More stupid questions

[davette59]

I know some of you think these are stupid questions but my experience was with working on pre 1960s cars. besides, I know you guys like to answer questions and try to help. I have just replaced the valve cover gaskets and believe I need to replace the carburetor (absolutely no model number visible). When car sits of a while I need to crank it of a long time to get it to fire. I suspect the carb is letting the gas drain back out. I have attached a site with pictures and questions regarding the engine and carb on my 78 Avanti. There are some unknown parts (to me) and others that seem not to be connected. Any advice is welcomed. There is a loose brown wire near the carb but it is not an electric choke unless the carb was changed which I think had been done.

http://s1213.photobucket.com/user/davette59/library/1978%20Avanti%20II%20%20Carburetor

Dave the Dunce!

P.S. Excuse the filthy engine, the car had been sitting for years before I bought it and the body shop got sanding dust all over it.

[stall]

There are no stupid questions Dave. In my opinion your the victim of our lousy gasoline. The new 10% ethonal stuff evapoarates very quickly. If your car runs good once started then it's probably the gas. The only cure I've found is to use an electric-fuel-pump to prim the carb. I'm sure others will chime in but thats my best guess.
Murray

[davette59]

Didn't think about the fuel pump letting the gas drain back. Not sure if that could be it since the gas tank is higher than the fuel pump. Good idea though. I do know that if you have an electric pump, you need to have it turn off when the engine stops. If you had a wreck, you wouldn't want it to keep pumping gas all over the place.
Oh, I do use pure 100% gas with no ethanol. Over $4 a gallon. YIKES! I may start using some Stabil.

[Mike Van Veghten]

Dave -

The gas is NOT draining "back". the only way this "might" happen is if the car were laying on its side and the fuel inlet needle stuck open..! Both highly unlikely, right ?

Just tap into an ignition "on" wire, then the pump is on with the key and off with the key. Some go even farther with a switch in the oil pressure line to shut the fuel off with an engine failure.
Or, there's a switch available that senses a crash (Ford seems to be the likelyest switch) and shuts off the pump.

Mike

[Alan]

Most of the hoses and broken off pieces are parts of the smog control devices.

[JimC]

I went to a local pick and pull type yard and got a perfect safety switch from a Ford Minivan. It's an electric switch that trips on impact. Ford minivans keep these on the rear passenger side near the corner. If you open the rear hatch there's a service panel and it's right there looking at you.

Is your current carb a 2bbl or 4bbl carb? My 2bbl was going out on me, so I got a new intake manifold and upgraded to 4. Truly a good choice! I wouldn't go back. As far as the long cranking, it could just be fuel evaporation, but it could be a poor fuel mix, or something else entirely. How long is it cranking? Do you pump the gas before turning the key?

[davette59]

It is a 4 bbl quadrajet carb on a Corvette 350 ci engine. Yes I do pump the gas before trying to start. It takes 10 to 15 seconds before it starts to fire. This doesn't sound long until you try starting a car or count it out. It's almost like when you run out of gas, put more in and try to re-start it. It's like all the gas in the fuel bowl has gone and has to be re-filled before it starts. If I try and re-start after shutting it off it starts immediately. I haven't timed how long before it becomes hard to start but I would guess about a half hour.

[avantilover]

Gas prices back home today are $5.32 for 89 octane and $6.00 for the 95 Octane I use for all my cars.

$4.00 is cheap, enjoy it whilst it lasts.

[Alan]

Dave; There are 2 plugs in the bottom of those Quad's, that can leak gas. You could take yours to someone that specializes in those carbs and have it rebuilt or replaced with one they think would be a better replacement.
John C; in 72 I went to Japan and tried to rent a car. The car rental guy asked me if I could afford to pay for the gas, since a Shell station was close enough to see and their sign said $2.25. When I got there it was $2.25 a liter.

[davette59]

Wow, I'll complain no more about gas prices me thinks!

[davette59]

There is a place on the net called "guaranteed carburetors" that sells rebuilt carbs for my car for $179. They come field tested with all the proper adjustments etc. I'm just not sure if they will take mine for the core since it doesn't seem to have a model number on it. Well, it's a good price anyway. They can give me one that is an exact fit for my Avanti and it comes with a full warranty too. Guess I'll go for it since I'm pretty sure I need a new (rebuilt) one anyway.

[55 56 PREZ 4D]

Another way is to put the electric fuel pump on a manual switch.
Mount the switch out of sight under the dash. Put an inline fuse in the circuit. Mount the pump as close to the tank as possible.
Turn on for a few seconds prior to starting the car, then manually turn it off. The pump will not be needed when the car is started often.
You will hear the pump sound change when fuel pressure raises enough to start the car.
Safe, simple.
The carb may not be bad. The new fuel will evaporate just the same on a new carb.

[Rerun]

Dave,

It appears that your 350 is very similar to mine. If you look behind the alternator, on the front of the block, there will be a stamped 8-digit alphanumeric code. This will identify the GM plant that made the engine, the month and day made, and a description code (probably CLM as the last three digits). CLM would indicate an L48 motor used with automatic transmission in the Corvette and Monte Carlo.

As far as your hose routing issue, I have taken a series of pictures of my engine that should be helpful in sorting out yours. I hope that this helps.

http://s226.photobucket.com/user/bradley71771/library/78%20Avanti%20Hose%20Routing

[Rerun]

BTW, the brown wire is for the throttle kicker, which increases the idle speed when the A/C is turned on. This kicker is missing from your carburetor. See the pics of mine. It's on the left front of the carb.

Also, the solution to the starting problems may be simpler than some of the suggestions above. I am running a totally stock system with the Quadrajet, and mechanical fuel pump. It works just fine. I would suggest that you first resolve the issue with all of the hoses. A vacuum leak can create problems. Also make sure that the choke closes properly (fully), and that the vacuum pull-off is operating properly (opens choke about 1/4" as soon as engine fires). I noticed that the vacuum pull-off on your carb is a different style than mine, but the function is the same.