LB
Things got a bit interesting in late 1935 since Ford produced two similar V8 engines with different main bearings at the same time. In 1935 Ford started insert main bearings with what are now know as “LB” engines. The LB motors feature replaceable main bearing inserts. LB production started during the 1935 model year and continued in increasing numbers through the end of 1936 model production along side Babbitt main bearing engine production (both occurred at the same time). The main bearing diameter was increased to 2.399” on the crankshafts used in LB motors. LB blocks are visually identical to 35-36 blocks except for wider spacing between main bearing retaining studs, measuring approximately 3 ¼” instead of the previous 3”. Some, but not all, LB motors have “LB” stamped on the top surface of the block near where the intake bolts on. I would not use that stamping as positive identification as an unscrupulous person could have added it to a more common Babbitt motor at some time in the last 80+ years.
Features of the LB block that can be used for identification are:
- 21 studs retaining the cylinder heads
- Water pumps in the cylinder heads
- The water drains are angled
- Passes the pencil test
- Core plugs in the oil pan rails
- Crankcase ventilation
- Insert main bearings 2.399” diameter retained by studs (stud spacing approximately 3 1/4”)
For USA production the outside of the LB motors look identical to the 35-36 engines. This picture shows the front of an LB block.
Here is a picture of the valley of an LB with a better view of the crankcase ventilation tube introduced with 1935 production
Assembled motors may be ruled out as being LB motors by very close examination of the distance between draft on oil pan and front main bearing area of oil pan. The front of the oil pan is a bit wider to clear the larger main bearing caps. The space between the crankcase vent on the oil pan is much smaller on the LB motors, see picture for comparison with the insert motor pan on the left and the Babbitt motor pan on the right. I do know know if an insert bearing oil pan will fit and work on a poured bearing block, so I cannot recommend using a later oil pan as a positive identification of an insert motor on an assembled engine.
