Question on '65 L78 vs. later L78s
 

My friend thinks the L78 in the 1966 Chevelle was identical to the '65 L78 in the big cars - I'm talkin' physically, not on paper. I have a suspicion that there was something different, like a carb or exhaust manifolds, that may have been different. Anyone?

I know the Z16 was not an L78, for what it's worth.

Re: Question on '65 L78 vs. later L78s
 

Didn't the Z16 engines have a hydraulic cam. Other than that I understood that they were basically the same. Any other differences probably had little effect on hp output.

Re: Question on '65 L78 vs. later L78s
 

The neat thing about the 1965 Full-Size 395-425 HP cars is that they shared the same "swoopy" exhaust manifolds with the Big Block Corvettes. 1966 Full-Size 427-425 HP cars also shared the good exhaust manifolds with Corvettes. These better exhaust manifolds didn't fit the Chevelle chassis so they used the more restrictive "log" type exhaust manifolds.

Re: Question on '65 L78 vs. later L78s
 

I wouldn't bet those Corvette manifolds won't fit on a Chevelle. We put a pair on Terry Penningtons 69 Camaro F.A.S.T. car just as a trial to see if they would fit and they cleared the sub frame (they were close on the steering but didn't hit) with no problem. You would have to eliminate the heat riser and get a little creative with the exhaust pipe bends, but it could have been made to work. I'm not saying the factory would have done it the way we were going at it, but there is still a possibility. Terry has a 67 Chevelle 4 speed car in his shop right now that's going to get a 375/396, and I'm gonna try a pair of Corvette manifolds on it just as soon as the engine goes back between the fenders..... https://www.yenko.net/ubbthreads/imag...ns/naughty.gif

Re: Question on '65 L78 vs. later L78s
 

[ QUOTE ]
Didn't the Z16 engines have a hydraulic cam. Other than that I understood that they were basically the same. Any other differences probably had little effect on hp output.

[/ QUOTE ]

That is correct, if memory serves me, it wasn't coded L78 either.

Steve

Re: Question on '65 L78 vs. later L78s
 

[ QUOTE ]
[ QUOTE ]
Didn't the Z16 engines have a hydraulic cam. Other than that I understood that they were basically the same. Any other differences probably had little effect on hp output.

[/ QUOTE ]

That is correct, if memory serves me, it wasn't coded L78 either.

Steve

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They were the L37...Suffix IX..

https://www.yenko.net/ubbthreads/imag...lins/beers.gif
~ Pete

Re: Question on '65 L78 vs. later L78s
 

Hey, guys, thanks for the responses, but we're talking L78s here. https://www.yenko.net/ubbthreads/imag...mlins/haha.gif https://www.yenko.net/ubbthreads/imag...lins/beers.gif

Re: Question on '65 L78 vs. later L78s
 

The only difference I know is the 65 block has no oil groove in the back cam journal. The 65 cam has a groove all around the back journal. The 66 doesn't. The 961 was the 2-bolt and the 962 was the 4-bolt for both 65 & 66. The chevelle vette and Imp all used the same intake the 963. The carbs were the same cfm, just diff. #s. The heads 208 & 858s same valves 2.19/1.72 and same size combustion chambers 108.989.
Piston weight was diff 24.00 oz. to the 66 piston 23.13 oz.
I don't know of any differance between them.
That's my story and I am going to stick with it!!! https://www.yenko.net/ubbthreads/imag...mlins/haha.gif

Re: Question on '65 L78 vs. later L78s
 

So the exhaust manifolds are diff or the same? You seem to know a lot about 'em but you didn't mention this.

Re: Question on '65 L78 vs. later L78s
 

Here's what 396/427 Chevelle/Camaro ex manifolds look like.

https://www.yenko.net/attachments/453...velleexman.jpg

Re: Question on '65 L78 vs. later L78s
 

These are the style used on 65 and 66 Impala, Bel Air and Biscayne 396 425 hp and 427 425 hp engines. These are the same style used on 65 thru 69 396 and 427 Corvettes.

https://www.yenko.net/attachments/453076-427exman.jpg

Re: Question on '65 L78 vs. later L78s
 

I think you would be hard pressed to get the Vette style manifolds in a Chevelle chassis, especially the passenger side. Headers go back to about the third exhaust port before they turn down to clean the cross member. It would be nice if they did.

Re: Question on '65 L78 vs. later L78s
 

Why bring it up they all ready did. I don't know. https://www.yenko.net/ubbthreads/imag...lins/dunno.gif https://www.yenko.net/ubbthreads/imag...mlins/haha.gif https://www.yenko.net/ubbthreads/imag...s/rolleyes.gif

Re: Question on '65 L78 vs. later L78s
 

65/66 L78
Same block, bore, crank...
Different pistons, Cam, heads, intake, carb, distributor, and exhaust manifolds

In Aug of 65, GM rated the 66 L78 at 425 and 6200rpm. Rating was later dropped to 375 at 5600rpm.

Jack Douglass Chevrolet actually received shipment of 25 or so 425hp rated 66 L78. Same motor, just a different rating at a different RPM. Documented 425hp rated 66 L78 are known to still be around.

Re: Question on '65 L78 vs. later L78s
 

The block cast #s are the same, but the machine work is diff. Don't put a 66 cam in a 65 block. Run it about 10 mins. And you will have a very heavy paper weight!!