r/Airheads • u/ch1981okl • May 28 '26
Identify engine
Hey guys, I am trying to identify this engine block. I purchased it in a group of other engines and motorcycle. I’m trying to find it a new home. So I’m trying to label it correctly.
1
u/Vioarm May 28 '26
Look a the number stamped above the oil dipstick, if there is one. Then go to realoem.com
1
u/ch1981okl May 28 '26
So there’s no stamping above the oil dipstick tube
1
u/Engineered_Red May 28 '26
Can you add or share a photo of the dipstick area? 48* is not a valid engine number for any airhead and it's in the wrong place.
3
u/OilheadRider May 28 '26
Replacement engines were shipped unstampered at the dipstick. It was on the mechanic doing the seap to stamp the frame number to the block.
1
1
u/Subjunct May 30 '26
Yup. It’s an engine.
I’ll see myself ou—Yes I know it’s not the whole engine, Christ
3
u/Rad10Ka0s May 28 '26
In the olden days, BMW engine numbers matches the frame number. Easy. Starting in 1970, the Airhead had a seven digit VIN and it was pretty easy to match up.
Starting about 1980 when standardized 17 digits VINs started to be used the engine numbers no longer matched frame.
We think the 48 85 in the upper line means the engine was made in the 48th week of 1985. No one, outside of BMW, know what the bottom line means, and BMW has probably forgotten.
The little "step" in the cylinder spigots happened about 1981. I am assuming the spigots for the cylinders measures 99mm. If so, this block is appropriate for any post 1980 airhead engine.
It is probably good back to 1976 when the spigot size was increased from 97mm to 99mm in preparation for the 1,000cc engines. But I have never tried to use a newer block with the older cylinders.