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CROSSFIRE TO CARB.

 
buffyzoie
I love my Chevy Chevette!
Posts: 4
Joined: 12/09
Posted: 12/06/09 06:22 PM

Hello.

my friends and I swapped the old motor to a 350 with a holly 750 double pumper carb, elderbrock intake, which raised the motor. There was a problem with getting enough air to the carb. I put on a hood scoop old style ,but I had to cut a hole in the hood to make it fit. It looks cool and works very good. No sputters, start offs are great. You have to watch out because a small push on the gas makes it take off. It takes a little practice but once you get the feel. WOW watch out.
To answer your question. It is possible and worth the effort. It is a rocket. Happy birthday to all you 1984 corvette ownwes Jan 1 2010 "no emmission tests" in Ga. I say do it. It blows away the the original motor. The only differance is that you have to add a ramair intake and mold your hood.

sam  

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buffyzoie
I love my Chevy Chevette!
Posts: 4
Joined: 12/09
Posted: 12/06/09 06:24 PM

Hello.

My friends and I swapped the old motor to a 350 with a holly 750 double pumper carb, elderbrock intake, which raised the motor. There was a problem with getting enough air to the carb. I put on a hood scoop old style ,but I had to cut a hole in the hood to make it fit. It looks cool and works very good. No sputters, start offs are great. You have to watch out because a small push on the gas makes it take off. It takes a little practice but once you get the feel. WOW watch out.
To answer your question. It is possible and worth the effort. It is a rocket. Happy birthday to all you 1984 corvette owners Jan 1 2010 "no emmission tests" in Ga. I say do it. It blows away the the original motor. The only differance is that you have to add a ramair intake and mold your hood.

sam  

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buffyzoie
I love my Chevy Chevette!
Posts: 4
Joined: 12/09
Posted: 12/06/09 06:43 PM

Sorry I posted it 3 times . I am new to this site. I am a happy guy with a screaming corvette. A dream come true.
Sam  

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RayRay400
I love my Chevy Chevette!
Posts: 7
Joined: 11/10
Posted: 11/23/10 04:06 AM

i am interested in learning more about the lock up switch for the torque converter?  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/23/10 05:03 AM

Icon QuoteRayRay400:
i am interested in learning more about the lock up switch for the torque converter?

If you still have the original TCC wiring in the car then all you need to do is run the tan/ blk wire ( that used to go to the computer ) to ground through a switch
When circuit grounded at switch convertor is locked ; will still unlock when you  brake
Still have to remember to disengage TCC when coming to a stop or engine may stall as soon as you take foot off brake


TCC



You can also put a internal switch in the trans that will lock convertor when ever trans goes in O/d so no switch needed  

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RayRay400
I love my Chevy Chevette!
Posts: 7
Joined: 11/10
Posted: 11/23/10 05:39 AM

do you have to manually engage the TCC switch.  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/23/10 02:26 PM

Icon QuoteRayRay400:
do you have to manually engage the TCC switch.

Yes
because the computer used to do it and it is gone with the carb conversion

If you want it to engage automatically you need the 4th gear switch in trans as I noted above  

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RayRay400
I love my Chevy Chevette!
Posts: 7
Joined: 11/10
Posted: 11/24/10 01:29 PM

does the trans have to be removed to install the switch?  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/24/10 02:48 PM

Icon QuoteRayRay400:
does the trans have to be removed to install the switch?

Switch is in the valve body so only the pan needs dropping  

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RayRay400
I love my Chevy Chevette!
Posts: 7
Joined: 11/10
Posted: 11/25/10 05:46 AM

wow, you know your stuff!
where can the switched be purchased? have you intalled 1 before?  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/25/10 04:10 PM

Icon QuoteRayRay400:
wow, you know your stuff!
where can the switched be purchased? have you intalled 1 before?


If you look at the diagram I posted above  you will see that all that is required is the tan/ blk wire from the solenoid run to the 4th gear switch inside the trans.

Recall stock T700 4th gear switch ( now unused with no computer ) goes open in 4th; would need to be changed to one that closes in 4th gear.

Some good reading here on options
http://purplesagetradingpost.com/sumner/techinfo/700R4p1.html  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/25/10 04:11 PM

Icon QuoteRayRay400:
does the trans have to be removed to install the switch?

4th gear switch shown wired for auto TCC operation



4Thgearswitch  

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84Cali-Shark
I love my Chevy Chevette!
Posts: 1
Joined: 07/11
Posted: 07/28/11 11:06 PM

Hey I Have An 84 That Runs Pretty Strong, But im Looking to run headers and switch to Carbs..what kind of set up do you recommend with a holley 4 barrel Carb?  Grin


 Vince  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 07/29/11 06:48 AM

there have been a LOT of other people who have swapped to a carb from the crossfire...

which one to run?????  

you will need to carefully select the intake manifold... as there have been problems with no place for the air filter..

look for a low profile intake...  there are height measurements available in the catalogs measured from the back of the top of the block to the carb mounting flange..  to calculate height needs..

there are some LOW profile air cleaners...

you will also need to convert to a conventional vacuum advance HEI distributer..  as you are going to loose the electronic timing control...

please pay close attention to the needs of the throttle valve cable attachment point on the throttle lever..  depending on the carb.. you may have to purchase an additional bracket to have the correct distance from the centerline of the throttle shaft..    failure to get this right..  and the adjustment will cost you  a transmission within a block or two on the first trip out the driveway..


you will also need a return style fuel pressure regulator to reduce the 25 pounds or so of pressure the intank pump can create  down to 4 or 5 pounds the carb will accept without flooding...  why.. the electric fuel pumps on these cars do not have a bypass..  conventional NON bypass pressure regulators will cause the in tank pump to burn out..  you do have a choice of installing a low pressure.. 4 or 5 PSI fuel pump in the tank..  but you are better off with a return style pressure regulator as this will provide enough flow and volume for almost any operating range..

you will also need to rewire the fuel pump relay...   so the fuel pump relay gets powered when you crank the engine...   there may or may not be a oil pressure switch with 3 terminals on your car..  or a single wire oil pressure switch with a second oil pressure switch with 2 wires on it that powers the electric fuel pump when the oil pressure is up .. this is done on the later C4 cars.. starting in 85 with the TPI...  

you will also need to install a torque converter lock up kit... as the ECM controls the Torque converter lock up...  there are kits available to do this..

the 84 models only have a cooling fan switch in the right cylinder head to control the radiator cooling fan...  be sure that you install a new one.. and a new pigtail to properly connect it.. so you don't melt the motor.. the cooling fan switch is designed to work with a 192F thermostat  a 13 pound radiator cap... and 70 % coolant to 30% water cooling system mix..

~~~~~~~~~~~
the cam and heads combo needs to looked at for increased performance..

these mods.. will also prevent the car from being sold to a person who lives in an area that needs to be smog tested...


if you plan on increasing horsepower..  you might want to think about a transmission up grade also...  


if you just want headers....  and can leave the crossfire alone...

you can select a pair that has ports for the air injection system to function properly.. and places for the oxygen sensors..

the computer runs checks on the air injection system function by turning it on and looking at the oxygen sensors for the response.....

the computer also sets fuel ratio with oxygen sensor data while in closed loop...  

the corvette exhaust manifolds are not that restrictive... for the normal operational RPMs of the crossfire engines... since they rarely see the upper side of 4500 rpms..  and cruise is between 1800 and 2200 rpms..


additional...   there have been people who have improved the crossfire performance by opening up the intake passages as the factory blocked some of them slightly..  to even out the air flow..    these people have also enlarged the TBI bores and installed larger throttle blades..  and more pounds per hour TBI fuel injectors.

just swapping in a 383 motor and keeping the same Crossfire unit will greatly improve your cars ability...

i know.. as i have worked on a few crossfire 383 motored cars... i don't know what cam was selected... talking to a cam grinder would be the best thing..

paying attention to the various sensors and pigtails that they are not melted and making proper contact...  remember. these 84 models are 28 years old..   and up grading to the newer style engine coolant temp sensor and pig tail is cheep.. under 20 bucks at most autozones..   part number SU102...

Su102  

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helldog
I love my Chevy Chevette!
Posts: 1
Joined: 11/11
Posted: 11/08/11 11:51 PM

I just finished changing my 86 Corvette from a tpi to a carb, Not a hard deal to do, The big problem is the clearance at the closing of the hood, I used a old alum intake from a old junk yard camaro and a Quadrajet carb , it gave me 3-4inch hood clearance no problem with the hood , the other hurdle was the fuel delivery, I installed a 4-6 lb. pump at the rear of the car behind the licence plate and wired it to the existing wires , elimating the return line I left all the stock wiring and let the computer as it was to run everything , the results are great the car runs better than ever and i dont have to worry about breaking down all the time.  

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