that next time. :wink: I was all set to push the Craftsman outside and wheel in the Gilson to get that one going too...Duoh!

Author: snowshoveler

Date: 15 Dec 2005 7:38 pm

your not gonna want to read this...but.
the flywheel key on a tecumseh seldom sheers for no reason.
they do however sheer when the connecting rod breaks.


please tell me your engine still has some compression.
if it dosent then look behind the electric starter,there should be a crack or even a large hole.
i dont like to be the bearer of bad news ...but i might be this time.
let me know whats wrong with it.
chris
ps ...i see a road trip coming up :wink:

Author: HONEST TECHNICAN

Date: 15 Dec 2005 7:54 pm

hi there big rich....snowshovler is correct check that out first. next flywheel key does shear unless the flywheel nut was not properly torgue to spec, or a belt or something is dragging.. i said a prayer and hopeing for the best..... :)

Author: BigRigTech

Date: 15 Dec 2005 7:56 pm

Well, there aren't any oil puddles or holes that I saw...LOL... it still cranks over pretty easy by hand - no electric starter on either machine. I wonder if I didn't have the flywheel on tight enough? When I pulled the flywheel cover I could turn the little "cup" that goes between the crank nut and the flywheel by hand and the flywheel nut was not as near as tight as I had put it on. Almost no effort to loosen it. :shock: I'll take a run out and look for holes....LOL

Author: HONEST TECHNICAN

Date: 15 Dec 2005 8:00 pm

If that the case the flywheel nut was not properly torgue, the nut and cup should not move @ all. I WILL double check but I think its 40 -50 ft lbs.......whatS the model again ....

Author: snowshoveler

Date: 15 Dec 2005 8:06 pm

when the key sheers the nut and cup usually come loose.but not always.
if you are lucky you will just need a key and proper torque.
chris

Author: BigRigTech

Date: 15 Dec 2005 8:16 pm

Ok, no oil puddles and no holes in the block...LOL...I pulled the spark plug - no damage and I can see the piston is moving in time with the crank. :D I did notice that if I rock the crank back and forth I hear a ticking sound - my guess would be a large bearing clearance on the rod bearing, what do the Tecumseh's usually run for a clearance? Don't get the wrong impression guys, I build SBF engines all the time and I fix small engines as a hobby for family and neighbours. This is the 1st time anything like this has happened to me. :roll: I'm currently building a 351W (357cid) for my drag car project and it's going to be twin turbocharged. :twisted: I had to frig with a 11.5HP honda this morning at work to get it going, funny how they won't run with 3 loose clamps on the fuel lines...LOL

Author: snowshoveler

Date: 15 Dec 2005 8:24 pm

okay bolt the thing back together and get er done will ya the suspense is killing me.
just kidding.
the torque spec will be posted tomorow (unless it comes in before )
just remember that the flywheel key is a locater not a driver.
it just lines up the magnets for your iginition timing.
the taper on the crank and flywheel is the actual driver.
chris

Author: BigRigTech

Date: 15 Dec 2005 8:35 pm

I have a CD manual here for 3-11HP L-head engines so I'll look in there for the torque spec. I think it was like 45-50ftlbs if I remember correctly. How much rod bearing clearance do these things run? I think it took off like a rocket on me when I started it and that didn't help the loose flywheel issue...LOL...I never thought to check the main drive pulley bearing either....Maybe it went T.U.....It does roll over just as easy as before though.

Author: snowshoveler

Date: 15 Dec 2005 8:59 pm

crankpin dia 1.1860min
1.1865max

rod dia 1.1880min
1.1885max

so that would be .0025max

flywheel retaining nut torque 50 to 55 ft. lbs

chris

Author: BigRigTech

Date: 15 Dec 2005 9:00 pm

I guess we'll know if it's hurt at about 4pm tommorow....LOL...If it does go BANG I'll be sure to make it a big one...LOL :twisted:

Author: snowshoveler

Date: 15 Dec 2005 9:10 pm

are you planning on a tear down to check the rod.
not positive but i beleive the rod is about 40 bucks and the gasket is 5 or 6.
if it is indeed sloppy on the rod then most likley all you will need to do is polish the crank a bit and put in a new rod.
its not the excessive clearance that will do it in its the aluminum smear that has transfered from the rod to the crank
if you wanted to go high teck then you would have the rod machined to accept babbet inserts...lasts forever then.
chris

Author: BigRigTech

Date: 16 Dec 2005 4:09 am

So this thing has an aluminum rod?....Yikes....I wasn't planning to tear it down that far..."Run it till she blows" and then toss it for a Brigg's....It's hard to tell if the play is in the rod clearnce as I still have the belt on the pulley and the sound could be coming from underneath. Got any used 10-15HP briggs engines down there on the South Shore? :D I know that Briggs can be hard to start in the winter but once they fire they run great, I don't find them as fussy as these Tecumseh's....Just my opinion so far. :wink:

Author: BigRigTech

Date: 16 Dec 2005 4:22 pm

Wel, it's still alive...LOL....I put a new crank key in, torqued the flywheel to 50Ftlbs and fired it up. It's running good and other than trying to stop the throttle lever from causing overspeed I'm not touching it anymore...LOL :roll:

I gotta take the broken crank key on the chin, my "hand feel" tighteness was no where near the 50ftlbs I set it at with my S&K torque wrench today...My bad. :oops: NOw I gotta torque the flywheel on the big machine too. :roll: Got any suggestions for the throttle? Look at the pic's above to see what I mean. If I move the throttle lever all the way to the top it's in "fast" and it is way above 3600rpm, I can tell that by ear...So much so that it cough's back through the carb. I tried my tach on it last night but I couldn't get a consistant reading. I forgot to bring home my good multimeter from work.

Author: HONEST TECHNICAN

Date: 17 Dec 2005 1:16 pm

hey there, try running the engine while you hold the governor lever is it controlable or does it still run wide open.. ill check back....jim :o 8)

Author: BigRigTech

Date: 17 Dec 2005 1:38 pm

Ok, I'll try that. I just spent the morning working on the Old Gilson 10/26 machine, I got it running like a champ. :D Now I have to free up the auger and pulleys to see it throw some snow. That 30 year old Tecumseh works better than the 88 Craftsman does. :wink:

Author: bbwb

Date: 17 Dec 2005 4:08 pm

Tucked behind the throttle lever is a high speed rpm screw. It takes a little bit of looking but you should be able to find it. Just turn the screw to lower the top end. :)
bbwb

Author: BigRigTech

Date: 17 Dec 2005 4:37 pm

Tried that all ready, doesn't do squat. The problem is in the lever, it travels too far and goes to WOT. I need to make a stop for it I guess. This carb is all or nothing, it's extremely sensitve. The governor seems to be free, no binding that I can see. I'm probably gonna ditch the lever setup and go with a cable. The cable setup on my old Gilson works great and it doesn't overspeed.

Author: BigRigTech

Date: 17 Dec 2005 7:57 pm

Here's another issue on the 8HP engine, if I set it up to run good at higher rpm's it won't idle or vice versa, if it idles good it surges at high rpm's? The throttle shaft is loose in the carb so it's probably sucking some air through that which isn't helping. I replaced the float, needle and bowl gasket after I cleaned the carb thoroughly. I have another carb here in much better condition, I just need to check the numbers and see if it will fit the application.