Hi mow master! Welcome to the group. Wow, I get pretty excited every time I see that somebody else has a vintage Jacobsen.
I looked up your model number on that site Austen listed. Scroll down the list on it to "4-Blade Rotary 18" and you'll find your model number, 31807 in a second list. Then enter serial number 9416 and you'll find that it was manufactured in 1964.
Tell us more about your old Jake, and maybe post a picture of it. Does it have a steel or cast deck?
Parts lists and owner's manuals show up every now and again on ebay. I've also had great luck in contacting Jacobsen/Textron. They have some manuals for the vintage mowers in their archives, and have shared some for machines I have. You just need to provide them with the model and serial number with a description of what you're looking for,
Thank you for taking the time to provide information sincerely.When I got the lawnmower the connecting rod and cap was shattered.I found no needle bearings in the crankcase, so I wondering if used something like main bearing inserts instead of needle bearings. I am block walled for now. Again thank you
I'd give jacobsen/Textron a shout and see if they cound't get you a parts list with exploded diagram. I'm not an expert on Jakes by any means, but I would venture a guess that your mower has one of their tried and true 321 engines.
Sourcing new bearings shouldn't be a problem. Places such as Napa who can cross reference part #'s still carry a supply of these types of bearings.
Like Bruce mentioned, see if they can supply you with any parts numbers. I can give you the part numbers for the crankshaft bearings (roller and ball) from the parts list that relates to my Lawn Queen as there is a pretty good chance they would be the same ones used in yours, but I would first check to see if Jacobsen can supply you with the exact #'s to start out with.
Jacobsen/Textron was kind enough to send along a 6 page pdf with exploded diagrams and parts break down of your Jacobsen. The file exceeds the size I'm able to attach, so send me a PM and I'll send it to you via email.
The parts list shows the connecting rod part number to be 153255, and rings to be 500794.
There happens to be a connecting rod and rings on ebay right now, although the part number they have to the rings is 500795, but the rod is the same. JACOBSEN "NOS" 2-STROKE RINGS & CONNECTING ROD | eBay
A member of another forum was kind enough to send me a set of Jacobsen blades he had from old stock that he thought would fit my 18" mower. Unfortunately, they do not, mine are a different part number, but the part number on this package matches the part number listed for your mower. #106326 If you'd be interested in them, I'd be happy to send them to you for the cost of shipping. Just let me know.