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  #1  
Old 10-11-2017, 02:15 PM
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My 69 L78 was just a basic build,trw pistons,bullet stock spec camshaft,it was balanced.heads are stock 840 castings.with headers it made 415@5500 and 400ft lbs from 2000 to 5500. My nova ran a 13.02 off the trailer at scr with headers 4.10's and street tires
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1969 nova SS396 L78 4 speed triple black survivor
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Old 10-11-2017, 04:10 PM
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When they were 425hp in 1965, that was with the more streamlined Corvette exhaust manifolds that also fit & were used on full-size L78 cars that year. They became 375hp when fitted with Chevelle, Nova, Camaro log-style manifolds. It would interesting to see an exhaust manifold comparison on the dyno.
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Old 10-13-2017, 12:37 PM
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What were the final numbers?
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Old 10-13-2017, 09:08 PM
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For comparison here is an original 1969 L/78 restoration engine I rebuilt last year. All stock except Comp/Cam replacement cam, EDM lifters,+030 TRW pistons and run with shop headers. Fifteen minute break in & one dyno pull 38 deg timing pump 92 octane. We did not jet or do any other tuning as this is the original motor from a SS 1969 Chevelle.
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Old 10-13-2017, 09:43 PM
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Yikes! Thanks for all of the input. We were able to coax a few more HP after re-jetting. Then we put the shop carb on and it woke up! 446 hp at 5700.
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Old 10-14-2017, 02:14 PM
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Quote:
Originally Posted by bergy View Post
Yikes! Thanks for all of the input. We were able to coax a few more HP after re-jetting. Then we put the shop carb on and it woke up! 446 hp at 5700.
Sounds about right.

I installed a 3910 on my 496 for the initial dyno tests and the engine picked up somewhere around 20 when I swapped to a 3418 (`67 L88 855 vacuum secondary). During the last series of tests, the engine picked up another 30+ when I replaced the L88 carb with a 4781 850 double pumper, and another 20 when I switched to a 1000 HP (I built & calibrated myself). That's over 60 HP just in the carbs.

The factory carbs are good, but they do leave room for improvement. Comparing them to a newer "race" type carb really is an apples to oranges comparison.
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Old 11-07-2017, 01:31 AM
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Default 68 nova ss 396

recently I dynoed my 396/375 hp motor for my 68 nova ss matador red car...with lots of tuning through stock manifolds and 520 lift flat tappet camshaft best hp was 465 hp and 455 torque.. Chris teed
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Old 11-07-2017, 01:33 AM
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Thumbs up L78 Horsepower..

Chris...those are very strong numbers with cast iron manifolds....nice job.

-wilma
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Old 11-07-2017, 01:39 AM
1968 nova ss 1968 nova ss is offline
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tom, we built the motor to run purestock drags in Stanton, Michigan yearly race..but, didn't quite make it..alot of little things make a difference..it runs good behind the Muncie and 4 ;10 gear..
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Old 10-13-2017, 10:32 PM
L72Biscayne L72Biscayne is offline
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I built a 66 L78 all stock except for a little head work. It made 444 @ 6000 rpm with headers and a 3247 Holley carb.
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