I have several slant sixes. I would like to be able to tell the cu in by looking for numbers etc. Do the /6s have a location on the block where numbers are stamped? Once, if, I find them which numbers represent which cu in? What year? Gordo

Another Question, I have a 61 Slant six pickup. short wide box 6 foot. On the data plate it says 88 net HP. What size engine and gross hp is this?

88 gross is probably a 170 (maybe 198?) - I believe the 225 Gross was 105 or so

On the passenger side of the valve cover, at the front of the engine - there is a pad of metal that sticks out (just behind the bracket for the coil) with stamped numbers/letters. The three continious numbers are block size. These numbers may of been whiped clean if the block has been previously shaved.

The engine numbers were stamped in different places in different years. Most of the '61-'75 engines had them on a boss (pad) at the top of the engine block (not at the valve cover) under the frontmost spark plug. Starting around '75, this pad was moved to the rear, under the rearmost spark plug. Some engines ('60, some late-'70s items) have the numbers elsewhere on the block.

Between '60 and about '70, the engine displacement was given by two digits. 17 for a 170, 22 for a 225, 31 for a 318, etc. The engine model year was indicated by other parts of the engine number. Before the displacement was a letter indicating the production model year. Q for 1960, R for '61, S for '62, T for '63, V for '64, A for '65, B for '66 and so on up the alphabet. After the displacement was the production month and day. So, for instance:

S22 10 17

means a 1962-model year 225 made on October 17, 1961.

This number format applies to American-built engines only; Canadian engines had a different numbering scheme.

Starting in the very early '70s, the numbering scheme was changed. Among the changes were the use of the whole displacement (198, 225, etc.) rather than the first two digits.

88 net HP would be a 170, which was a seldom-ordered "downgrade" fuel economy option (standard was 225 @ 127 net hp). Gross HP of the 170 in '61 was 101.

The 198 existed only between '70 and '74, so would not be referred to on a '61 truck dataplate.

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Many Thanks. Have more questions I am sure but will glean from the board first. Gordo