L-78 engine Birth date

[WILMASBOYL78]

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I recently had a 70 L78 rebuilt dead stock except for a .030 overbore (70 396'a started life as a 402) 11:1 compression (verifed) nos 143 cam, 569 intake, 4557 holley, stock distributor, stock, uncut heads (hardened seats)stock valve size. Motor was pretty much clearenced and balanced. 422 hp @ 5900 WITH headers, 400 lbs torque on the Dyno. Everything is essentially the same as the 65-69 L78 except the intake (flatter, slightly lower performance) and the I think the 291 heads (70) may have had slightly larger valves vs. the 840 and also what equates to a .060 over bore over an actual 396 inch motor WITH headers, so who knows for sure..

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Is that with the turbo on high???

wilma

[JRSully]

Headers is the key there Thomas, I expect new upholestry in the Black Beater next time around, fun time though, I must say SULLY

[nuch_ss396]

Hey guys,

This was posted over on the NCRS forum in regards to this topic:

The 1965 Corvette L-78 and the 1966-69 L-78 used for Chevelles and Camaros were, basically, the same engine. All internal parts were exactly the same or, essentially, the same. Ignition and carburetion was different but, essentially, the same (e.g. obviously the Corvette and Chevelle/Camaro applications would use a different distributor since, with just a few very minor exceptions, only Corvette used a tach drive distributor). Intake manifolds were different but, essentially, the same.

The real differences between the applications was, as has already been mentioned by others, the exhaust manifolds AND the RPM that the engines were rated at. The latter was the biggest factor in the horsepower rating difference.

By the way, the 1965 L-78 used in passenger cars was exactly the same as the L-78 used in Corvette EXCEPT for the distributor. The exhaust manifolds were the same and the engines were rated at the same RPM.