Author Topic: Rough running '56  (Read 1019 times)

Charlie Petty

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Rough running '56
« on: May 17, 2010, 01:00:19 PM »
My '56 CdV runs fairly smoothly in neutral, and seems to have good throttle response.  When I put it in gear, however, it runs rough and wants to stall.  I haven't had it out on the road yet to see how it acts.   I just timed it and set dwell.  What should I be checking?   

Offline J. Gomez

  • Posts: 2376
  • CLC Number: 23082
  • Name: J. Gomez
Re: Rough running '56
« Reply #1 on: May 17, 2010, 01:21:06 PM »

Have you adjusted the throttle relay and return check valve? This littler gizmo keeps the idle stable and prevents stalling. Section 10 of the Service manual has the details; also there is an alternative method for this adjustment listed under the June 1956 of the Serviceman.

Good luck..!
J. Gomez
CLC #23082

Charlie Petty

  • Guest
Re: Rough running '56- internal problem
« Reply #2 on: May 17, 2010, 08:36:08 PM »
I think I am on to the problem.  Of seven cylinders tested (couldn't get to one yet), four are at 170 lbs., two are at 150 lbs, and one is at 60 lb.  Car does not smoke; I hope it is a valve problem.  Guess I will tear it down. 

Offline The Tassie Devil(le)

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  • Posts: 12388
  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: Rough running '56
« Reply #3 on: May 17, 2010, 08:54:26 PM »
G'day Charlie,

Before you rush in and tear it down completely, have you performed the "Wet" check?

That is after you have done the Dry Compression Check, squirt a couple of pumps of the Oil Can into each cylinder, and after a couple of revolutions, perform the check again.   Then, before you finish, re-check the first couple of Cylinders just to check, as these ones won't have had the same revolutions as the latter ones, and therefore the oil mightn't have completely sealed the rings.

This will tell you if it is Rings, or Valves.   An immediate raise in the figures will rule out Valves, as the Oil has sealed the Rings, and no, increase will tell you that the Valves are at fault.   A Slight increase will indicate that the Valves are the culprit, but also that the Rings are worn.

Bruce. >:D

'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Charlie Petty

  • Guest
Re: Rough running '56
« Reply #4 on: May 17, 2010, 10:32:21 PM »
Bruce-  I will do the wet test for sure.   THANKS.


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