Lawn Boy D engine lower bearing replacement

bill7263November 22, 2013

Hi,
I am in the process of overhauling a a D engine on a 1974 model 7263 Lawn boy. I have read in previous posts that you can bore out the bottom bushing and install an F series needle bearing. Can anybody tell me where i can get the information to do this? Maybe some pictures. I have access to a Bridgeport.

Bill

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Mike72

You can use several different needle bearings for this conversion. Lawn Boy used 679277 in the 5006 which was the last D model they made. The needle bearing was pressed in from the seal side. You will have to bore out part of the bronze bushing to do this. Also you will have to bore all the way through enlarging the remaining section of bushing about .020 so the crankshaft no longer rides on it. You want a tight press fit and make sure the bearing does not bottom on the shoulder. When setting up its best to center on the opposite bore where the armature plate fits.

    Bookmark   November 22, 2013 at 5:44PM
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bill7263

Thanks, that is the information I was looking for. Couple questions. The bushing has two holes drilled in it which appear to be for lubrication. One goes to the inside case and the other to the space between the carb and the needle valves. Will these holes be blocked by the mod and are they necessary to keep open?

    Bookmark   November 25, 2013 at 10:26AM
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Mike72

The two holes need to be kept open. The upper one allowed oil which collects at the rear of the crankcase to reach and lubricate the bushing which will now be a needle bearing when you install it. Keep the other hole open also. Make sure the needle bearing when installed is below these two holes. By boring the remaining section of bushing .020 oversize the crankshaft will no longer touch and oil can reach the needle bearing through this space. The bottom end of the needle bearing with the bearing number should face out and be flush with the crankcase seal shoulder. Always press needle bearings from the numbered side.

    Bookmark   November 26, 2013 at 7:23AM
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