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model a flywheel housing to block


Guest johnny cermak

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Guest johnny cermak

Hello,

I am rebuilding my first model a motor and remembered when I took the flywheel housing off the block that there were some shims between the two. I didn't pay much attention to them when removing it but now that I am ready to install I wish I had paid a little more attention to it. I purchased new shims but not quite sure the gap it needs to be and on which bolts??

Anybody have some input or diagrams for me?

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It is a necessity that the housing is mounted correctly so the transmission drive will line up properly. That's what the shims are for. There are several articles listed in the Model A restoration guide books as to how to do this. You should use a dial indicator to make sure that the housing is square to the crankshaft flange all around. If it gets twisted it won't line up correctly. If you can't find an indicator set you can make a home made gauge. Take a piece of 1/4 x 11/2 flat steel and bend it in a "Z" shape so that when mounted to the flange it will hang out over the housing edge. Make sure that it clears the housing so it can rotate. Make one end the width of the crank flange and drill 2 holes in it matching the holes across the flange the same dia. as the flywheel bolts. Install the housing to the engine with the gasket and torque the bolts to 55 ft.lbs. (do not install the 2 upper bolts) and the bar onto the flange with 2 of the flywheel bolts.You may have to use some washers as shims to get it to fit right. Mark the spot on the bar that is directly over the outer rim of the housing and drill a 1/4 hole in the center. Take a 1/4 carriage bolt long enough to make contact with the outer rim of the housing, spin down a 1/4 nut and insert the carriage bolt so the head faces the rim of the housing. Make sure you use a bolt with a smooth head. The first nut you put on will serve as a lock nut. Install another 1/4 nut on the carriage bolt and snug it up finger tight. . Now adjust the carriage bolt so that there's about .030 of clearance using a feeler gauge and tighten ie securely. . If everything is right ,the gap should remain the same around the entire housing. Spin the crank taking readings at intervals around the housing. Note the readings . Try only to gauge the flat areas not around bolt holes. Go around a couple of times and check the readings. If each reading is within 2 or three thousandths of each other you should be good. Generally , they should be. Now install the throttle bracket and the bolts but don't tighten them yet. Place one of the shims over each bolt behind the housing ears and tighten the bolt. Now ,with the gauge, check the top area again to see if there is any change. If there is a large change at the top bolts you will have to add another shim and check again. The shims make up the difference of thickness of the housing gasket. The aim is to get the housing mounted within a few thousandths all the way around,particularly at the top. If you wish to remove the throttle control, make note of how many shims you used so that they can be installed later. There is a thorough article with diagrams in the volume 4 "How To Restore Your Model A" book available from any Model A supplier. Good luck. It isn't as involved as it may sound but it is important. The flywheel should also be check in a similar manner after installation.

Edited by jpage (see edit history)
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