Paul L

What were the engine differences between the 396cid engine hp ratings of 325, 350 and 375 hp that were typically seen in 1968?

SuperFast80

Rectangular port heads on the larger outputs and oval ports on the lower ones.

I am going to go out on a limb and say cam too.

Vetterodder

The L78's (375hp) were essentially an L72 with a smaller bore. Solid cam, rectangular port heads, 4 bolt mains, 780 dual feed Holley, 11:1 forged pistons. There was a different 375hp 396 in `65 Chevelles only (and not many) that used a hydraulic cam.

The 350/360hp was almost identical to the L36 427 except for it's smaller bore. It used a hydraulic cam, 10.25 cast pistons, oval port heads, a 580 single feed Holley on early versions, a Quadrajet on later ones.

The 325 hp version was basically the same as the 350hp but with a milder cam and all years used a Quadrajet.

Paul L

That's the answer. In fact more than I knew. Thanks!

Larry B.

I think the Corvette 396 was rated at 425hp. :chevy

Vetterodder

Indeed it was, as were the L78's installed in `65 full size Chevies. The `65 Corvettes were reputed to have more efficient exhaust manifolds than the other cars that would later get the L78 and I believe they had larger exhaust pipes than the other cars also but I don't see a 50hp difference there. More likely, GM chose the lower rating for Chevelles, Camaros, and Nova's due to hostile insurance companies and other critics of "muscle cars". They probably also sought more favorable classifications by the NHRA. Keep in mind that the engineers took the dyno readings but it was the marketing guys that chose what was advertised. They did the same thing with the L72 and the L88. The L72 427 was originally rated at 450hp and then at 425hp with no other changes than the decal on the air cleaner. They just advertised it's hp at 200 less rpm. For the 430hp (yeah, right :)) L88, they really fudged and advertised it's power 1,000 rpm or so below it's actual peak. I had a new 350hp 396 `67 Chevelle and a friend had a 375hp `66 Chevelle. My 350hp car was a strong runner (14.1's pure stock) but I can guarantee that the L78's bigger heads, bigger cam, bigger carb, and higher compression, were worth a lot more than just 25 hp.

Paul L

Thanks! I dreamed of a 375hp Chevelle SS in 1968 but the bank account said no. I settled for a 1964 Malibu SS with a 327 and a four-speed. Wish I had that Malibu today....

Rowdy Rat

I've owned my 1969 L-78 Nova for about eight years or so and it has to qualify as one of the quickest straight line cars (in stock form) that I have ever driven. The 375 hp L-78 is VERY strong and in the Nova body makes for a relatively light weight package at around 3400 pounds. About the only drawback is the shift linkage which is marginal at best... And of course the stock E70-14 tires that always makes launching the car an "interesting" experience.

Of course, straight line acceleration is about the only thing that the car is good at... God help you if you need to stop or turn at anything over highway speeds. :)

Regards,