1958 Corvette 2x4 270HP Carburetor Problems
As I have been preparing our 58 for my upcoming PV at the Frisco, TX Regional, I've encountered some carburetor problems. The car that had always started after setting the choke, but now labor's to start. When it first starts it acts like it is loading up with fuel before clearing out. Once warmed up the car idles and drives fine. We are leaving with the car tomorrow Thursday (October 14) for the Nebraska Chapter Event and don't have time to work on it. We will arrive in the Dallas/Frisco area on Sunday (October 17) evening, if there is anyone that would have time to look at the car before my PV on Thursday (October 21) morning I would appreciate the help.
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Re: 1958 Corvette 2x4 270HP Carburetor Problems
Alden it sounds like the choke isn't setting fast idle properly.
Remove air cleaner when cold. Hit throttle a few times and observe the choke butterfly on rear carb. It should close with a small opening at front of air horn(iirc apx 1/8").
If not, it could be a loose clamp screw on the butterfly linkage. Or it could be a sticky brass counterweight inside the choke mechanism.
If so you'll have to remove the black cover(3 screws) and remove and clean it. Take note of position of black cover and internal coil spring tab to mechanism lever.
If this fixes it you may have to adjust the butterfly linkage and properly set the fast idle RPM to spec. I don't recall exact fast idle RPM so check JG/Service Manual. Apx 1500 RPM?
Rich -
Re: 1958 Corvette 2x4 270HP Carburetor Problems
Rich has it covered but another perennial problem with these old WCFBs is the choke pistion becoming sticky or seized; it is located under the black cover and you can see the action as you work the choke plate. The ass'y should move freely and without interference; if not the piston channel may need cleaned out. More diagnosis would help; is the car spewing black smoke out the rear during a cold start ?
When you "set the choke" before cranking remove the air cleaner and see where its resting, etc..Last edited by Frank D.; October 15, 2021, 10:52 AM.Comment
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Re: 1958 Corvette 2x4 270HP Carburetor Problems
Richard/Frank:
We have Once again adjusted the choke and seems to cold start better, but I feel that the fast idle is still to low. Also when it cold starts water drips from the tail pipes until it warms up. Any suggestions?Comment
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Re: 1958 Corvette 2x4 270HP Carburetor Problems
Condensation coming out of the tailpipe is normal if the car hasn't been driven a long distance; it should quickly clear up...
Not sure what the "too low" fast idle would be but this manual covers all of the adjustments:
Here are the dual quads on my 61 starting up cold, the adjustments are tweaked a bit since I live in central FLorida but you get the idea, also shows a typical fast idle and closed choke plate position:
I adjust the choke on a cold morning (per your area and time of year) as Rich indicates above and that is done with the throttle linkage held completely open. I find that setting (which ignores the index marks) works perfectly on several sets of real and clone dual quad setups I've had over the years.Last edited by Frank D.; October 18, 2021, 04:31 PM.Comment
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Re: 1958 Corvette 2x4 270HP Carburetor Problems
Yes, and in that manual on page 54 describing the adjustment to raise the fast idle once the choke linkage is set properly. There is a tang on the lever that you bend against the fast idle cam to get 1800 when on high spot on the the cam. Red arrow in photo.
wcfb_fast_idle_adj.jpgwcfb_linkage.jpgwcfb_tab.jpgComment
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