A friend was telling me about his "new" engine tonight. I'm wondering what the generation splits are among the SBC's. I think I used to know this, but I can't remember for the life of me. What years are compatible with each other?

Thanks!

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ThaDex
1981 Z28
1978 LT

Basically, not much changed from 1955-1985. Then, Chevy changed first the block for 1986, which is kind of a morphodite engine (spelling), and then the heads and top end starting in 1987.

After that, I think they started producing Ford or Honda engines or something like that. http://www.nastyz28.com/ubb/frown.gif

heres the small block generations.

gen 1 1955-1985
gen 2 1986-2000
gen 3 1999-2004
gen 4 2005 +

1999 and 2000 you could get a truck with either genreation engine.

and gen 3 small blocks are incredibly well built despite what people say, i havent had too much experience with gen 4s yet to rate them.

From 1955 to 1985 you could swap around just about any part to and from any small block.

In 86 they went to a 1 pc. rear main seal, and the center intake bolt holes in the heads was at a diff angle. You can still bolt those heads onto an older block, but you just have to enlarge the holes in the intake, or get a 86 or never style intake.

The journal sizes (rod and mains) changed in 1968. 55-67 was "small journal" 2.30" mains and 2.00" rods, then in 68 they went to 2.45" mains and 2.10" rods.

Thanks! I thought there was a change in the mid 80's.

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ThaDex
1981 Z28
1978 LT

<font face="Arial,Verdana" size="2">Originally posted by johnny_rebel:
heres the small block generations.

gen 1 1955-1985
gen 2 1986-2000
gen 3 1999-2004
gen 4 2005 +

1999 and 2000 you could get a truck with either genreation engine.

and gen 3 small blocks are incredibly well built despite what people say, i havent had too much experience with gen 4s yet to rate them.</font>

Sure you're not thinking of the generations of Camaros?

From the first production small block until now (because they're still making them as replacement engines) is a Gen. I block. The one piece rear main seal is still a Gen. I.

Gen. II the LT1, LT4 (Not sure about the LT5 since technically it's a Mercury marine engine), and the L99 engines. The reverse flow cooling and the change in the ignition system is what makes them different.

Gen III engines are the spin offs of the LS1. I'm not sure on production codes but the LS1, LS6, LS2 and (soon to be)LS7, as well as the 4.8L, 5.3L and 6.0L "Vortec" engines (GM needs a catch phrase).

AFAIK there is no Gen IV engine yet.

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350CID, Vortec 062 heads, Magnum 280, Performer Intake, Holley 650 DP, 3.42 rear w/ Auburn posi, 2600 Stall/TC
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