403 Olds CCC Swap Gone Wrong

[jpoole]

Hey guys, put a 403 in my HO and can't get it to run on the computer. Finally got rid of all the codes but it will not run right and is backfiring. There are a couple of things that are weird. Mild cam and high compression pistons (9.50 or so) using Edelbrock performer, AR headers, DUI distributor and SMI carb built for cam and compression etc. See attachment for cam specs.

1. Replaced MC solenoid as it was dead, however it reads 30 ohms and I read it should be 20
2. Installed heated O2 sensor however I don't appear to be getting to closed loop. It ran around 30 with 6 cyl dwell meter for a while and then dropped to 6 after it warmed up. It was not cycling up and down by 5 like it should.
3. set timing to 20ish when running with CCC disconnected, 35 to 40 when it is plugged in at 700 rpm
4. TPS set to .48 volts

Help!!!!

 

[jpoole]

Pretty please...

 

[Pontiac455]

How is the vacuum? There might not be enough for the map sensor at idle.

 

[jpoole]

I will check tomorrow. Thanks

 

[DoubleV]

What's the actual problem? It backfires through the carb or exhaust? What kind of backfiring? Does it backfire constantly or only at certain times? Does it drive at all or is the backfiring too bad to even drive it?

Also, are you certain the engine has been assembled properly? What is the ACTUAL compression ratio?

The TPS is supposed to be like .45 or so at idle. 4.8 or so is only at WOT.

 

[techg8]

2. Installed heated O2 sensor however I don't appear to be getting to closed loop. It ran around 30 with 6 cyl dwell meter for a while and then dropped to 6 after it warmed up. It was not cycling up and down by 5 like it should.
3. set timing to 20ish when running with CCC disconnected, 35 to 40 when it is plugged in at 700 rpm

2. that drop to 6 dwell when hot means youre way lean and the computer is trying hard to richen it up. Have you adjusted the idle air bleed in or backed the idle mix screws out to richen the idle mix? Think of the idle air bleed as fine adjustment, and the mix screws as coarse adjustment.
3. with green connector grounded you set 20 degrees advance at what rpm? I believe the system wants 20 to be set at like 1100rpm. from there the computer handles it once the green connector is un-grounded.

as mentioned in the other posts, more info please on
under what conditions does it backfire and out which end
vacuum readings

 

[jpoole]

What's the actual problem? It backfires through the carb or exhaust? What kind of backfiring? Does it backfire constantly or only at certain times? Does it drive at all or is the backfiring too bad to even drive it?

Also, are you certain the engine has been assembled properly? What is the ACTUAL compression ratio?

The TPS is supposed to be like .45 or so at idle. 4.8 or so is only at WOT.

1. with computer connected, it backfires through the exhaust on release of throttle when you rev it or hold some rpm in it and release throttle.
2. have not tried to drive because of backfire, but have backed it up in garage.
3. Beleive it is assembled correctly as I can drive it without CCC connected to distributor, just runs rich
4. Told "Around 9.5" by builder. Don't know exact.
5. TPS is .48 typo above and I have corrected.

Thanks, Jeff

 

[jpoole]

2. Installed heated O2 sensor however I don't appear to be getting to closed loop. It ran around 30 with 6 cyl dwell meter for a while and then dropped to 6 after it warmed up. It was not cycling up and down by 5 like it should.
3. set timing to 20ish when running with CCC disconnected, 35 to 40 when it is plugged in at 700 rpm

2. that drop to 6 dwell when hot means youre way lean and the computer is trying hard to richen it up. Have you adjusted the idle air bleed in or backed the idle mix screws out to richen the idle mix? Think of the idle air bleed as fine adjustment, and the mix screws as coarse adjustment.
3. with green connector grounded you set 20 degrees advance at what rpm? I believe the system wants 20 to be set at like 1100rpm. from there the computer handles it once the green connector is un-grounded.

as mentioned in the other posts, more info please on
under what conditions does it backfire and out which end
vacuum readings

When it was reading 6 i tried to adjust idle air bleed and mixture screws to see what it would do and it didn't move the dwell meter. 1/2 turn on all items. Tonight I will try and set timing to 20 @ 1100 rpm with distributor computer connection disconnected.

Also, my sticker for the old motor says to set timing to 20, is this the correct number as I am hearing to also try lower numbers.

 

[88hurstolds]

212/219 @ .050 is too much cam for the CCC system.
The factory grind is 196/208 @ .050 with .440/.440 lift and 109LSA if you get too much cam with the computer it will not run right.

210/216 @ .050 will need to be advanced 4 degrees to keep the computer happy in a 307, this is pretty much the limit of the CCC system.

Engle 2EP-15/18 207/216 @ .050 with .466/.496 lift is a good cam.

Crane also has H-260-2 204/216 @ .050, .454/.484 lift.

 

[jpoole]

212/219 @ .050 is too much cam for the CCC system.
The factory grind is 196/208 @ .050 with .440/.440 lift and 109LSA if you get too much cam with the computer it will not run right.

210/216 @ .050 will need to be advanced 4 degrees to keep the computer happy in a 307, this is pretty much the limit of the CCC system.

Engle 2EP-15/18 207/216 @ .050 with .466/.496 lift is a good cam.

Crane also has H-260-2 204/216 @ .050, .454/.484 lift.

Well, I spoke with a few engine builders and this is more or less what all 3 recommended for use in my 403 with the CCC system. IDK