OK, this is my first carb'ed car so this kind of stuff is new to me.

The other day, when I'm in bumper-to-bumper traffic the van in front of me takes off and I slam on the gas to keep pace (Maybe 3/4 throttle, NOT full throttle) and my rev's go up a bit(Like 100RPM's or so) and I feel/hear the engine bog, stumple, then stall. I started it up again, except stupid me stepped on the gas hard again (HUGE line behind me) and it stalled again.

For the next couple minutes, any time I had to go forward in traffic I had to really baby the throttle. As I did this I could feel it bogging, but it didn't stall. I just went REALLY slow until the rev's got up to 1200 or so, then I could step on it. This seems to only happen for about 5-10 minutes after I start it. After that, it goes away. It doesn't happen every time either. It's very off and on problem.

I asked my dad and he told me "...that's the way carburetored cars are, live with it...". However, I told a good friend this, who is also very mechanically-inclined like my dad, and he told me that it shouldn't do that AT ALL and that a good shop would be able to tune it for me. He recommended a race shop of his friends.

But before I take it there, I wanted to ask you guys with carb's, do you have to live with this sort of stuff? To me, this doesn't seem very "streetable" if I'm stalling in rush hour traffic. Days like that, and I really start to miss my Talon and almost makes me want to pull my Laser out of storage early...


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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

What kind of carb are we talking about here?
Since you have an 87 I assume the FI was ripped off and replaced with a carb so were going to need some more info. But by chance if someone botherd hack a CCC in there you should be getting a check engine light, so if this is the case pull the codes and lets see whats going on.
SSC

 

No you don't have to put up with that in traffic. I have a CC-Quadrajet in my car and it runs much better than my buddie's TPI Camaro. It sounds like your carb's secondarys are not in tune with your headers (running too lean).

You need new metering rods try what Damon on this board suggests "DR and G hanger." You may also need a new fuel pump and fuel filter. If your car has everything else in tune i.e. spark etc, the above is all it could be.

I almost forgot to mention, you have a small supplemental intank electric fuel pump. It is to prevent VAPOR LOCK with 1987 carbed Lg4 f-bodys. If you don't hear a buzzing after your engine is on and oil pressure up, you may have a blown fuse or the pump in the tank is bad. So actually your car has 2 fuel pumps.

[This message has been edited by EDDIETA_ZZ3 (edited September 09, 2001).]

 

SSC - Nope, mines a completely stock carb'ed car. I know all the previous owners and none of them changed it to carb.

Eddie - I'm going out for a drive right away to test this bogging again. It seems to only do it when it's cold, so would that eliminate the fuel pumps? Fuel filter was changed recently, so it's not that.

The car must be tuned right, because with _0_ emissions equipment, my car still passed emissions tests about 3 weeks ago.


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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

Ok Trevor, but since you added the Headman Headers, Y-pipe, and dynomax exhaust, your car is running way leaner than it did with the stock exhaust. Now since you had an emission's test three weeks ago, I bet it is running even more leaner. They probably set your idle mixture screws way lean. Cold engines still need a richer fuel mixture. Maybe your choke needs to be adjusted?

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87 Trans Am ZZ3 crate, Quadrajunk carb DR RODS E hanger, 3.42 gears & SLP torsen diff, aluminum rear drums, aluminum bumper brace, 1LE driveshaft, stall convertor, 700R-4 downshift delay, No Air or heater junk, All go no show.

 

I've been told it might have something to do with my choke letting off too soon.

I did some testing tonight, and here is what happens exactly. I start my car, my fast idle kicks in. I put it into gear (Warm up maybe 10-15 seconds) and drive away. It then idles at just above 500RPM in drive, and will bog when the gas is pressed.

Once it is fully warmed up, it idles at 750RPM and does NOT bog at all. It runs really smooth.

Any other ideas on what it could be with this new information?

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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

Your dad was more right than your mechanic friend. To a great extent that is how carbs behave when the engine is cold. More accurately, when the intake manifold is cold, which can be well after the coolant temp has come up.

Fatten up the secondaries with a set of "DR" rods and a "G" hanger and this tendency will be somewhat reduced, but WOT on a cold intake will almost always cause a bog-then-go situation.

Also, when Rochester QJet carbs get old the little rubber cup that is part of the accelerator pump system gets "hardened" and won't seal well against the bore it sits in. It won't seal up, and you get no accelerator pump action. The car "falls on it's nose" when you get on it. Once the engine and carb warm up the rubber becomes a little softer and seals up again. The problem goes away. An accelerator pump cup is a common rebuild kit item.

 

I completely agree with Damon's statement. Before I had the LG4 removed, I used to bog all around town when I was driving early in the morning after starting up. Very embarrassing. Basically, anytime you cold start the engine and then floor it, you're going to bog hard and then go (if your lucky). It really is just the nature of the beast. My 350 does it too, with the Holley, well, sometimes

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1984 Trans Am, Goodwrench 350, TES Headers, Performer RPM Intake, Flowmaster 80 Series, Holley 600 cfm & vacuum advance, and T5 with short shift

 

Would I be able to buy the "Accelerator Pump Cup" by itself or would I need to buy an entire kit? Any idea on cost of the kit if I need?

Also, I'm assuming that by "fattening up the secondaries" I'm making it run richer?

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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

Damon - I read the article listing the part numbers for the rods. If I go to a GM dealership will they be able to figure out what part number a "G" hanger would be?

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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

You won't be able to get a G hanger from a dealer anymore, the only one they stock is a K. Edelbrock has them for their Qjets though.

 

So how could I get a G hanger then? Special order from Edelbrock or how could I get one for my QuadraJet? Or will it not work with my stock QuadraJet?


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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

Edelbrock's P/N for the G hanger is 1961, costs about $6. You can probably order one from JB's Power Centre up there, or I can pick one up for you from Mopac.

 

OK, dumb question here, but the Edelbrock parts will fit in my QuadraJet even though it's not an Edelbrock?

Also, do you have any idea what the part number is for Edelbrock DR rods? Might as well save myself a trip and get it all at JB's if I can...


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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

Edelbrock makes 2 series of carbs. Their original Performer series are copies of the Carter AFB, and their Performer Q-jets are copies of Rochester Quadrajets. Parts for a Performer Q-jet will fit your Quadrajet.

Unfortunately Edelbrock doesn't make a DR rod, they only have CC, CE, CK, AY and CL rods.

 

The Edlebrock parts will fit an original Rochester QJet. Part numbers posted by others, above, are correct.

Yes, fatter does mean richer.

Here's another place you can buy DR rods: The Carburetor Shop in Ontario, California (not Canada). 909-481-5816



[This message has been edited by Damon (edited September 23, 2001).]

 

Only if you're not talking about the rods themselves.