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76 eldo convert poor acceleration poor downshifting when I push gas pedal

Started by 76 cadillac bob, October 14, 2017, 06:03:50 PM

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76 cadillac bob

My 76 Eldo conv has a rebuilt carb. I am finding the car appears sluggish and slow to respond and I have to really push the pedal to downshift. I had a 69 chevy stationwagon 350 that had a 4 b carb and it was a really fast car and was very peppy. I am wondering if the carb is working correctly. My mechanic advised it was, I somehow dont believe him? I know weight is different by a couple thousand pounds. Any thoughts on this? or am I expecting too much.CB

Bobby B

Might have something to do with your trans linkage, adjustment, vac, etc. Not familiar with the year/car, but the symptoms you're describing could possibly involve your Trans. My friends dad had one brand new, and it was no dog.  I'm sure someone will chime in....
                                                              Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

"Cadillac Kid" Greg Surfas 15364

Bob,
You have really combined two things. 1. Sluggish performance and 2. requiring full throttle for downshift. The second could be either an out of adjustment or bad  downshift switch.
I would suggest getting that issue straightened out and see how the performance is.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

35-709

The downshift switch will look like the pic. below and be on the driver's side of the carburetor.  Not infrequently the plastic arm will get broken off when a carburetor is removed or installed because the switch was not removed first (or replaced last) which, of course, renders it useless.  Some don't put them on because they don't know what they are for or how to properly adjust them.  Adjustment is easy following the directions in the Cadillac Shop Manual.  I have repaired them if the problem is inside the switch by drilling out the rivets holding it together and putting them back together with 3/32 or 1/8" pop rivets.  You can test it with a continuity meter --- or sometimes if your hearing is good and it is very quiet where you are, you can hear a faint click in the transmission when you activate it by hand, assuming the wire(s) to it and from it are good and the ignition switch is turned on --- car not running   ;D
The Cadillac Shop Manual contains a wealth of information and how-to and is easily found on eBay.

http://www.ebay.com/itm/1976-CADILLAC-SHOP-REPAIR-MANUAL-ALL-MODELS-ORIGINAL-/122724597429?hash=item1c92f4beb5:g:DvEAAOSwbsBXjZT-&vxp=mtr

The Fisher Body Manual is really nice to have also.

http://www.ebay.com/itm/1976-FISHER-BODY-OEM-SERVICE-SHOP-MANUAL-Firebird-Camaro-Cadillac-/362110184190?hash=item544f72eafe:g:LjMAAOSwUuRZxApp&vxp=mtr   
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

"Cadillac Kid" Greg Surfas 15364

Bob,
IF you find you need the switch I just updated my adv. in the classified section for the one I found in my "stash".
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

TJ Hopland

The down shift switch doesn't activate till you are practically on the floor so with normal(ish) driving you don't often hit it.    Makes me wonder if you have other issues?

Exhaust restriction like a plugged cat or critters?   

Choke or some other carb issues not allowing the secondaries to open?

Something not right in the distributor so the timing isn't changing like it should?

Timing chain really flopping around and or maybe slipped so timing just isn't right?     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

James Landi


Before you do anything, check to see if your accelerator pump is functioning.  With the engine and ignition and air cleaner OFF, using a flashlight, check to see if there is a stream of gas going out of the carburetor when the accelerator is depressed...  that's a start -- if there is no stream there, you've a carb issue... if there's a stream present, likely other problems outlined in previous posts.  These engines are responsive if they're in good working order  (aka: ignition, vacuum advance, timing and CARB)

Jeff Rosansky CLC #28373

Also, next time you drive it get out and feel the wheels. Be sure you don't have a brake dragging.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

TJ Hopland

Good thought on the brake drag.   The rear disc are good at sticking with lack of use and infrequent fluid changes.   The front hoses do seem to suffer internal failures more than most cars with age likely due to their routing and sharp bends to stay out of the way of the drive axles.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

76 cadillac bob

thanks all, I will be driving the car later this week, Carb was rebuilt I dont think it was done correctly. I will check switch and make sure it is there and working. I will check for flow as well. Exhaust replaced a year ago, and live in North San Diego County so no woodland critters, maybe a rat or two but not in the exhaust.
I will have Brakes have been checked and not grabbing. I will let everyone know what I find.
CB

Jeff Rosansky CLC #28373

#10
I think the kick down switch is a separate issue. I have a 70 DeVille and I have that switch disconnected. I love to open it up and hear/feel the back barrels but I don't want to be hard on the transmission by making it shift.
As TJ says, just because the brakes are new doesnt mean they are not a problem. When in parking lot/garage, put in neutral and try to push it. I know it is a heavy car but you can tell if something is fighting you...... Just a simple check.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

bcroe

I also don't think its the kickdown switch, or the trans.  That 500 should
have pretty decent performance.  Check your timing chain for slack.  It
need a pretty good exhaust for good performance, no plugged cats. 

Bruce Roe

"Cadillac Kid" Greg Surfas 15364

Bob posted two issues that probably are separate. The poor performance he perceives AND the fact that he has to press the accelerator pedal nearly all the way to find passing gear.  Issue of the kick down as I stated earlier can possibly be a miss adjusted kick down switch.  He said the carburetor was rebuilt and when that happens the switch is normally removed and then reinstalled. IF it is not adjusted correctly or if it is damaged when reinstalled the symptoms he is reporting can result.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

7gen

I had a plugged cat that was causing poor performance when more gasoline was being dumped through the system. Didn't see the problem when just cruising along on the flats but when I started to go up hills or trying to pass, it acted like it had no gumption at all. The cat overheated and caused a burn/melt in the passenger footwell. Might want to feel that area after a long pull up a hill to see if it is hot.

pplaut

My transmissions shifts at 30 and 50 and not a moment before.
I can speed up to 50, shift into 3rd gear and then at 40mph the motor is not racing.
On a different thread, I got the modulator replaced. Dropped the pan, changed the fluid and replaced the transmission filter.
This seems the appropriate thread to ask this question.

Peer L. Plaut
Head Baldie
Baldmen.Com