Question about 403 swap

[86cutlassrules]

Im switching a 403 into its either an 86 or 87 cutlass Supreme Brougham, and wanted to know if it is possible to keep the distributor and carb. My friend a few years ago went to a 400 Chevy from a 305 in his 87 Monte SS and kept everything, the only thing he did was rebuild and rejet the carb. But I saw on this post http://gbodyforum.com/viewtopic.php?t=7414 that everyone is saying hes not using the comp. I like the idea of using the o2 sensor to keep things relatively tuned, not to mention keeping the lock up on my trans. It will be my dads daily driver and built fairly mild. I have the car hidden at a friends house right now because its a Christmas suprise so I cant check anything on it right away, which is why I cant remember the year. Does the 307 have a knock sensor in it for the timing? Thats the only reason I could see this not working.

 

[Uncletruck]

You can use the CCC carb and distributor with the 403, but with two major disadvantages. The carb and distributor are not calibrated for the 403, and thus won't likely work very well. Second, the CCC carb is about the most lackluster thing you can get as far as performance, they are nothing but overly complex pieces of emissions restricting garbage IMHO. It's a waste trying to use it on the 403 as it will diminish the performance advantages to swapping to the 403 in the first place.

-UT-

 

[86cutlassrules]

Other then the fact that it automatically adjusts the mixture whats so different from setting it up like any other Q-Jet. With proper jets and rods and maybe changing idle restrictors why wouldn't it perform well? Couldn't I also just recurve the distributor for performance like any other HEI and then allow the computer to do the fine tuning work on both the carb and distributor? I'm not running a massive overlap or anything on the cam so I shouldn't really get raw fuel or anything by the O2 sensor to make it act up.

 

[Uncletruck]

All you have to do is pull the air horn from one of those carbs to see what I mean. Not too many people were successful at just rebuilding them with stock components and getting them to work right again, none the less trying to make one perform better. I imagine any attempts at changing the jetting or rods would be a lost cause. The computer and O2 sensor is calibrated for the 307 also, and you are looking at an engine with almost 100 CI of additional displacement. There was never a CCC module made for the 403, it was discontinued before the time of CCC. If you are adventurous you could probably make the whole thing work with a lot of experimenting and patience. To get the whole CCC thing to work, you'll need to use the 307 EGR setup also, which has sensors that are in the intake manifold, and if your 307 had an AIR system, you'll need it too. If you stick with the stock, simple non computer 403 carb/distributor and use a catalytic converter, you won't have pukey-rich exhaust or anything like that if its tuned up right, and it's going to work a lot better without the worries. Kinda the KISS thing going on here.

-UT-

 

[86cutlassrules]

Ok, I totally understand what you mean now. So no matter what happens the carb is going to try and be lean for a 307, even if the o2 sees that its not a stoichiometricly correct mixture. I was hoping to have basically a budget fuel injection where the o2 would see that the air fuel ratio wasnt at 14:1 and it would tweak the mix back and forth to compensate for plug wear, outside temp, and all the other variables. Considering he runs in and out of NY all the time I was also hoping for optimum fuel millage while still getting the monster torque of the 403 so the car just felt quick unlike with a 307 and maybe pull 13 or 14 city. Looks like the 403 is keepin its carb and HEI.

 

[dougfather]

To get the whole CCC thing to work, you'll need to use the 307 EGR setup also, which has sensors that are in the intake manifold, and if your 307 had an AIR system, you'll need it too. If you stick with the stock, simple non computer 403 carb/distributor and use a catalytic converter, you won't have pukey-rich exhaust or anything like that if its tuned up right, and it's going to work a lot better without the worries. Kinda the KISS thing going on here.

-UT-

Pre-85 Olds heads are not interchangable with 85(1/2) to 90 Olds factory intake. They made a head and intake change in 85 (all or part of that year), so it won't work with earlier heads. This link tells all about this:

http://www.robertpowersmotorsports.com/G-bodyV6-V8.html

 

[joe_padavano]

I'll disagree about the adaptability of the CCC Qjet. The computer only controls the primary side. The secondaries use the same metering rods as any other Qjet. You can easily swap these and change the air valve wrap. The one thing you do need to change is the air valve opening angle. The 307 carbs have a stop that limits travel to 70 deg. A little filing lets it open the full 90 degrees. The one drawback to the CCC system is the fixed advance curve on the distributor. You need to burn a new PROM to fix that. This had been done by several others.

On a side note, when the factory adjustment process is followed, it is very easy to get the CCC system to function just fine. My 86 has run perfectly for two years after carb rebuild and adjustment. The problems people have is that the system is very sensitive to vacuum leaks and failures in sensors. You need to follow the checkout procedure in the Chassis Service Manual in the exact order listed.

 

[86cutlassrules]

Im glad to hear that it is do able, however couldnt I swap the egr from the 307 intake to the 403 stock or maybe a edelbrock performer? What other sensors have to be swapped over? Are any of them specific to the intake manifold? or should they fit on just about any intake?

 

[joe_padavano]

Im glad to hear that it is do able, however couldnt I swap the egr from the 307 intake to the 403 stock or maybe a edelbrock performer? What other sensors have to be swapped over? Are any of them specific to the intake manifold? or should they fit on just about any intake?

The EGR valve is controlled by a computer-operated solenoid vacuum valve. You need to swap the valve package (the black plastic box at the rear driver's side corner of the intake) in addition to the valve itself. Of course, the EGR is an open-loop function. The computer issues a command (turns the solenoid valve off or on) but has no feedback as to whether the EGR actually works or not. Newer cars have position feedback on the EGR valve itself, but the 307 does not. As a result, you can use or not use the EGR, your choice, and it won't affect the computer (nor set a code) either way.

The only sensor that mounts directly to the intake is the coolant temp sensor. It is located in the coolant crossover at the front driver's side of the intake manifold. There are two coolant sensors. The one closest to the thermostat housing is the one that operates the idiot light or gauge. The outboard sensor is the one that operates the computer.

The MAP sensor mounts to the inner fender and is operated with a vacuum hose to the intake. There is also a BARO sensor under the dash. The TPS is built into the carb. RPM sensing comes from the distributor. Late 307s (1990 and maybe 1989) have a knock sensor, but earlier ones do not.

 

[Uncletruck]

Here is some good info:

http://www.robertpowersmotorsports.com/CCC.html

Try two things. First, running the 403 with the original style carb and distributor. Then, switch it all to a CCC system. See which one runs and drives better and which is easier to work on. :wink:

-UT-