327_TPI_77_Maro

iTrader: (8)

Hi guys, I have equipped a 1987 305 TPI long block with the 1983 LG4 CCC Qjet/computer control/all emissions crap. I just rebuilt the carb, it is a 1983 17083218 I got off a 1983 LG4 car.

Problem #1: I am getting fuel drizzling out of the passenger's side booster (only the pass side!) at idle, and I assume, at all throttle positions. It is literally streaming out with the engine running, and it will continue streaming out with the engine off for several minutes. I set the float level at 11/32" when I rebulit the carb. I just took the air horn off, verified 11/32" was correct, and actually bumped the float level down a touch to 12/32". Reassembled, no difference, car still pours fuel down the passenger side primary. The car does drive but loads up at idle, now I know why.

Problem #2. The car has good throttle response off idle and drives okay puttering around. However if you give it heavy throttle, staying on the primaries and not opening up the secondaries, the engine will cut out and die if you keep your foot in it. If you back out it will recover. I can brake torque the car and increase the throttle slowly, and when I reach the WOT on the primary side only, secondary butterflies not open yet, the engine will just die and I have to restart. Could this be related to the booster dripping fuel? This seems like a lean scenario. I have had this happen with non CCC Qjets before and never was able to fix it. Got so frustrated I would throw them out and replace w/ something else. I am about to do that with this carb!!! The MCS travel is correct. The IAB dwell is correct and car runs in closed loop. Could the fact that I set the dwell angle with the booster dripping fuel be giving me a lean condition on accel, because I have the IAB artificially lean to compensate for the O2 sensor seeing the fuel dumping at idle? If this is not the problem how do I richen up accel enrichment? I shouldn't have to widen up the MCS travel on a completely stock 305.
I hate these carbs, so, so, so much! I am not an amateur rebuilding carbs but these Qjets are the frieking worst.

327_TPI_77_Maro

iTrader: (8)

Nothing, huh? I'm going to play a fun game tomorrow. I'm going to get another lG4 junkyard carb and install it without cleaning, rebuilding, anything. I bet it works better than my meticulously clean, rebuilt Qjet. Did I mention I hate these carbs? I wouldn't be surprised if it's a warped airhorn causing my problems. I still don't understand how that would make fuel come OUT of the booster, but oh well.

five7kid

iTrader: (14)

Man, give a guy a break! I don't live here, ya know. . .

Okay, new float? If not, it could be soaked, making to too heavy to float properly.

Now, are all of the emulsion tubes in place? The ones coming from the air horn.

Warped air horn? Not good, regardless of whether or not it's causing the fuel dripping.

327_TPI_77_Maro

iTrader: (8)

The float looked okay and didn't seem heavy but I do have a spare. I'm curious why it was only dumping out the passenger's side. I've had Holleys have bad float needles before and dump tons of fuel out the boosters, but it was usually on both sides. I also have a spare base casting to try if I have to.

99Hawk120

I'd actually guess the idle and/or primary feed that ISN'T dripping has a blockage. This would cause you to have to open the throttle stop enough to get nozzle drip at idle out of the WORKING side.

Use a mirror over the primaries and watch the nozzle that isn't dripping while working the throttle. I bet you don't get much fuel out of it. It'd explain why the car dies; at idle you have too much fuel due to nozzle drip, but at wider throttle openings, a single working primary isn't cutting the mustard.

327_TPI_77_Maro

iTrader: (8)

I did what I said I'd do, I got another junkyard carb and threw it on without opening it up. Guess what, it works, no more dripping. This "new" junkyard fresh carb is from a Buick with I think a 307. I had to swap the chevy baseplate on and the electric choke, as well as reroute for the center fuel inlet but it starts sooo easy now and runs decently. Here's the current problems:

1. I can't get the dwell above 20-25 degrees. I'm guessing this carb is jetted very lean because it came off an 80s smog Buick. It had the fattest secondary rods I've ever seen, they almost didn't taper from the fat top part, and the secondary air doors were restricted to 50% opening. I'm sure the primary side is pretty lean as well. When I screw the IAB in to richen the mixture the idle speed picks up and the idle quality improves. However this makes the dwell drop to around 10 degrees. When I back the IAB out to increase the dwell the idle quality and speed get worse. Why does this car not like running where the computer wants it to? It's a frieking stock 305.

2. I still get a huge hesitation if I open the throttle very fast on the primaries. It will backfire if I stab it. If I give heavy throttle but tip in more moderately it picks up power fine. Any thoughts?

five7kid

iTrader: (14)

Give the idle mixture screws in the base a turn out each. Try the IAB adjustment again.

Get rid of the fat secondary rods. Get a lower letter hanger.

Fast355

iTrader: (2)

The 307 has the lame rods, but typically a F-Hanger. Source a pair of DR or DA rods and you will like the difference.

327_TPI_77_Maro

iTrader: (8)

I have DR rods in it now. I tried backing the idle screws out a little at a time. Not much better. I can bring them out to like 8+ turns each without much difference. I'll have to take the lid off this thing and see how it's jetted. The caprice carb I was using from an 83 LG4 previously had 75 jets in it and 50 something rods. I bet this thing is leaner. But I still don't understand why a stock as hell 305 needs to be richer. The carb I am using right now is from a 1983/84 Buick LeSabre 307

99Hawk120

Mine always had R through T hangars and DD rods. I've been through 4 now, I think. The pre 85 motors respond well to better rods.

Anyhow, don't forget to grind the stop on the air valve arm so the air valve can open all the way. Did you check the size of the idle mixture feeds?

327_TPI_77_Maro

iTrader: (8)

I have not modified the idle discharge openings because this is a totally stock 305 that I want to be emissions legal. This is a stock for stock application here. I am using the 1983 Caprice 305 LG4 baseplate so it has the discharge ports sized for exactly the application I am using.

Fast355

iTrader: (2)

My 1988 Cadillac had LAME DD rods but a decent F-hanger. I swipped the F-hanger and used it on my DR rods in my G20. When I swapped in the 403 into the Cadillac under the CCC carb, I used a set of DA rods from the GMC 403 motorhome engine and the K hanger from the G20 on a 403.

theboilermaker

What is your timing set at? That can explain some of your symptoms.

327_TPI_77_Maro

iTrader: (8)

Timing set at 6 BTDC w/ EST wire disconnected. This should be the spec for the 1983 lG4, unlike the later ones that were 0 BTDC.

naf

iTrader: (7)

Where are you now? What's the used carb doing with changes to IAB and mixture screw settings? Richening the IAB should cause the MCS to attempt to lean the carb, increasing dwell. Were you getting a ranging dwell or was the dwell changing with subtle changes in TPS?

Have you opened up your rebuilt carb to verify that the hinge pin for the float was in correctly? If the tang on the pin is not in the slot (pass side I think) it can slip and allow the float to rise. While you're at it, I'd blow out the passages and try it again. Didn't you have it running right a week or so ago?

327_TPI_77_Maro

iTrader: (8)

I "thought" I had it running right a week ago. The carb still had the fuel dribbling problem. I have the Buick 307 Qjet on the car now and it no longer dribbles, but it is insanely lean on the primary side. I am going to open it up and throw the LG4 jets/rods in there and put it back together and see what happens. I also have a 1984 trans am LG4 Qjet coming from ebay that I got for $5. Something has to work right!