HydroPuddle
Member
I have a 1943 Ford 9N. I have taken the engine all the way down to a bare block and I am ready to purchase new bearings all around. The shop manual (Paragraphs 40-43) is very handy when it comes to describing how to check if you need new bearings but it's a little unclear to me when you plan on replacing them regardless. There is some wear on the middle main and it may be Ok but I don't want to put this thing back together without fresh bearings.
I checked for out of round at the bearing surfaces on the crank and all are within spec and are less than .0015 inches out of round when doing the four measurements as described in the shop manual
Somebody has for sure been in this engine in the last 70 years, there must be four different types of valve manufacturers in there and I suspect due to the generally good condition of the bearings themselves and the uniformness of the crank, it may have been ground in the past.
To start, and as reminder, the stock tolerances direct from the manual...
Stock Mains: 2.248-2.249 inches (57.10-57.12mm)
Wear limit: 0.005 inch (0.13 mm)
Stock Rods (Crankpin): 2.0935-2.0945 (53.18-53.20mm)
Wear limit: .005 inch (0.13 mm)
This is what I measured on my crank...
My Main Front: 2.230 inch (56.65mm)
My Main Mid: 2.230 inch (56.65mm)
My Main rear: 2.231 inch (56.67)
Rod 1: 2.0767 inch (52.75mm)
Rod 2: 2.0763 inch (52.74mm)
Rod 3: 2.0755 inch (52.72mm)
Rod 4: 2.0755 inch (52.72mm)
I just want to make sure I got this right. If I subtract my measurement, from the the tolerance on my front main I get...
2.248 (low stock) - 2.230 (My Front Main) = .018
2.249 (high stock)- 2.230 (My Front Main) = .019
The question is... Which main bearing kit size should I buy? .010, .020, .030? Should I suck it up and pay somebody to grind the crank?
Thanks in advance...
I checked for out of round at the bearing surfaces on the crank and all are within spec and are less than .0015 inches out of round when doing the four measurements as described in the shop manual
Somebody has for sure been in this engine in the last 70 years, there must be four different types of valve manufacturers in there and I suspect due to the generally good condition of the bearings themselves and the uniformness of the crank, it may have been ground in the past.
To start, and as reminder, the stock tolerances direct from the manual...
Stock Mains: 2.248-2.249 inches (57.10-57.12mm)
Wear limit: 0.005 inch (0.13 mm)
Stock Rods (Crankpin): 2.0935-2.0945 (53.18-53.20mm)
Wear limit: .005 inch (0.13 mm)
This is what I measured on my crank...
My Main Front: 2.230 inch (56.65mm)
My Main Mid: 2.230 inch (56.65mm)
My Main rear: 2.231 inch (56.67)
Rod 1: 2.0767 inch (52.75mm)
Rod 2: 2.0763 inch (52.74mm)
Rod 3: 2.0755 inch (52.72mm)
Rod 4: 2.0755 inch (52.72mm)
I just want to make sure I got this right. If I subtract my measurement, from the the tolerance on my front main I get...
2.248 (low stock) - 2.230 (My Front Main) = .018
2.249 (high stock)- 2.230 (My Front Main) = .019
The question is... Which main bearing kit size should I buy? .010, .020, .030? Should I suck it up and pay somebody to grind the crank?
Thanks in advance...