dpwrr

In 1975 I purchased a used complete engine in Brooklyn, NY. I was told it was from a 69 or 70 Chevelle and it was a HP 402. I rebuilt it using quality 402 rings and bearings and every went fine. It has 4-bolt mains, rect. port heads, and a holley tri-power setup. It also has a solid lift cam. I beleive it to be all original when I bought it but I can't find any verification that chevy ever sold the tri-power on a 402 in a Chevelle. I know thet back then it was possible to special order custom engines. I haven't looked at the number codes yet but any additional help would be great.

ProStreet67

Tri-power was an option on the 427 Corvette only and was very rare.The 402 formally replaced the 396 engine in 1970 as the last year for the 396 was in 1969, and as far as I know, the 402 wasnt considered a Hi Performance engine, as the LS6 & LS7 454's came out in 1970 as the High Performance Engine options. Also I dont beleive the 402 had rectangular port heads, more than likely oval port heads.

The Hi Performance 427 also ended its reign in 1969 also. A 427 was available in the 70's in a standard and a tall deck block version, and all these were in trucks and were not Hi Perf engines or platforms. The 327 also ended in 1969 and the 307 took its place. In 1970 Chevy also introduced the 400 small block in both 2 and 4 bolt main versions. By 72/73 the 4 Bolt 400's ceased production with the 2 bolts continuing till 1977 when they ceased production.

The 402 was an optional lower perfromance engine in the big block line up. The 402 saw alot of use in larger cars such as station wagons and trucks. It was probably an option in the Chevelle to get into a big block. Basically a 402 is a .030 396 Block. Every .030 adds 6 cubic inches basically to an engine when over bored. By 73/74 maybe 75, the 402 was gone too.

Anything considered a Hi Performance Block/engine/head was stamped Hi-Perf above the oil Filter Pad on the Engine and in the rocker arm/stud area in the heads, and also the back of the block that is usually covered over by the transmission bellhousing. If you dont see Hi Perf on a block or head, it more than likely wasnt a performance part.

To get a actual answer, I would suggest running the block numbers to see what you actually have. My wifes family owned a Chevy dealership for almost 40 years and I was told alot of what I have mentioned herein direct from a dealers knowledge and perspective.