My good old 83 Chevy Custom is having some engine problems. It doesn't want to start in the cold until I put a little gas into the carboreator manually. Then, it will idle fine and if I hit the gas hard, it runs fine, but between about 1100 and 1700 rpm, it will run then kick down to about 500 rpm, then back to 1700 rpm, and repeat.

At first, I thought it was the fuel pump, thinking it just wasn't getting enough fuel to it during those rpms, but after replacing it, the problem still exists.

My next thought is that I should change the carboreator, but thought I should check in for advice first.

Thanks

83 was trickier than some with carbs. What engine and carb is in this? This seems like it's all about choke probs,

T
Tom Greenleaf - MetroWest Boston - USA
http://www.acsource.com/

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http://www.autoacsystems.com/tomgreenleaf/

350 engine with I believe a quadrajet carb with an Edelbrock High Rise manifold.
It doesn't have a choke, so I was planning on changing out the carb sooner or later. Then this started happening.

I am thinking it about has to be the carb since I am getting good gas pressure to the carb, but it is still sputtering in that range.

Should I go to a manual choke carb or try to find an automatic choke?

? What happened to the choke? Is it there and disabled or parts missing? It'll matter a lot. The carb for this is pricey but a rebuild kit is cheap but takes some real know how to do right.

I think this is set up for an electric choke and if wiring is still there and operative for that then I would get a good original core and rebuild it. Keep the choke and keep it automatic. Trying to make them manual for vehicles that weren't ever designed for them is a nightmare and best anti-theft trick anyone ever thought up.

Right now I think you are battling with the fast idle step cam which must still be there and can't move freely and bounces around when revved up.

The original quadrajet for the truck lines were fine - cars were a pest.

So for now tell us what's there. You didn't seem too sure what carb it had. Should be a rochester quadrajet or some Holley replacement would have been a choice along it's life,

T
Tom Greenleaf - MetroWest Boston - USA
http://www.acsource.com/

_________________________________________

http://www.autoacsystems.com/tomgreenleaf/

I am thinking that the guy that originally owned it took it off to try to get a little better gas mileage.

I am going to go ahead and upgrade to an electric carb, and see if that solves the problem. If not, I'll have to try something else.

Changed the carb today to a new Edelbrock one and the problems still are happening.....

What should I try next????

I guess this means the choke and missing parts can be ruled out now and that choke is now working -right?

With the funky idle speeds still being the problem it boils right down to the cable that moves the carb or anything attached (cruise, kickdown cable - whatever) With the cables all off the carb, just reving it by hand should behave if you want to try that as it's VERY unlikely for two different carbs to have that exact behavior by themselves. What is used for idle speed control on this? If need be at this age disable that and use a real idle setting not an electric motor or vacuum controlled idle speed control and then fix those - I don't know what might have been used for that for this as things aren't even orig anymore it will take the basics to figure it,

T
Tom Greenleaf - MetroWest Boston - USA
http://www.acsource.com/

_________________________________________

http://www.autoacsystems.com/tomgreenleaf/

I think I figured it out now.....I think it is the vacuum advance. I played around with it and when I unhooked it, I was able to fix the problems. I am gonna go to the NAPA tomorrow and see if this will fix the problems.

I will keep you updated!

Just thinking here...
check the vacuum advance for sure...but it may have a problem with the pickup coil/wires in the distributor...common problem for them to fray/pull apart when advanced...you can check them by looking at them and lightly tugging at them..sometime it will finally break all the way..should have I think a white wire and a green wire..
If so .replace the pick up coil...

Just a thought..

Jim