Topic: Performace Questions
in Forum: C3 Engines
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Well guys I am getting to that point I really want to figure out what exactly I am going to do to my motor and I am looking for some advice on a couple of things.. Right now I am looking at uprgrading the ignition and putting a new higher output distributor, Putting a new cam in preferably something with a strong lumpy idle and that will give me good low- mid RPM performance, Also planning on changing lifters and springs to match the cam, set of roller rockers, and then a thinner head gasket for now to up the conmpression a little bit. Next I plan on changing out the intake for something to help out my low end and give me some more torque. But my big question is is what to do about my carb situation. The Quadrajet that is on there now is missing a lot of the linkage for the secondaries and the choke and needs rebuilt cause its just dumping a large amount of fuel through the motor while running... So I am starting to think its going to cost me mroe to get it rebuilt and replace all the missing stuff when I can just buy new...Now I buy new I am planning on going with something with electric choke but I am not sure how many CFM to get. If you guys can give me some recomendations on parts I have mentioned and what works good for you I would appreciate it
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I have Holley Street Avengers on the 69 Camaro and the 69 Vette. No problems with either carb. I have friends who run Edelbrock carbs on their hot rods and they swear by them too. So it is just a matter of preference. I don't run a stock carb because my 69 is NCRS (Not Correctly Restored Stingray).
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
There's a lot of hype regarding distributors and coils. Your stock coil will do all you want unless you plan on racing. The coil will produce as much voltage as necessary to jump the gap in the spark plugs...up to the maximum capability of the coil. An aftermarket coil may have a higher voltage rating, but it will still only produce the voltage required just like a stock coil. If you keep your car at peak state of tune, the stock system will do all that's required. Changing the advance weights and springs would be a much cheaper and more effective way of showing a performance gain.
The Q-Jet is as good a street carb as you'll find. If you feel you will be ahead of the game by changing carbs, I think the Edelbrock carbs are preferable for a street car with an excellent compromise between performance and economy...the 1406 600 cfm with electric choke or Edelbrock 650 AVS with electric choke is what you need for a 350. Holley also makes a spread bore carb that is a direct replacement for the Q-Jet as far as fuel inlet, linkages, etc.
Before you start buying and replacing parts, determine what you really want out of your car and come up with a plan to improve your engine as a complete matched system...not simply a bunch of new parts that may not be matched to one another. Many cam specialists will tell you to decide what camshaft you think you need and then go one milder in specs. Many go too aggressive in cam selection and end up not as happy as they should be.
The Q-Jet is as good a street carb as you'll find. If you feel you will be ahead of the game by changing carbs, I think the Edelbrock carbs are preferable for a street car with an excellent compromise between performance and economy...the 1406 600 cfm with electric choke or Edelbrock 650 AVS with electric choke is what you need for a 350. Holley also makes a spread bore carb that is a direct replacement for the Q-Jet as far as fuel inlet, linkages, etc.
Before you start buying and replacing parts, determine what you really want out of your car and come up with a plan to improve your engine as a complete matched system...not simply a bunch of new parts that may not be matched to one another. Many cam specialists will tell you to decide what camshaft you think you need and then go one milder in specs. Many go too aggressive in cam selection and end up not as happy as they should be.
Hmm I will have to look into the distributor situation more then I thought now..
I have been looking at the carb/intake packages from summit and I like them and all but all the carbs are manual choke. Does that mean I have to run a cable inside the car. Sorry guys all my carb experience is on quads..
Gunslinger.. I go to school not far away from you in Keyser WV at Potomac State... I may have to try and meet up with you sometime and check out your 71 if you go to any shows around the area
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
Contact Summit Racing and see if they will make comparable deals on electric choke equipped combinations. If not, Edelbrock makes a electric choke to add on, but you would probably be better off simply buying the intake you want and the electric choke carb seperately.
Dante...anytime you want you're welcome to come by. I'll be out of town the last week of the month so that's out, but most any other time would be great.
Dante...anytime you want you're welcome to come by. I'll be out of town the last week of the month so that's out, but most any other time would be great.
IF ANYTHING, CONSIDER UPGRADING YOUR STOCK DIST WITH A PERTONIX ELECTRONIC IGNITION KIT. YOU CAN ELIMINATE THE POINTS THAT WAY AND IN MAY COST ABOUT $100.00. I CHOSE EDELBROCK PERFORMER SERIES CARB. I DON`T HAVE A CHOKE AT ALL. STARTS RIGHT UP WITH A COUPLE OF PUMPS OF THE ACCELERATOR . JUST KEEP ITHE RPM UP FOR A MINUTE OR SO.
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The Woodlands, TX - USA
Joined: 1/27/2006
Posts: 67
Vette(s): 1969 Coupe, Red, L88 Tribute
Dante,
How many miles are on your motor? Don't go too wild on the top end of the motor if the bottom end is not up to it. Your '75 only has 8.5 to compression. Even if you use a thinner head gasket, your not going to increase the compression very much. So keep this in mind while selecting a cam shaft. If you go with too much cam, it will hurt low end torque.
The Edelbrock performer or performer rpm with a 1406 Edelbrock carb (600 cfm) or a Holley 750 vacuum secondary work great on small block chevys. Also, a good set of headers and free flowing exhaust will wake up your vette. Going to 64 cc heads from 76 cc heads will increase your compression and increase torque. I put a set of Vortec heads on my '76 along with other upgrades. It was one of my best investments along with a new distributor. If you have alot of miles, installing a new HEI distributor is not a bad idea. Don't go overboard on high output coils and boxes with a street motor. Spend the money on a good K&N air filter.
Just a few thoughts.
Steve
SMSCORVETTE


Its has 53,000 miles on it and supposedly all the seals and tolerances have been checked in the last 1000 miles, but when I do the rest of the motor work we plan on tearing it down and checking everything else out for ourselves. And I do realize that the thinner gasket won't raise the compression too much but I do plan on changing the heads but thats going to be a little farther down the road.. Right now the car already has a set of side pipes on it and I plan on putting a set of block hugger headers on it
Really right now I am trying to get some imput from a bunch of people before I draw up my final plans of what i am doing.. Then I am having a friend of the family that has a few pro street cars take it to his friend that owns a large speed shop in the Pittsburgh area and see if he approves of the combo I picked out and if anything else is needed
Former Member
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The Woodlands, TX - USA
Joined: 1/27/2006
Posts: 67
Vette(s): 1969 Coupe, Red, L88 Tribute
Good luck with your re-build! There are so many choices when it comes to building a small block chevy. You will get plenty of good advise from this site. Just to let you know, when I installed the Vortec heads on my '76, I could not re-install my distributor shielding, due to the different intake bolt pattern.
Steve
SMSCORVETTE


in Forum: C3 Engines
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