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Old Jan 5, 2016 | 11:51 AM
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Default 79 Virgin

I decided to look for a winter project and maybe help a friend to get her first corvette. I found a 79 with L48 with 47K original miles. I am not sure if it's a dilemma or just want to removed all the stock system.
It still has all the vacuum emission stuff and all the factory covering for the plug wires.

What benefit does the factory vacuum system on the intake manifold that controls the EGR and the valve on the passenger side exhaust manifold.

I am planning on removing all of that and also switching to an open type air filter vise the dual snorkel stock intake. Is this something beneficial or keep everything? Thanks in advance
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Old Jan 5, 2016 | 11:58 AM
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Do you have to pass emissions testing?
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Old Jan 5, 2016 | 02:20 PM
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Originally Posted by Easy Mike
Do you have to pass emissions testing?
No... No emission requirement to meet.
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Old Jan 5, 2016 | 02:33 PM
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You can disconnect whatever you like, but you will not be gaining any horsepower, if that's what you're hoping. Swapping to the open element air cleaner will also not help much on its own.

Why not leave the car as it is, tune it, and drive it for a while before deciding what you want to do with it? You may you like it as it is.

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Old Jan 5, 2016 | 03:00 PM
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Originally Posted by Easy Mike
You can disconnect whatever you like, but you will not be gaining any horsepower, if that's what you're hoping. Swapping to the open element air cleaner will also not help much on its own.

Why not leave the car as it is, tune it, and drive it for a while before deciding what you want to do with it? You may you like it as it is.

The stock exhuast is all rusted with holes on the pipes to the muffler. There's a "butterfly" on the right bank exhuast manifold. Is this something I can eliminate when I install the new dual exhaust system? there's a vacuum pot attached to the butterfly. What's the function of it? I do like the way it is, I just thought removing any restriction would help the efficiency.

Last edited by newbie2vette; Jan 5, 2016 at 03:01 PM.
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Old Jan 5, 2016 | 03:44 PM
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Originally Posted by newbie2vette
The stock exhuast is all rusted with holes on the pipes to the muffler. There's a "butterfly" on the right bank exhuast manifold. Is this something I can eliminate when I install the new dual exhaust system? there's a vacuum pot attached to the butterfly. What's the function of it? I do like the way it is, I just thought removing any restriction would help the efficiency.
That is the heat riser valve that is supposed to help the car warm up more quickly by diverting some of the exhaust under the intake manifold when the engine is cold. Mine was stuck closed and for that and other reasons I disabled it. I also switched to a 2 inch dual exhaust with no catalytic converter.
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Old Jan 5, 2016 | 04:01 PM
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Hi n2v,
It might be wise to get a Chassis Service Manual for this car so you'll have some idea what the various parts do and therefore what else might have to be done when parts are removed.
They might be various implications that won't be immediately obvious.
I'd think you wouldn't want to affect the drivability and reliability of the car since it since it seems like it might be going to someone else who's then going to have to maintain it.
Regards,
Alan
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Old Jan 6, 2016 | 07:43 AM
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Originally Posted by Alan 71
...It might be wise to get a Chassis Service Manual for this car so you'll have some idea what the various parts do and therefore what else might have to be done when parts are removed. They might be various implications that won't be immediately obvious...
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Old Jan 6, 2016 | 09:45 PM
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Originally Posted by newbie2vette
I decided to look for a winter project and maybe help a friend to get her first corvette. I found a 79 with L48 with 47K original miles. I am not sure if it's a dilemma or just want to removed all the stock system.
It still has all the vacuum emission stuff and all the factory covering for the plug wires.

What benefit does the factory vacuum system on the intake manifold that controls the EGR and the valve on the passenger side exhaust manifold.

I am planning on removing all of that and also switching to an open type air filter vise the dual snorkel stock intake. Is this something beneficial or keep everything? Thanks in advance
It won't ever look 'clean' like the engine compartment of the Vette in your avatar. I'm with the others… make it run well first, and fix what you have to fix. As you're doing it, you can clean it up (wire brush, prime & paint) here and there. If it helps, The Corvette Central dual exhaust works well and bolts right up to the old exhaust manifolds.

The dual snorkel is an early version of a cold air intake. If all is intact, I recommend keeping it also.

Good luck and try to enjoy the beauty of the C-3.


Last edited by G-Sting; Jan 6, 2016 at 09:49 PM.
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Old Jan 7, 2016 | 01:10 AM
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I also live in a state that doesn't have emission testing for cars this age. However, that doesn't mean it's legal to remove the equipment. It's a crime under both state and federal statutes to alter emission-related equipment in any way. It is also a crime to sell a car that has been so altered. Inspectors here don't generally check under the hood, so lots of hot rodders get away with it. The first time a curious inspector decides to look though, you're hosed.
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Old Jan 7, 2016 | 01:26 AM
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My 78 is 2nd place for the fastest car I've ever owned, running the 78 L-48 single snorkel air cleaner.

Forward acceleration feels comparable to a 2002-2004 C5 Z06. The dual snorkel would only be better.

IMO, the only reason to get rid of the dual snorkel air cleaner is because you really need the hood clearance. The only better option I know of is the L-88 setup, which also draws cold air.

I do think axing the heat riser valve will help w/ power. The rest of the emissions components, not so much.

Last edited by Shark Racer; Jan 7, 2016 at 01:26 AM.
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Old Jan 7, 2016 | 06:57 AM
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Originally Posted by Shark Racer
My 78 is 2nd place for the fastest car I've ever owned, running the 78 L-48 single snorkel air cleaner.

Forward acceleration feels comparable to a 2002-2004 C5 Z06. The dual snorkel would only be better.

IMO, the only reason to get rid of the dual snorkel air cleaner is because you really need the hood clearance. The only better option I know of is the L-88 setup, which also draws cold air.

I do think axing the heat riser valve will help w/ power. The rest of the emissions components, not so much.
Thank you everyone for the great inputs: I've considered all of them, expecially the dual snorkel. This is going to be a gift, hence I am trying to make sure it will be reliable to enjoy vise being worked on.

The re-build start today, all the parts to re-build both trailing arms arrived last night and the new yoke and half shaft. I even elected to go with the composite spring.

As far, as the dual exhaust. A kit is on its way.
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