I have my 23 engine apart to replace the mag ring.
I thought that I should check out the engine as
I know nothing about it. I find the Babbitt to be
very nice and the rods to be standard. The bore is worn about .003 with no scuffs or marks. It has the original cast iron pistons. Should I replace the pistons with AL or just put rings on the original pistons?
Three thousandths, in my opinion, is not enough clearance for aluminium pistons. IF it were mine, I would jump for joy at having an original engine with slight wear, and ring the original pistons.
Yes, I know Ford made .003 oversize pistons, and these were for just this situation.
IF you are building this for high -use, high speed running, then machine work and aluminum pistons are the way to go.
I would have a machinist hone it to .010" or .020" oversize so the bores are straight. You would not need to replace the Babbitt if it is as good as you say. The block can be power washed after boring and it will be fine.
You did not say where the oversize condition is, but typically it is going to show up as taper, with wear in the middle of the bore. That means the rings get a real workout, and you are wasting your time trying to keep the old tired pistons.
If you installed standard size aluminum pistons then you will still have too much clearance in the center of the bore. So that would be a waste of time and money too.
I have a nice running engine in my Coupe with twice that clearance and Cast Iron pistons. I put new rings in it. It runs well and starts easily. There is less power but I find it nice to drive around town. It could last a long time depending on how you want to use it. However, if the engine is down now might be the time to upgrade it.
I don't see any mention of the clearance, only the wear.
Unless it was using oil, I wouldn't mess with it! Just finish replacing the mag ring!
Good point Royce. My Coupe motor had .008 to .012 thousands of an inch clearance in the cylinders.
The pistons measure 3.745 on the thrust side. the bore is 3.751-3.753 0nly 6-8 thou clearance.
Is this too tight for AL pistons?
Is the oil control ok with the 1/4 wide oil rings?
While you where taking it down, did you find the cause of you band engagement problem.
Yes the rev drum was badly scored and the bands were glazed and worn out. Two of the brass screws that hold on the magnets are busted off, and the plates came off. Everything was full of lint from old bands, hands full like mouse nests. Everything else was like new. Going to replace the valves and lifters and rings I think. Must be a low mil engine, the whole car has been messed with very little.
Sounds great, also good you took it apart and now know exactly what shape everything is in. If you need a hand I have more time starting next Wednesday. Will have Wednesday and Sundays off.
Thanks Dave, but I have a locale person helping me at this time. I really appreciate the offer. Maybe at another step in the process.
No problem, if anyone is close I always offer! Hoping to have my speedster chassis complete and running for the April meeting. I plan to trailer it up.
Since you are redoing most everything else, I think I would rebore it 0.030 and install aluminum pistons. Then you should be done with engine work for your lifetime.