Okay this is driving me crazy. I have an 87 Cutlass with a SBC vin R Vortec 350 freshly rebuilt. 9.5:1 compression, Edelbrock 2209 cam(212/222 @ .050"), edel brock 7801 chain and gears, Thunder series AVS 650 carb w/spacer,RPM air gap intake, GM HEI distributor for a 77 camaro, accel shorty plugs .040 gap, Holley blue fuel pump, Hedman shorty headers, March serpentine conv, and 700R4 Trans. It's running extremely rich, and if I step on the gas to quickly it will stumble, stall, and or backfire through the intake. When I check the plugs after running it they're black. I have set the fuel pressure anywhere from 3.5lbs to 5.5lbs. with no change. I've set the timing from 12 to 16 BTDC. The idle mixture screws can be turned all the way lean and the car will still run. I've tried hooking up the vacuum advance from the dist. to both ported and manifold vacuum with no change. I checked to make sure the correct jets, and metering rods were installed from the factory. I've tried several step up springs, and then I tried installing my friends Quick Fuel 750 Carb. No change at all. I removed the timing cover to check the position of the crank sprocket. It was not at the 0 degree setting, so I switched it to 0. No change. I don't think it's a valve lash/spring problem because every plug is black. Could it be something with the HEI distributor? Wrong one for this motor, Or some other ignition problem? Ignition module under the cap? PLEASE HELP BEFORE I BURN THIS CAR TO THE GROUND!
Extremely rich/Backfiring through intake/Stalling
- Thread starter apollina76
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SLICK79WGN said:
I tried 2 different gauges on it to make sure I didn't have a faulty gauge. I'm really leaning toward a faulty reman. distributor. Is it possible that an HEI distributor for a 77 camaro isn't compatable with this 97 vortec motor? I didn't think there was any difference. :?:
I also forgot to mention that I did adjust the float level to manufacturer spec when I had the air horn off. They were both out of spec. Also checked the needles and seats for debris as well.
HEI distributor- Install adjustable vacuum advance canister and limit to 10-12 degrees of vacuum advance.
The misfire or stumble is probably either a lean condition or late ignition timing or both. Check the accerator pump circuit and check total timing even if you have to install timing tape to your harmonic balancer. This is a nice set up, I have a similar set up in my Monte and you only need 32-34 degrees of total ignition timing. Of coarse do this with the vacuum advance plugged temporarily.
Black or sooted plugs indicate a rich condition, and I am assuming that this is just a symptom that you discovered while trying to figure out why the engine stumbled? The stumper is that you said it did the same thing even with a different carb installed. It appears that you may have more than one issue. But if you can get rid of the stumble then you can concentrate on the sooty plugs. Just my thoughts.
The misfire or stumble is probably either a lean condition or late ignition timing or both. Check the accerator pump circuit and check total timing even if you have to install timing tape to your harmonic balancer. This is a nice set up, I have a similar set up in my Monte and you only need 32-34 degrees of total ignition timing. Of coarse do this with the vacuum advance plugged temporarily.
Black or sooted plugs indicate a rich condition, and I am assuming that this is just a symptom that you discovered while trying to figure out why the engine stumbled? The stumper is that you said it did the same thing even with a different carb installed. It appears that you may have more than one issue. But if you can get rid of the stumble then you can concentrate on the sooty plugs. Just my thoughts.
just curious, did you find the problem? check your float bowl levels and seats. if they are off, sometimes it will be pouring gas out when it shouldnt be, mine did that one time, and had just a little piece of rubber from somewhere in my float seats. you may even have fuel coming out of the secondary's at idol
im having a simliar problem with my sbo 350, new hei with vacuum advance, timing around 12-14, 12inches of vacuum, holley q-jet style 650cfm, unknown cam, edelbrock performer intake, heddman headers, ect. im going to buy a BN carb and rebuild the holley while its off and see if that fixes my problem of the car falling on its face at 4700rpms, running very rich, dying out/sputtering if its not warmed up, and i get around 7-8mpg. it still runs very rich no matter on the carb fuel adj. on the carb.
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