whats the difference between an B18 "b" and B18 "d"? how do you tell?
I know one has 8.5-1 the other has 9.5-1 compression

Depending on the year, some of them also have a different cam.
There will be a motor type number on the side of the block, starting with 4968 and
several more digits. If you post the first 6 digits I can tell you which type
and
which cam it had. The first digits are cast and the rest are stamped in a rectangular
boss next to the cast numbers on the left side of the block at the top above the dipstick.

thanks but car is gone now, so no way to get no's

engine is in car, gone!

George is asking for numbers on the engine block, not the body. Look at his post again and you'll see what I mean.

Are you're saying you have the cylinder head from this unidentified motor and want to know the compression ratio? Measure the deck height--the distance between the machined surface for the valve cover and the bottom of the head. I don't have the specs but someone on the BB will. The difference will be something like a few mm. -- Dave

From memory...

The low-compression B18A/D head is 3.465" thick.

The high-compression B18B head is about 3.390" thick.

From the factory shop manuals, here are head thickness vs compression ratio numbers for a variety of B18 engines:

88.0 mm (3.465") = 8.7 - B18D
87.0 mm (3.425") = 9.5 - B18B early (type 1)
86.2 mm (3.394") = 10.0 - B18B late (types 2,3)

There are small inconsistencies across manuals, dependent on year of publication. The above numbers were taken from the B18B/D manual published 3/69.

Pretty good memory, Phil... we'll forgive the .004" error! :-)
--

Gary L - 142E ITB race car, 73 1800ES
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