Gravely Tractor L8

My Gravely Tractor L8 won't start, and the experts all say it is because of stuck valves, especially the exhaust valve. I pulled the head and turned the crank shaft numerous time, both valves were going up/down and looked like thy were seating properly. Put the head back on as one person said to place thumb over sparkplug hole and feel the compressed air. Tried that and there wasn't any air pressure? Well guess the head comes back off and remove the valves. The exhaust valve had some build up and was a bit sticky, so took the electric brush and cleaned it up. Cleaning the tub, found loose screws holding the manifold, the carburetor inlet screws were loose too! Thinking this maybe the no compression problem?
Any comments much appreciated as I would like very much to get these Gravely Tractors running like new again. Thank you.
Bob
 
if i read you you say the carb manifold bolts were loose;;that will not cause a no compression issue..i think you were looking at the culpret and that being the valves,,you neeedto check the valve stem and tappet clearance depending on what motor is in it the clearance will vary.
 

Farmerjohninpa, Yes after thinking about I realized that. Thank you for your suggestion about the tappets, they looked a bit worn in spots and would have thought that the guides would have better supported them? Plan on assembling the jug today and making all those adjustments. Wondering about the lubrication, didn't see any oil down it the bottom, though realize it has a forced system.
:roll:
 
My L8 builds up pretty good resistance on the compression stroke, so you should definitely feel it. Some other thoughts, head gasket or warped head, piece of carbon under valve holding it open. You might want to lap the valves before setting the valve lash. Good luck!
 
(quoted from post at 15:18:29 09/30/20) My L8 builds up pretty good resistance on the compression stroke, so you should definitely feel it. Some other thoughts, head gasket or warped head, piece of carbon under valve holding it open. You might want to lap the valves before setting the valve lash. Good luck!

Yes, Lapped the valves then, got into the bottom and yes you were right. You can't believe this, there wasn't any adjustment to be found in either tappets. Sure happy there wasn't any bent valve stems. It takes me so long to do anything as there is so many things along the way that needs fixing or a gasket needs to be made up. Magneto repaired, points reset, timing was a bit of a problem. Tomorrow repair the carburetor, that going to be fun. Head back on, held finger over hole compression is there, but think it should be better?
 
(quoted from post at 15:18:29 09/30/20) My L8 builds up pretty good resistance on the compression stroke, so you should definitely feel it. Some other thoughts, head gasket or warped head, piece of carbon under valve holding it open. You might want to lap the valves before setting the valve lash. Good luck!

Carburetor was a beast, took all day to clean and make a gasket. You can't believe what was found? The gasket that was in there wasn't fitting properly and the collar to the venture wouldn't go through the gasket to fit proper. After making and fitting a gasket, all back together checked it with a feeler gauge, the front took a .006 feeler. Found upper half forgot to clean surface of some stuck gasket material. Took a find file, and hone, good to go. Hopefully get it all together today and give it a try.
Thanks for your help Bill.
 

Farmerjohninpa, you were correct about the tappets. Just can't believe what is being found going through this 1968 Gravely L8 Convertible. It looks really nice, but with plenty of problems, and have 4 of them, done working. This one don't remember where it came from and have had it for about 15 years.
Thank you for your help.
 
Farmerjohninpa, Warped head? I hope not as surface plate and boring/milling machine just went miles away to a friend. Do have a bar that is used for a straight edge though and should be able to check it with some red lead? Can't believe as nice as it looked that it is off and if it is hopefully can hand scrape it in? Thank you for your suggestions, it gives me all the confidence having you experts helping me out.
 
:cry:
1967-1968 Gravely L8 Covertible back together except for the forward and reverse levers. Battery on and charger to that as well because can't seem to recharge battery. Fuel starter to carburetor, it wants to start for a second, but then nothing. Tried numerous times, oil in top of piston most came out. Had to sleep on it until now, couldn't remember if the shut-off valve at the tank was turned on so went and checked. No, forgot to turn gas on! :cry:
 
Okay, if it doesn't start the head is coming apart again. There was a number stamped on top of the piston .010 so guessing someone was in here before and had bored the tub .010 oversize? Checking bore and honing bore next, and ring gap spacing. Also isn't there a correct way of ring positioning like correct side up and proper positioning of gap from each other? Is there a proper way of honing
from top or bottom? Any comments much appreciated thanks. :?
 
Maybe old carbon stuck between valve seat
and valve ? And the throttle should be wide open
when doing compression check , maybe air inlet is
completely plugged up with nature’s bugs ?
 
Okay the latest on my Gravely L8 Convertible. Turn the gas line on at the tank, sprayed some starter fluid into carburetor, hit the starter switch and it started terrible loud and backfiring then stalled. Did it twice and realized that it will go if the backfiring problem can be adjusted. Don't know which way to make adjustment? Assuming it is advanced too much? any suggestions much appreciated thank you.
 
I would try and find out which magneto you have. There are two, Fairbanks Morse and Wico. Mine has a tag on the side and the name on the black cover. The impulse coupling should snap at top dead center on the compression stroke. You should get a bright blue spark. There are free manuals on the internet, also suggest you get them to help identify what you have. Hope this helps, Bill.
 
Bill,
Thank you. I went through the timing again and couldn't get it any better as it was perfect, the alignment lines all matched up. The Wico magneto cleaned, points realigned, filed, reset, bright blue flame from spark plug. Started it again and it roared like a lion and kicked like a mule, then stalled! The oil pressure gauge just inside the normal range. Tinkered with the carburetor to slow it down to a fast idle, enough to work the levers and they won't work? Still runs way to hot, thinking too much air, and it will stall at idle? Breaks my heart, at a loss, limbo, don't know what to do? Wanted this Gravely going as it is the newest, with the most HP. Snow will be coming in a couple of months so on to number two Gravely, and will have to come back to this one in-between? It's all good, we will get there, four Gravely's and sure one or two will be running soon?
 

If it's backfiring with the timing set right the mag marks are likely off. It happens over 65-70 years when people ahve them repaired and someone messes up. In the manuals someplace there are instructions on setting them up. Also, when you timed it you didn't roll it to TDC and then back off to 3/8" did you? There is likely lost motion there so always bring it in the proper direction to 3/8" before TDC and set it.
 
(quoted from post at 13:37:33 10/07/20)
If it's backfiring with the timing set right the mag marks are likely off. It happens over 65-70 years when people ahve them repaired and someone messes up. In the manuals someplace there are instructions on setting them up. Also, when you timed it you didn't roll it to TDC and then back off to 3/8" did you? There is likely lost motion there so always bring it in the proper direction to 3/8" before TDC and set it.

Thank you Bret4207,
I have noticed (2) settings for the electrical timing of the magneto, and TDC of the piston. The 3/8" and the 5/16" with the head on. You are so right as when someone get's into these Gravely's they leave a lot to be questionable? It takes me forever to go through repairing one, don't want mistakes and try to be methodical and meticulous. I not only want it to look nice, it has to run nice too. Some people say "Bob, you dub around too much!
Bret4207, it is all good and I am not complaining. Thanks again!
 
Bret4207,
Yes it is human to make mistakes, and I am far from perfect as this 1966 #2 Gravel L8, found the timing and TDC was out 180
degrees from one another. Hey, you know who was in there last? It was me! Took all day cleaning, setting points, and filing them
flat, cleaning electrical contacts, re-timing and so on. It was all fun in the sun. Went to start her and boom started right up,
but had to use the choke to keep it going, then it stalled. Took the spark plug out and it was a bit damp so let it rest a bit.
Went back about an hour and it wouldn't start, guess what forget to turn the gas on. LOL I am not the sharpest tack in the box!
 
Bret4207, Yes read more about set-up of the timing. Had it set so the line on the coupling lined up with the dot on the magneto which is correct. Read the manual instructions numerous times and the last time it dawn on me as the instructions said to be sure that the piston is starting on down stroke. TDC and clink from the magneto wasn't quite starting on the down motion of the piston so reset. will know for sure when it is all back together. Have it all apart again, measuring ring gaps, removing carbon build up in top of cylinder, going to re-lap valves. Don't like what was found in the ring gaps.
Bob
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top