Help! Carb question...

[ramirezjx]

Hello Ladies and Gentlemen,
My '80 keeps stalling out on me. Prior to today, I would warm it up for 15-20min and it would be good to go. Today I drove around for about 1/2 hr, stalling along as I went. If I do need a new carb, what kind should I get? My car is a 1980, Coupe, 350, 5.7L. w/ AC and Stick(if it matters). Should I go new or rebuilt? Should I go Edelbrock or Holley? Can someone please help me out?

v/r
ramirezjx

 

[petes74ttop]

Hi ramirejx, your description is very vague, I might start with a new in carb fuel filter and while your doing that check to fuel pump pressure.
If your car is stalling from to much fuel you can get a kit and change the needle and seat. Heres a link to help you rebuild it http://www.4wheelnoffroad.com/qjet.html you my also have a bad float or a vacuum leak. PG.

 

[Evolution1980]

Ramirezjx,

I agree with Pete, you may need to supply some more info (if you have any).
The only thing I noticed was that you said you let it warm up for 15-20 minutes??? That's not necessary. From a cold start on a warm day, a minute or so is all you need. In the winters, give it about 5 minutes.

What all have you done to troubleshoot the problem?
How fresh is the gas? Do you smell gas or anything at any time during the drive? What prior maintenance has been done on the car?
It's most likely NOT your carb. Your Q-Jet 750 is a great carb right out of the factory and usually doesn't need to be fiddled with.
When you are driving it (and it's not stalling) is there hesitation at any specific RPM range? What are it's tendencies when it starts to stall? Do you have any problems getting it restarted?
In what condition is your exhaust system?

Our cars are pretty simple. "If the problem's not electrical, it's a vacuum problem." If it's not either of those, it's fuel delivery. That's about it.

Be sure to stop over in the New Member Introduction forum and introduce yourself!

 

[Yoda]

ramirezjx ~ Welcome to the Corvette Action Center Community ~

ramirezjx

I know nothing about engines, but thought I would pass this along.
If your 1980 is a 4-Speed, then you might want to check the engine compartment again

I've heard there were a "few" L82 (350's) out there with 4-Speeds (very early production numbers) but, almost "All" of the others would be a 305 not a 350

Good luck, and enjoy the

(The first New Corvette I ever owned was a 1980 ~ 4-Speed, Red with Oyster interior)

Bud

 

[Evolution1980]

I've heard there were a "few" L82 (350's) out there with 4-Speeds (very early production numbers) but, almost "All" of the others would be a 305 not a 350

Did I miss somewhere where he said he had an L82?:confused You could get the L48 with the 4-spd...

 

[ramirezjx]

Ramirezjx,

I agree with Pete, you may need to supply some more info (if you have any).
The only thing I noticed was that you said you let it warm up for 15-20 minutes??? That's not necessary. From a cold start on a warm day, a minute or so is all you need. In the winters, give it about 5 minutes.

What all have you done to troubleshoot the problem?
How fresh is the gas? Do you smell gas or anything at any time during the drive? What prior maintenance has been done on the car?
It's most likely NOT your carb. Your Q-Jet 750 is a great carb right out of the factory and usually doesn't need to be fiddled with.
When you are driving it (and it's not stalling) is there hesitation at any specific RPM range? What are it's tendencies when it starts to stall? Do you have any problems getting it restarted?
In what condition is your exhaust system?

Our cars are pretty simple. "If the problem's not electrical, it's a vacuum problem." If it's not either of those, it's fuel delivery. That's about it.

Be sure to stop over in the New Member Introduction forum and introduce yourself!

All,
I want to thank you for the quick responses.

Evo,
I'll try to answer your questions as best I can.

What all have you done to troubleshoot the problem?
None. I'll start with the fuel filter this weekend (Thanks Pete)

How fresh is the gas?
The gas is fresh. I was driving it around before this Wednesday. I only fill it with the highest grade gasoline. Super Plus, Premium, whatever that particular station calls it.

Do you smell gas or anything at any time during the drive?
I smell gas whenever I start the car.

What prior maintenance has been done on the car?
As of now I have done a full tune up and changed the valve cover gaskets. I've only had it for 3 weeks. I also did the brake lights, signals, horn, , battery, but I guess those are just details.

When you are driving it (and it's not stalling) is there hesitation at any specific RPM range?
None. Drives just fine once it gets going.

What are it's tendencies when it starts to stall? Do you have any problems getting it restarted?
No problems whatsoever in getting it restarted.

In what condition is your exhaust system?
Not that I know of.

I know nil about cars. I do want this to be a good learning experience. Maybe I should have just gotten a Neon and called it a day!

Exactly how do I find out what I bought (305 / 350)??
Another question is... At at how many revs am I suppossed to be idling?? Before this mess I was idling at between 600 and 700 RPM's. Isn't that a little low??

Again thanks to all.

Remy

 

[GerryLP]

All,
I want to thank you for the quick responses....

Exactly how do I find out what I bought (305 / 350)??
Another question is... At at how many revs am I suppossed to be idling?? Before this mess I was idling at between 600 and 700 RPM's. Isn't that a little low??

Again thanks to all.

Remy

The numbers stamped on the ledge just forward of the passenger side cylinder head could shed some light on this question.

Manual transmission-equipped cars tend to have low curb idle rpm settings; however, the idle curb speed is not as important as the fuel mixture set in the carb and the ignition timing. Once these are correct, and barring any vacuum leaks, the curb idle setting is just a matter of turning an adjusting screw on the carb's accelerator lever.

Post an image of the carb from the front side and perhaps we can tell you if the anti-tamper plugs have been removed, and if so, we can give you a good ball park mixture setting for your idle.

 

[Evolution1980]

Exactly how do I find out what I bought (305 / 350)??
Another question is... At at how many revs am I suppossed to be idling?? Before this mess I was idling at between 600 and 700 RPM's. Isn't that a little low??

You can determine your engine by checking the VIN.
Check the 5th digit.
H = LG4 305ci 180hp
8 = L48 350ci 190hp
6 = L82 350ci 230hp

As for RPM's, 700 sounds about right. I think my car with an auto trans, in gear, is supposed to idle around 700-800rpm.

For checking your VIN and other info about your car, I suggest checking the CAC's Model Center. Specifically, here is a link to the sub-page regarding VIN breakdown.

I'd also suggest the assembly manual for your car (or a Haines manual).

 

[Hib Halverson]

I can't help too much with the stalling because insufficient information as to the nature of the problem was given. One question...does the stalling only occur before the engine warms to operating temperature or does it stall all the time (ie: cold or warm) when it should idle smoothly.

I can offer some information on other issues in this thread. First, all 1980 Vettes, except those sold in California, have 350s. Only cars sold in CA had the LG4 5-liter engine. It's unlikely your car is an LG4 because you have a manual trans. No LG4s were built with four-speeds. Of course, with a 28 year-old car it's possible someone converted it to a manual so....how to tell the difference? Easy. LG-4 was GM's first engine with digital engine controls. If you have that engine in your car, there will be an oxygen sensor in the exhaust close to the engine and there will be a computer in the battery well behind the driver.

Lastly, the suggestion of "Haines" manuals in an above post. I'd pass on the idea of Haynes Repair Manuals because they are condensed and contain inaccuracies. If you are going to start DIY service of your '80, buy the factory service manual.

 

[6880 Mike]

...1980 Vettes, except those sold in California, have 350s. Only cars sold in CA had the LG4 5-liter engine.... No LG4s were built with four-speeds...

Roger that. The 4 speed was available with the L-48 in 1980. The optional L-82 was not available with the four speed due to emissions certification problems. The speculation is that as few as four very early 80 L-82s had four speeds, but take that with a grain of salt. If emissions certification for the 4 speed L-82 was the bogeyman, it isn't likely GM allowed these vehicles (if they were built) to have been sold to the public.