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Author Topic: 1962 Rochester 4GC issue  (Read 524 times)

Offline StevenTuck

  • Posts: 1055
  • CLC Member # 16507
  • Name: Steven M. Tuck
1962 Rochester 4GC issue
« on: August 03, 2018, 06:34:30 AM »
I have noticed that my rebuilt, twice now, Rochester 4GC idles too high at stops. I can slightly pump the gas pedal and it goes to normal idle. I have to drive it 45+ mph for a mile or more for this to happen. Driving under that speed it doesn't do it. Other than this it accelerates and idles smooth, it just doesn't want to go to a low idle at stops.
1962 Cadillac Eldorado Biarritz
http://bit.ly/1NfPNHE
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Offline Dave Shepherd

  • Posts: 2426
Re: 1962 Rochester 4GC issue
« Reply #1 on: August 03, 2018, 07:46:40 AM »
No easy answer here, checked for binding linkage, weak return spring?

Offline Jon S

  • Posts: 2561
  • Name: J. Schapiro
Re: 1962 Rochester 4GC issue
« Reply #2 on: August 03, 2018, 08:12:25 AM »
Also check the dashpot adjustment.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

Offline StevenTuck

  • Posts: 1055
  • CLC Member # 16507
  • Name: Steven M. Tuck
Re: 1962 Rochester 4GC issue
« Reply #3 on: August 03, 2018, 08:21:45 AM »
I read some google searches. One comment suggested that too long screws being used when the throttle was rebushed could be the culprit. I did notice my screws were longer than the others. I have adjusted the fast idle cam per the shop manual. I also have a factory correct return spring which seems tight enough. The problem existed before I replaced the return spring. I am wondering if my carb is just plain worn out. I didn't want to have my spare rebuilt. I just don't want to waist the money if I can do something to this one.
1962 Cadillac Eldorado Biarritz
http://bit.ly/1NfPNHE
Car Show Signs and Car Photo Books
http://carshowsigns.net/

Offline StevenTuck

  • Posts: 1055
  • CLC Member # 16507
  • Name: Steven M. Tuck
Re: 1962 Rochester 4GC issue
« Reply #4 on: August 03, 2018, 09:22:54 AM »
Also check the dashpot adjustment.
The first carburetor rebuild was back in 2009 and I never adjusted the linkage or the dashpot. The car ran fine and it returned to the idle as before the rebuild. The restoration shop that worked on it in 2017 indicated they had to straighten the top half because it was warped among other things they did. Again I am wondering if this carb is just plain worn out. I hate to have my spare rebuilt if I can do something rather simple to fix this one.

Thanks for your suggestion.
1962 Cadillac Eldorado Biarritz
http://bit.ly/1NfPNHE
Car Show Signs and Car Photo Books
http://carshowsigns.net/

Offline Dan LeBlanc

  • Posts: 4813
  • Name: Dan LeBlanc
Re: 1962 Rochester 4GC issue
« Reply #5 on: August 03, 2018, 09:31:09 AM »
I've had this problem before on 61/62 cars where the plunger in the dashpot was not always retracting when it needed too.  A little squirt of WD-40 on it and working it a few times with my finger and all was good afterward.
Dan LeBlanc
1977 Lincoln Continental Town Car

Offline Jon S

  • Posts: 2561
  • Name: J. Schapiro
Re: 1962 Rochester 4GC issue
« Reply #6 on: August 03, 2018, 10:05:04 AM »
Clean all linkages with carburetor cleaner and ensure there is no binding. Dan's suggestion of WD-40 on the dashpot shaft is a good one. You don't want to adjust the dashpot plunger because they break easily. Since this appears to be an intermittent problem (above 45), something is not as free as it should be. Also clean the choke linkage on the passenger side.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

 

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