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#1
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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1967 SS427 4 speed triple black survivor-sold to a good home 1969 nova SS396 L78 4 speed triple black survivor 1970 camaro SS350 citrus green,Dad bought it new! 1968 chevelle ss396 L34 M21 KK rear all born with 1972 formula 400 M22 
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| The Following User Says Thank You to cwc For This Useful Post: | ||
ss396fan (10-15-2017) | ||
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#2
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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1962 Biscayne O-21669 MKIV/M-22 1962 Bel Air Sport Coupe 409/1,000
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#3
10-13-2017, 12:37 PM
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What were the final numbers?
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#4
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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#5
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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#6
10-14-2017, 02:14 PM
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Quote:
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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#7
11-07-2017, 01:31 AM
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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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#8
11-07-2017, 01:33 AM
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L78 Horsepower..
Chris...those are very strong numbers with cast iron manifolds....nice job.
-wilma
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02 Berger 380hp #95 Lots of L78 Novas Join National Nostalgic Nova! 70 Orange Cooler 69 Camaro
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#9
11-07-2017, 01:39 AM
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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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#10
10-13-2017, 10:32 PM
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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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1970 Z28 Citrus green CW 3:73 1970 Ls6 Cy 3:31 14K miles 1968 Biscayne L72 M22 952 actual miles. 1966 Biscayne L72 3:73 1966 Chevelle L78 M22 4:56
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