installing 350 tbi into carb car.
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Junior Member
Joined: Apr 2008
Posts: 56
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From: Michigan
Car: 1985 Trans Am
Engine: built 355
Transmission: th350
Axle/Gears: Borg warner 3.08's
installing 350 tbi into carb car.
Im buying a 93 tbi motor and i was wondering if i can install it in my 85 trans am with a carb. What would i have to do to make the tbi work? Im takeing the engine out of a van everything is still whole so i can take what i need to make the tbi work. I have a 750cfm edelbrock carb will that work or is it to big for the stock 350.
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Patience, Grasshopper. Some of us go to church on Sunday mornings. . . 
Any particular reason for wanting to go TBI? You said the car has a carb, are you talking a factory carb, or the Edelbrock you mentioned?
Which engine did the car originally have (assuming it was a factory carb car), LG4 of L69?
I don't know the specifics of taking a van TBI system and putting it into a 3rd gen. I would imagine you'll run up against some issues such as VSS ('85 will be on the back of the speedometer, '93 on the transmission), harness lengths and routing, connector size differences (such as the pass-through from engine compartment to passenger compartment), ECM to dash differences. If the car originally had an LG4, it most likely doesn't have the in-tank electric fuel pump provisions, such as wiring, relays, and the pick-up itself in the tank. You could do an in-line aftermarket pump, but they ain't cheap.
If you still have the factory carb set-up, that would be a fairly simple job to install it on the 350 longblock. Using the Edelbrock would be a desperation measure in my mind.
Any particular reason for wanting to go TBI? You said the car has a carb, are you talking a factory carb, or the Edelbrock you mentioned?
Which engine did the car originally have (assuming it was a factory carb car), LG4 of L69?
I don't know the specifics of taking a van TBI system and putting it into a 3rd gen. I would imagine you'll run up against some issues such as VSS ('85 will be on the back of the speedometer, '93 on the transmission), harness lengths and routing, connector size differences (such as the pass-through from engine compartment to passenger compartment), ECM to dash differences. If the car originally had an LG4, it most likely doesn't have the in-tank electric fuel pump provisions, such as wiring, relays, and the pick-up itself in the tank. You could do an in-line aftermarket pump, but they ain't cheap.
If you still have the factory carb set-up, that would be a fairly simple job to install it on the 350 longblock. Using the Edelbrock would be a desperation measure in my mind.
Thread Starter
Junior Member
Joined: Apr 2008
Posts: 56
Likes: 0
From: Michigan
Car: 1985 Trans Am
Engine: built 355
Transmission: th350
Axle/Gears: Borg warner 3.08's
Re: installing 350 tbi into carb car.
I have no idea what engine is in my car. The qjet is messing up again and i bought a 750cfm edelbrock off a buddy for $150. Im also getting a good deal on the 350 engine $200 thats why im doing the swap. What will i have to do to get the edelbrock to work jet it down? i was going to get an intake for it. How much how more hp will the 350 have then the 305?
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Well, I can't help myself, I've got to stick up for the q-jet. It can't possibly cost more to fix whatever is wrong with it (something tells me it isn't the carb itself) than it would to get that Edelbrock running. And, the q-jet will be the better carb, regardless.
To run the Edelbrock, you'd need a different intake manifold, one with a square bore bolt pattern (or at least both square bore and spread bore), like the Edelbrock Performer. You'll need a distributor with vacuum and mechanical advance. You'll need a "geometry corrector bracket" that attaches to the throttle arm for the TV cable. You'll need to rig up some means of locking up the torque converter clutch (discussed all the time - do a search). Whether you need to jet up, down, or leave it alone is a matter of tuning after you get it running. Regardless, you won't get any better performance than you would out of a properly operating q-jet, and mileage and/or driveability will be worse.
One thing not yet mentioned is the later engine has a different bolt angle for the center two intake manifold mount bolts on each side than the '85. The '85 is what the typical aftermarket intake will be. But, the Performer is available in the '87-up bolt angle style. Not a bad idea whether you go with the Edelbrock carb or stick with the stock q-jet.
To run the Edelbrock, you'd need a different intake manifold, one with a square bore bolt pattern (or at least both square bore and spread bore), like the Edelbrock Performer. You'll need a distributor with vacuum and mechanical advance. You'll need a "geometry corrector bracket" that attaches to the throttle arm for the TV cable. You'll need to rig up some means of locking up the torque converter clutch (discussed all the time - do a search). Whether you need to jet up, down, or leave it alone is a matter of tuning after you get it running. Regardless, you won't get any better performance than you would out of a properly operating q-jet, and mileage and/or driveability will be worse.
One thing not yet mentioned is the later engine has a different bolt angle for the center two intake manifold mount bolts on each side than the '85. The '85 is what the typical aftermarket intake will be. But, the Performer is available in the '87-up bolt angle style. Not a bad idea whether you go with the Edelbrock carb or stick with the stock q-jet.
On Probation
Joined: Oct 2008
Posts: 6,319
Likes: 19
From: Northern Utah
Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: installing 350 tbi into carb car.
Hi. I am new to the forum, but I've done what you propose. Edelbrock makes a performer EGR that fits those '93 heads, but those heads are a disaster. You can change cams all you want and necer see much more than the stock 210 hp @ 4000 rpm. But if that works for you.. You can put the Vortec heads on your short block, and GM Performance Parts offers both TBI and an EGR-provision Performer-equivalent intake, though both are pricey. But that's more combo than swap. Still, I guessed you were swapping up for performance, and not everyone knows about those no-flowing swirl-port heads.
Thread Starter
Junior Member
Joined: Apr 2008
Posts: 56
Likes: 0
From: Michigan
Car: 1985 Trans Am
Engine: built 355
Transmission: th350
Axle/Gears: Borg warner 3.08's
Re: installing 350 tbi into carb car.
Well, I can't help myself, I've got to stick up for the q-jet. It can't possibly cost more to fix whatever is wrong with it (something tells me it isn't the carb itself) than it would to get that Edelbrock running. And, the q-jet will be the better carb, regardless.
To run the Edelbrock, you'd need a different intake manifold, one with a square bore bolt pattern (or at least both square bore and spread bore), like the Edelbrock Performer. You'll need a distributor with vacuum and mechanical advance. You'll need a "geometry corrector bracket" that attaches to the throttle arm for the TV cable. You'll need to rig up some means of locking up the torque converter clutch (discussed all the time - do a search). Whether you need to jet up, down, or leave it alone is a matter of tuning after you get it running. Regardless, you won't get any better performance than you would out of a properly operating q-jet, and mileage and/or driveability will be worse.
One thing not yet mentioned is the later engine has a different bolt angle for the center two intake manifold mount bolts on each side than the '85. The '85 is what the typical aftermarket intake will be. But, the Performer is available in the '87-up bolt angle style. Not a bad idea whether you go with the Edelbrock carb or stick with the stock q-jet.
To run the Edelbrock, you'd need a different intake manifold, one with a square bore bolt pattern (or at least both square bore and spread bore), like the Edelbrock Performer. You'll need a distributor with vacuum and mechanical advance. You'll need a "geometry corrector bracket" that attaches to the throttle arm for the TV cable. You'll need to rig up some means of locking up the torque converter clutch (discussed all the time - do a search). Whether you need to jet up, down, or leave it alone is a matter of tuning after you get it running. Regardless, you won't get any better performance than you would out of a properly operating q-jet, and mileage and/or driveability will be worse.
One thing not yet mentioned is the later engine has a different bolt angle for the center two intake manifold mount bolts on each side than the '85. The '85 is what the typical aftermarket intake will be. But, the Performer is available in the '87-up bolt angle style. Not a bad idea whether you go with the Edelbrock carb or stick with the stock q-jet.
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theshackle
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Mar 5, 2017 06:37 PM
350, car, carb, carbed, carburated, carburetor, chevy, edelbrock, engine, install, installing, motor, perfrormer, spread, square, tbi
