Craftsman Garden Tractor Mower Blades Timing

[Scooby074]

I have a mid 80's Craftsman 18HP garden tractor that im trying to resurrect from the dead. Its a model c459-60418. I can find next to nothing about it online.

It hasnt run in well over 5 years, probably closer to 8. Well after cleaning the carb and giving it a major tune up, i have the engine running like a top.

Problem is when i engage the mower deck. THe blades are hitting in the centre. Its a rear discharge deck. This deck has a timing belt that connects the 2 blade spindles.

Currently the blades are "timed" so that they pass thru the centre at essentially the same time. I was under the understanding that the blades had to pass in the centre like this in order to throw the grass out the rear? Is this correct? Or should the blades be perpendicular to each other at rest? (see diagram). I have one of the blade hubs off (it was really rusted on there, much work) and I need to know where it should be relative to the other blade so they dont hit and the deck remains in balance.

Also one spindle bearing appears to be going. Are these spindles rebuildable? Due to its age, i doubt parts will be available, I cant find them online at least.

[bontai_Joe]

Your blades need to be perpendicular to each other at rest (90 degrees apart) so the tips don't hit in the center. Sine you ran it with them hitting, please inspect them for damage and balance.

[Scooby074]

Thanks for the reply.

One of the blades is chipped so it will likely have to be replaced. THe blades are very dull so this is a good thing.

I did rotate the blades over by hand before engaging the motor. There was no contact, so i felt it was ok to engage the engine. I was wrong . Looks like there was no damage besides the chipped blade.

I got lucky because Sears has been no help at all... I just love getting hung up on by their call centre flunkies when i try to explain that the mower has a spindle, and im not after what the front tire is mounted on....I seriously wonder where they get these employees.

Im just about ready to give up on sears, between getting hung up on and the fact that ive been waiting over 2 weeks for a mower drag link that should have been here last tuesday Found out today it was back ordered.. would have been nice if they had of told me that when i ordered.

[Scooby074]

I tried the blades perpendicular today. I dont think its right. Theres some vibration left to right. Im going to try having them inline, but ensure they wont hit as they rotate.

Another issue has come up. As i was testing, mowing heavy grass, I noticed black smoke and the engine was lugging.

After returning to the shop, i pulled the plugs.These plugs were new when i started. Both were carboned up, but one was "hot" the other was only warm. I tried the warm plug outside of the engine and there was spark. I should mention that this engine only has a low speed mixture screw, so no high speed tuning is possible.

Under pressure in the cylinder i dont think im getting spark on one cylinder, but it works fine outside the engine??

I was thinking the coil was bad, but this engine only has one coil for both cylinders (as far as i know) so i think i can rule that out. Unless theres a intermittent short in the plug wire or something.

tomorrow if i get a chance, im going to do a comp check and check the valves. Ill try moving the plug to the other cylinder and see if the problem is related to a bad plug.

Any other ideas, or things i should try?

[shot_gun]

Your dead cylinder may be firing if it is warm. Check the compresion of that cylinder first. Did you remove the covers and inspect for mice nest in the engine? Check the needle and seat on the carb also. Check the valve lash(clearance) also. I'm sure it's a briggs horizotaly opposed twin. Some parts are not available from sears but they may be available from an out side supplier. We order all our sears parts through a outside supplier. Check your local Lawn and Garden dealer and ask them if they can get sears parts. You can look the parts up on Sears web site and just give them the part numbers.

[Scooby074]

Shot Gun: Yes its a briggs HO twin. 18Hp Cast iron, model 422707.

I havent looked for any mouse nests specifically , but i have the hood off and will have a look around the shroud and engine area.

Ive just gone thru the carb, previous to todays running. THe needle and seat appeared to be ok.

I forgot to mention that although the plugs were carbon fouled, neither of them was wet with gas. But the exhaust smells rich. ANd theres black smoke under load. Also you can hear "putt putt" sound out the exhaust, as if im getting a small, intermittent backfire or a cylinder coming and going.

Quickly moving the throttle from idle to full throttle results in a puff of black smoke and a bit of hesitation. This will smooth out after a second or 2.

THe governer is working OK. There is no hunting for engine speed under load.

The only adjustment on the carb is low speed mix. I have it set to 2 turns out.

Ill try a spark test when the engine is cold tomorrow, to see if the coil is only working when hot. Youd think that the whole coil would be defective and not just half?

The mower starts very easily. Even without using the choke.

[Scooby074]

I got a little more troubleshooting in today.

No mouse nests that i could find.

Ran compression check 120 PSI in both cylinders!!! not bad for a 23 year old machine.

Checked spark again, concentrating on the cylinder that had the warm (not hot) plug. Instead of a plug, i used my spark tester. Only getting fire 1/4 of the time. "hot" cylinder had spark all the time.

Inspected plug wires, both looked good.

Looks like i got a bad coil. Picked up a new coil, $93 +tax . I hope to install tomorrow. Will post results.

[Scooby074]

I started a new thread to deal with the engine performance issues im having, It can be found here : Craftsman / Briggs 18HP Running on 1 cylinder - TractorByNet.com