Hi DeeVeeEight ( and all the other Vetter fans there, of course)

before posting a new question about carbs, you have to know that the gasoline price in Italy is incredibly high : 1 liter =1,30 Euro=1,90 USD!!!! considering an average gas consumption of 4km/L , let's say that to drive a Vette here for 30km=50 miles , costs 14 USD.
I suppose you spend at least 2/3 less...

And now the question...
Is there any carb that with a SIMPLE and FAST adjustment enables me to choose between a lower and higher gas consumption? There could be days in spring that I want to drive fast , but also days In summer in which I expect an almost everyday use of the car.

Are carbs provided with adjustable secondaries ( Edelbrock AVS for example) somewhat suitable for the operation above?

-getting new tires. the availability of american tires here is not easy and not a great choice. I've found Goodyear Eagle gt+4. what do you think? I can have Cooper Cobra too...

-when you talk about HP on vette engines ( I'm referring also to the tech literature of companies such as Edelbrock) , I suppose that the power is measured at the engine output , not at rear tires. If so , which is the average power loss , If we want to measure HP at rear tires? If I'm not wrong nowadays sport cars HP values are always intended at the rear gear ( tires) not at the engine output ( sorry if I don't use the right tech words). I'm somewhat trying to compare the Corvette HP with a Porsche, etc....

greetings from Italy
Aldo

 

Tires? Yup, Cooper Cobra Gt's is my choice, and has been for years.
I've gotten over 60g miles onthem.

 

Carbs: Can you lockout the secondaries on the Edelbrock? I know you can on the Qjet.

Tires: I'm partial to BFG Radial T/As.

HP: US cars are rated at net Hp which is flywheel with all of the accessories attached such as power steering, A/C, alternator, water pump.

 

Aldo,
I've been reading your posts this morning and firstly, your use of the english language is just fine. Alot of people here in the States would love to be able to write the english language only nearly as well as you do. Everything you've said here on the forum is perfectly understood, infact I have to laugh as I read due to the fact that it amazes me how well you do with english. Surely you've had some extensive practice with english at some point. What a great ability for a person to have, two languages spoken and even written so well...
Your 'Vette looks great. It's clear that you have some knowledge as to auto mechanics. You mentioned; how/where horse power was rated, at the crank shaft or rear wheel. I really don't know if there is a fine line where a certain percentage of horse power is lost between the crank and the drive wheels as overall drive tranes differ so. Someone on the forum may have some kind of figures for C3 Corvettes with either standard or automatic transmissions. A good healthy engine is one thing, but how the power is transfered to the ground is important as well. Horse power has to be usable in order for it to be worth anything as far as performance goes. It sounds like your engine has afew goodies in it already and with alittle fine tuning your 'Vette will be just fine performance-wise. After working on the suspension and getting some good tires, you ought to beable to come out of corners hard and accelerate quicly up to speed, which is probably what you want with the roads in your part of the world. I would think that the small block, as opposed to a big block, is better for you as handling is much better with a lighter front end. It looks to me, Aldo, that you only have some small work and tuning to the engine and alittle suspension work in order to get your 'Vette in pretty darn good mechanical condition. After that, you'll be ready for the cosmetics.
For spark plugs, I always buy the cheaper ones and file the negative electrode back where it's half way over the positive electrode, where the edge (line) splits the circle (positive electrode) right in the middle. This gives you a wide strip of fire instead of a thin little line. This little trick even makes it hard for an oil-burning engine to foul a plug.Funny that you mentioned NGK plugs, as I just bought NGK plugs two weeks back and filed them back with my Dremmel. They were the cheapest thing in the store and they run like a champ. I don't know if your inspections are very strict, but another trick is to use the gas tank vent line as a return line for you fuel. This will require an electric fuel pump and regulator. You "T" the fuel line off just before it goes into the carb and using the vent line, which is just the right diameter, set up the fuel return from there back to the tank. This keeps the fuel from sitting there and getting hot waiting to go into the carb. The reason for the electric pump and regulator is that you drop pressure with the "T" which youhave to make up for. To vent the tank you just get a vented cap. This works great as it's clean looking and like I said, the small diameter of the vent line is the perfect size. Ofcourse, you can also use a "Cool Can" in combination with this. Keeping the fuel cool is important for performance.I've filed the spark plugs for every vehicle I've had and every time for the past twenty four years, since a guy named Bill Carter showed me the trick. He was the best machinist and engine builder I ever knew. He set afew marine speed records in different classes of boats and had sent gas model airplane engines, which he hand made the pistons, rods, crank shafts, heads and engine casings for to world meets using an off-set bore which he used on automobile engines getting thirty percent more efficiency. In some of the more radical off-sets he did, one side of the piston would stick up past the block deck and he'd trim the piston and cut eye-brows in it for the valves to clear. Those off-set small block Fords and Chevys would run seven and eight thousand rpm with relatively small cams and never stop making horsepower, even after a considerable amount of torque drop-off. I had him machine an off-set 351 Windsor for me in the early '90s. The Windsor head bolts are further away from the cylinders than the others making it possible for more off-set of the bore. He also build me a set of heads with big stainless valves and matched the heads to a ported Victor Jr. intake hedid, matched the performance Fel-pro intake gaskets. I put the engine in a '66 T-bird. I never had a faster and especially smoother and cooler running small block ever. When we moved back from Puerto Rico, I found out that Mr. Carter had died five months prior. He was 84 years old. I learned so much from him! Anyway... The fuel return I've used on quite afew of my cars also and it's easy and quick and works great.
Quite enough for now...By the way, Aldo, those are great quality pics that you're posting.

 

Speakin' of cutting back the electrode, my Dad showed me that trick when I was racin' oval track. Another trick to that, is to round off the electrode, so that the end has no sharp edges. This is a trick he used on military aircraft in WWII. No mis-fires, and no oil fouling.

 

Will you still get that wide strip of fire?

 

Hello Aldo,

Any 4 barrel carburetor acts like a two barrel as long as you do not press hard on the gas pedal. This kind of driving will give you better fuel economy but will not necessarily put a grin on your face. When you step hard on the gas the secondaries (second set of air venturis) on the carburetor open up and deliver more air/fuel and more power. This is less economical driving but delivers big smiles. The best thing to do is to keep your engine tuned and to keep your carburetor in good operating condition also. The carburetor has air/fuel adjustments that can optimize performance as well. A lot of information is available from the carburetor manufacturer's websites about rebuilding and improving carburetor performance.

I have the Goodyear Eagle GT II's on my Corvette and I do not like them. I just ordered a set of Firestine Indy 500's. The Cooper Cobra's are a good choice too.

Power loss between the flywheel and the rear wheels? - about 10 to 20% if I remember right. Closer to 10% for a manual transmission car and 20% for an automatic.

Now if you want to go for a long ride in your "Vette and try to save on gas - you can change the rear axle ratio to a 3:08 or a 2:73. These are more economical gear ratios in that they will lower the engine RPM's at highway speed.

Theother way to save on fuel will be to drive the Mini.

[sm=icon_cheers.gif]

 

Texas Jim: My 73 has a return line from the fuel pump. I thought they started doing that when they increased the thermostat temps to cut emissions to help avoid vapor lock.

Was the vent line you were talking about, the one going to the charcoal cannister?

DV8 is right on target with the hp loss although I thought the manual was more like 15%. But all cars are different.

 

73shark, I don't know when the factory went with a fuel return, it's just something I was taught to keep cooler fuel going into the carb. Yes, it's the line to the charcoal canister. You'd want to "T" off as close to the carb as possible.

DeeVee, Why don't you like the Good Year Eagle tires? The Eagles were the only lettered ones that I considered buying. There's just not a great manynew performance tires made for our wheels. All the new stuff is made for the bigger wheels.I had those Firestones (lettered Jobs) for awhile but took them off before they wore out as they rode so damn hard. I went with a half decent Good Year touring tire this time (Black wall) as it rides very smooth and does ok in the corners for how I drive. (I wanted to try the black wall for the plain look this time and I do like how it looks.) I looked into Michelins (like that new rain tire for the 'Vette) as I've had good luck with them in years past on other cars, have some on my Caddy,but they had nothing to fit.

 

Hi Texas Jim,

thanks for the nice tips about spark plugs. i will surely go for them because it's an easy job.I don't know if I'm able to do also the job on the "fuel return circuit"
unfortunately I can't go for more extensive tuning jobs on my Vette because there are no specialized mechanics in my area ( in north italy yes instead) and because the "Vette fever" is taking away time to my job : I'm a sound engineer and I manufacture speakers and amps . this is my website : www.audioanthology.com . I have only foreign countries customers and a business partner in Washington DC. This is the reason of my quite good english. in past summer I've been at my US partner's place and drove his Aston Martin DB7 450HP. then I fell in love with sport cars and decided to go for a vintage Corvette.

Usual USA roads ( from what I see in TV and personally experienced on the US east coast) are not very funny for sport cars. they are flatand too straight . In my area we have not very flat roads ( roads areoften in poor conditions)but lot of fun when driving in the hills' area ( many turns and going up-down on the hills). I'll try to find the best tuning to drive my Vette on these roads. As soon as I can drive my Vette ( still waiting for italian ID plates : it will take lot of time) I will try to make a video clip while driving on these roads , so you can have an idea

thanks for your time
Aldo