Model A block and engine rebuild question

mkmskm

mkmskm

Senior Member
While at a local car show I stuck up a conversation with a gentleman who had a nice '48 Mercury and during the discussion he asked if I knew of anyone who wanted a Model A engine. Oooh - pick me, pick me!! So last night I brought home in the truck a complete engine with the flywheel and housing. He knew the history of the motor for the last few decades. It had been in a little shortened chassis speedster and then when the owner died, it was just left and it was finally given to him. He plans to rebuild the chassis with a small flathead V8. The engine is partially disassembled. I have the coffee cans full of pistons, rods, 2 Marvel carburetors.... its all there. The block is stamped A488__XXXX and there is a good 1/4" between the A488 and the last 4 numbers. I don't see any obvious cracks in the block and it looks like its been sleeved back to std. A quick bore check with my caliper was 3.86x on all 4. There is light to medium surface rust on the cylinder walls, same with the crankshaft. Everything turns free and the valve train works. I'd like to tear it down and have it rebuilt - what should I look for, be concerned about? Can the sleeves be bored .020" to remove the light rust so see if they can just be honed up? Suggestions for getting the head bolts out?
 
If the block is sleeved as you mentioned then they can be safely bored to .020" oversize. Usually sleeves can be bored out to still have a .060" wall.
The one thing to be aware of is if they left a step at the bottom of the cylinder when they installed the sleeve. If not I would have the machine shop pin the sleeves so they don't decide to go for a walk when the engine heats up. "Since you don't know any history of how the work was done"

In regard to getting the head studs out I have had great luck with "PB blaster" just keep soaking them and let it sit.
 
Yes, I can see the step at the bottom, part of the reason I could tell it had been sleeved. My only other main concern is the surface rust on the crankshaft journals, hopefully the crank is still usable. I put Kroil on the studs and around the pressure plate last night. The first thing I need to do is get the thing down to the bare block so I can handle it better. As luck would have it my 6' 2" son just headed off to college, and with it my source of cheap muscle. :)
 
Can you post a picture of the step at the bottom. If it has the locking step that J&M mentioned, then you should see the sleeve end before the bottom of the cylinder and a step of the original cylinder supporting the bottom of the sleeve.

If you are looking into the block from the bottom and see part of the sleeve coming down a bit more than the block, then you can tell it's been sleeved, but it isn't locked by a step, as J&M mentioned. This seems to be the way most sleeves are installed, but I would want mine locked by a step.
 
I'll post a photo tonight, but how you describe it, mine would be the latter where it extends past the bottom slightly so its probably not stepped.
 
I would hone the bores with a deglazing hone or ball hone, and polish the journals with fine abrasive cloth, and see how they look. Mirror-perfect on journals, and uniform matte crosshatch on bores, would be nice to see, but minor discoloration and tiny pits won't hurt anything. It the surfaces look decent, then do careful measurements with proper tools. If the dimensions check out, then start looking at the babbitt. You could get lucky.

Joe
 
I agree with Joe, and if you are lucky the sleeves will never move. If they were installed with the proper interference fit, they should be OK. After honing the cylinders I like to clean them with gasoline and oil them. Let them set for several minutes or even overnight, then wipe them out and reoil them again. Keep doing this until you can wipe a white paper towel in them and have it come out clean.
 
I rarely step the block when installing sleeves, and have never had a problem. When running, the sleeve would heat up more than the block due to it being "in the fire" and the block cooled by water. I would hone with a rigid type of hone, this straightens the bore, a ball hone looks pretty but cleans the valleys as well as the ridges. If the babbitt is good, just polish the crank with fine emery and go for it. The cam can be polished too, but is more difficult to do, a fresh cam may be in order. Measure the lift, many cams are re-ground to the wrong spec.
 
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