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Restrictions In 76

  • Thread starter Thread starter Red76Vette
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R

Red76Vette

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What did they do to restrict the horse power in the mid 70’s I have a 76 with a 350 and I am only getting like 180 hp why is that I should be at least twice that. The 70 had a 350 with 350 hp same engine. What mods need be done.

Thanks, Chuck
 
You have smaller valves in the heads, lower compression, restricted exhaust, smaller carb/carb settings, and most of all, a less aggressive cam shaft. Other than that, they are both 350 cubic inches, but the 70 model is pumping more air and thus making more power.
 
How hard would it be to bring his 350 up to a '70s 350 and do all of those mods? I guess if he had a shop and a lot of money (:)) it wouldn't be a problem, right?

TR
 
Red76Vette said:
What did they do to restrict the horse power in the mid 70’s I have a 76 with a 350 and I am only getting like 180 hp why is that I should be at least twice that. The 70 had a 350 with 350 hp same engine.
Chuck,
One of the really major differences is that the 70 was rated at gross HP while the 76 is rated at net HP. Both ratings are on an engine dyno and taken at the flywheel. The gross is without any accessories, open air intake, headers with open exhaust, no emission equipment, no alternator, no water pump, etc. Net is as the engine is equiped installed in the car, full air cleaner assembly, stock exhaust mainfolds with stock exhaust and mufflers, alternator, water pump, and full emission equipment.

The big restriction on the 76 is the exhaust. The single exhaust (2 into 1 into 2) and a single cat converter kills the engine. Also the 70 350hp engine is more like the L82 of later years then your base L48. Liven it up with the normal hot rod tricks, exhaust, cam, heads, etc.

tom...
 
Be careful doing any mods in California! You still have to be able to pass a smog check until the car is 30 years old, and many suggested mods will cause you to fail. Also, your car must have all original emissions equipment, configured exactly as it came from the factory...

Governments started imposing strict emissions controls in the mid-70's. But carmakers didn't know how to effectively (and cheaply) control emissions without sacrificing horsepower. It wasn't until the advent of computers and electronic fuel injection that they were able to restore some power to engines.
 
If I know a guy who will pass it what would be the way to go to make it faster. So far all I have done to it is K&N filter and 40 series flowmasters other than that I don’t what else has been done to it I bought it from corvette mike in California which is a pretty reputable place or so I hear all the people I know have only good things to say. Also how often do you need to replace break calipers?
 
If you're in CA, then the emissions thing is important, so I won't comment on that. As for brake calipers, I replaced both front ones on my '75 when I bought it two years ago, which got rid of my brake fluid leaks & restored my braking to 'normal' (although eventually I'll need to replace my master cylinder and power booster). Once every 25 years or so isn't too bad, I'd say....
 
Re: Re: Restrictions In 76

Tom73 said:
Chuck,
One of the really major differences is that the 70 was rated at gross HP while the 76 is rated at net HP. Both ratings are on an engine dyno and taken at the flywheel. The gross is without any accessories, open air intake, headers with open exhaust, no emission equipment, no alternator, no water pump, etc. Net is as the engine is equiped installed in the car, full air cleaner assembly, stock exhaust mainfolds with stock exhaust and mufflers, alternator, water pump, and full emission equipment.

The big restriction on the 76 is the exhaust. The single exhaust (2 into 1 into 2) and a single cat converter kills the engine. Also the 70 350hp engine is more like the L82 of later years then your base L48. Liven it up with the normal hot rod tricks, exhaust, cam, heads, etc.

tom...
Tom
Thanks for the info I wish I dident have to pass smog. The L82 was not avalable in california and I got a california car The ups and downs of a cali car.

Chuck
 
My friend's dad (owns a C4 '86 beauty) just gave me the Feb. 2003 edition of Corvette Fever, and there's a nice article and methods for getting more power out of the engine. I don't think it's anything you haven't read about on this forum, though.

Just thought I'd mention that. :)

TR
 
Red 76 , one of the things they did , as mentioned , was lower the compression . On my 72 Camaro I changed the heads from the smog heads with 75 cc combustion chambers to service package heads with 65 cc chambers . The larger chambers were said to be 2/3 of the compression drop . You would also get larger valves (I Think) . I live in Indiana though and have no idea what this would do emission wise . We don't have any type of inspections here . Cliff
 
There are a number of manufacturers that have cylinder heads with large valves and 64cc combustion chambers that are smog legal in California. Any after market heads that are legal will have a C.A.R.B. (California Air Resources Board) certification number. The same is true of after market cams. With proper tuning, these products can be used to increase power and still pass the visual and sniffer test.

Heads can cost anywhere from $1200 on up. Edelbrocks can be had for around that price per set, smog legal. Air Flow Research (AFR) has a set for a little more that flow better. The choice is yours. Just make sure to look for a CARB certification.

Good luck!!

Ron
 

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