I have a 87 305 4brl iroc and someone told me that my carb has a computer. Is that true,if it is and i switch to a bigger engin what upgrades should i have to do????

 

If your carb has a blue 2 wire electrical connector up top on the front-left corner and a 3 wire connector on the right near the pumper, you've got a compucarb. You could make it work on, say, a 350 if you jet it up a little, then it's just a matter of dialing it in. If you use the compucarb on a new engine, you'll need to put your existing electronic distributor on the new engine or your ECM will keep throwing code 12 at you.

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DR Stevens
Car #1: my ride
1984 TransAm
305HO(L69) 95K & counting
750 cfm Q-Jet reman. by Holley
K&N filter
700R4/Superior shift-kit
3.42 rear/3.73 blew up!!
underdrive pulleys
Accel HEI Super-Coil
180 stat/hi flow water
pump/Jet fan switch
dual snorkel /w/ hood louver
3" exhaust of some sort
partial emissions delete
Stock-appearing radio /w/
10-disc changer
Car #2: My wife's ride
1991 Firebird/Formula
305TBI(LO3) 99K & smoking
K&N air filter
Hypertech Thermomaster Chip
more engine mods later
400W amp /w/ 12" sub

 

I was thinking of going to a 400sbc should i get a new carb a remove the computer devices?

 

I think that's what the general consensus of the 400 guys have done, I don't know if anyone has ever used a comp.reference carb on anything bigger than a 350. That's what i'd probably do, to minimize tuning troubles.

If you go this way, you won't be using your existing carb & distributor. If your transmission has lockup, you'll need a manual control for it.
Your EGR solenoid, smog pump valves, vacuum sensor, coolant sensor for open/closed loop, baro sensor, and speed sensor will all become non-funtional without the computer. You'll lose your cruise control without the speed sensor. You won't need the knock sensor, or any other computer-related emissions sensors.

------------------
DR Stevens
Car #1: my ride
1984 TransAm
305HO(L69) 95K & counting
750 cfm Q-Jet reman. by Holley
K&N filter
700R4/Superior shift-kit
3.42 rear/3.73 blew up!!
underdrive pulleys
Accel HEI Super-Coil
180 stat/hi flow water
pump/Jet fan switch
dual snorkel /w/ hood louver
3" exhaust of some sort
partial emissions delete
Stock-appearing radio /w/
10-disc changer
Car #2: My wife's ride
1991 Firebird/Formula
305TBI(LO3) 99K & smoking
K&N air filter
Hypertech Thermomaster Chip
more engine mods later
400W amp /w/ 12" sub

 

BIG THANKS eightTfourTA

 

Before your rip off the computer, you might want to check with your local emission laws. Also, you really don't have to rip off your computer to drop in a 400, Gulstrand did it in an 83 firebird they used for suspension testing. Gulstrand engineering manufactures suspension components for gm products. They kept the computer, with no problems.

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86 SC, 305 LG4, TH700R4, SLP headers, 3" cat and exhaust. Mild cam 204/214, .423/.442. SLP shift kit, richmond 3.73's w/limited slip. Susension Technique Sway Bars, Globel West Wonderbar, Poly everything bushings, Metco LCA's, Lakewood Panhad Rod. 16" ROH, with Toyo 245's. For autocross, 16" IROC's w/bfg R1's... Need more speed.....

 

Ah yes, gotta ask 'the man' first, sorry I forget, 'cause I don't have to worry about that here in FL!!!

 

What did they do to the carb to make it work on that engine? Did they change jets, or just tune it differently?
Also, I thought that a larger displacement engine would need a greater spark curve than the computerized distributor could provide. I dunno, maybe i'm smoking some bad Marlboro's.