Do not concern yourself too much with trying to match the existing mounting bolt hole pattern of the frame to a replacement engine.
The critical dimensions of the PTO end of the crankshaft are where you need to match so your pulleys will mount up and remain on the same "plane" as the OEM engine.
In mounting a replacement engine, you might have to drill at least "some" new holes in the frame.
The main point to abide by is that you keep the center line of the crankshaft in the exact point on the frame as it was on the OEM engine.
Usually the center line of the crankshaft is exactly concentric with the large opening in the frame where the engine mounts.
I have addressed the task of situating a replacement engine (with a different mtg hole pattern) by fabricating a plywood "template" to transfer the bolt pattern from the engine to the frame.
1. This method requires that round "centering disc" of 3/4" plywood be cut that fits tightly into the large hole in the frame of the mower.
2. Next, you locate the precise center of this disc and bore a hole that is the same inside diameter as the outside diameter of the crankshaft (measure the crank at the engine mounting area).
3. Next cut a piece of 3/4" plywood that is maybe a couple of inches broader than the mounting bolt hole pattern of the replacement engine and bore the same size hole in the center as you did for the centering disc.
4. Now you need a bucket or a concrete block (or other object) to lay this board on so that the engine can be lowered onto the board for marking the bolt hole pattern. The bucket or block provides depth for the crankshaft PTO end not to touch and thus allow the engine mounting flange to make full contact with the board.
5. Align the edges of the board to the engine so they are parallel with one side of the mounting flange.
6. Mark this side of the board now so you can lay it on the frame later in the exact orientation it is at this stage of fabrication (mark the engine too so you can match up to the board again).
Carefully mark the bolt holes positions onto the plywood by inserting a pencil down through the mounting holes. Be sure not to let the engine shift on the board as you mark each hole. If the engine has "optional extra mounting holes", mark them too.
7. After the hole positions have been marked on the board, remove the engine and drill holes in the board that are the same diameter as the holes in the engine mounting flange.
8. After drilling these holes, place the engine back on the board using the same technique as when marking and align the engine to the board according to the side marks you made.
9. Install 4 mounting bolts through the mounting holes to secure the board to the engine. This step is to assure the holes are a good fitting pattern.
10. If the holes are a good fit, lay the engine on its side and slide the round disc of plywood onto the crankshaft until it is against plywood board.
Secure the disc to the board with a couple of screws. After securing the disc to the board, remove the assembled template from the engine.
11. Now you have a bolt hole pattern template to transfer the engine pattern to the frame.
Place the template on the mower frame so it is oriented exactly like the engine needs to mount.
Check to see IF any of the OEM bolts holes match up with the holes in your template. If you are fortunate enough to have some existing holes already in alignment with the template holes, insert some bolts into these holes and secure the board to the chassis just tight enough that the board can't move.
12. With the board stabilized, drill the remaining holes "one at a time" and secure with bolts as you go until all the remaining holes are drill in the frame.
Good luck and be careful.

Hi Mownie,

Thank you for your detailed solution to replace my engine! If I was quite a bit more skilled I would give it a try.

Thanks again,

Ralph

Maybe these guys can tell if another brand engine will bolt up?

http://www.tulsaenginewarehouse.com/

You might go ask yer friendly mower repair guy if he might have an old sump from a Briggs engine, that you could use to see if yer bolt holes in the frame will fit. just mark the sump as to the way the spark plug points (ie), to the front or side or back of the engine, before you take the sump home.
I would think the holes are the same in your frame, because the mfgrs would use different makes of engines, some times.

Hi Rustyj14,

I like your idea about matching the bolt pattern using an old sump. Unfortunately in my area (NY) there are no "friendly mower repair guy" who would be that helpful. I believe I located a Briggs & Stratton engine that should work. But I am still unwilling to purchase it unless I am 99.9 percent certain that it has the correct mounting bolt pattern. From a parts list of that Briggs & Stratton engine I found the sump p/n. On ebay I located a used one with the matching p/n. The asking price is a little too expensive, but I will submit a much lower bid. After all, how much of a demand could there be for a used sump with that p/n.

Thanks again for your suggestion.

Ralph

Well, then--how about this:
Using a single thickness of card-board, make a template, or pattern of the frame of your engine,poke in the bolt holes, and spark plug orientation (way it points( then compare it to an engine you would like to use. I'm sure, if you told the guy what you wanted to do that for, he'd surely be helpful. Us "fixers" are mainly helpful, not somebody who is trying to make enough money to afford a trip to Hawaii!
That said--in the past, i have installed B&S engines wwhere i have removed Tecumseh engines, B&S engine where i removed a Kohler, and installed a Tecumseh engine in place of a B&S engine. I have never had to drill any new holes.
Rusty J.

Hi Rusty,

Thanks again for your help. I believe I can get by the mounting bolt issue. There may be another issue to be addressed. This pertains to mounting a remote gas tank. Unlike the Tecumseh engine, the replacement Briggs & Stratton engine gas tank has to be mounted remotely and would probably require a 3qt capacity - same as the Tecumseh tank. With the new engine in place I have very limited space to mount a tank.

I was trying to locate a website that sells remote mounted lawn mower gas tanks and mounting hardware as well as providing tank dimensions and capacities. Do you know of any or have any other suggestions.

Ralph

Just a thought - are your 16 year old mower deck and transmission gonna last long enough to pay for the cost of a new engine?

FYI: I removed a blown up Kohler engine from a simplicity lawn tractor, and replaced it with a B$S engine. Didn't have to drill any new holes. Spark plug faced the same way as the old engine. I mounted a 2 gallon fuel tank on the front of the engine flywheel cover, with some homade brackets, and used gravity to feed the carburetor. Worked good. This summer, i got that tractor back, so i connected a fuel pump into the fuel line, and now use the gas tank under the seat.

Hi
I bought a Crafstman mower in April 2009, and after only 3.5 years of mowing, the engine blew up. It was a 20hp Briggs and Straton. Really disappointed w. the poor quality.

Any ideas on where I can find a worthy replacement?

Engine Model # (xxxxxx-xxxx-xx): 331777 0951 B1
Engine Code # (xxxxxxxx): 080111ZD
Horsepower: 20hp
Thank you

To: Paul 171:
evidently, you didn't check the oil before starting the engine. Oil will stay up high on the dip-stick for hours and or days. It gets high from the engine running. If you just open the hood, pull out the stick and look at it--you will wonder who put so much oil in your engine, because the oil doesn't run off when not in use. And, if you don't wipe it and check it again, one day you will hear an expensive sounding "BANG", and that engine won't run ever again. It happened to my son. He's a lot smarter now, and poorer, too!

Paul171-

Since the engine date code is January 2008, that kind of infers you bought a used mower.
If so, who knows how well it was treated before you got it?

I hate to be mr negative here but you have a mower that is no longer being made as murray also went bankrupt before tecumseh did. briggs bought murray sos there are some parts left but they are getting harder to find (except for the common parts). the amount you will spend on a new engine shoudl be applied to a new mower. you get a warranty and so on. briggs is normally pretty good at supply "will-fit" engines but you do also have to be aware of the wiring and throttle controls. bolt patterns are usually very simmalar between engines.
(sorry for any spelling errors)

I've always had good luck with O'Connors. I saw that bill_kapaun suggested a Tulsa place...If you're in Oklahoma, you might try them. I think they offer parts for riding lawn mowers