My '64 is wiggly and bouncy and has an air suspension system that doesn't seem engaged

I've had the '64 convertible for 4 years and it's great, with several improvements, notably front disc brakes and an Edelbrock carb which completely solved my hard starting problem. The car was bouncy when I bought it and I put new shocks in, which did not seem to help. I have not wanted to invest in new coil springs if I did not think that was the problem. The car has air valves in back by the gas cap which look factory-installed(welded and painted), but I assume they are not. Attempting to add air raises the car an inch in back, but the air leaks out quickly so I have not been able to drive it with air added. I see some negative remarks here about air suspension. Would it be a good idea to have the leak found and fixed in this air suspension system and see what happens? Or replace the coil springs? Or just let the car bounce and jiggle on bumps because it's old and it's a convertible, since convertibles always have some "cowl shake"? It rides wonderfully on the highway. Or, perhaps I need to find a suspension shop to look it over. Regular mechanic sees nothing lacking in the suspension from an inspection on the lift. Thanks!

In the attached photo, one air valve is connected to nothing, and the other is, and raises the car when pumped, but leaks out within a minute. 

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The air valves are not stock —but aftermarket 

Do you have air bags ( instead of coil springs  ? ) or air  filled shocks to just lift the rear  ? 
What do those air valves connect too —if anything ?

I would first  fix the air leak if at all possible and see what that does to  possibly reduce your ride motion 

As it is currently installed —try to get it to work correctly as that could be the easiest possible least expensive solution 

These Cadillacs  convertibles do not have —cowl shake - when suspension is correct but are a  rock solid cloud 9 ride  —and steering with one finger - Amazing !

Having a suspension shop tell you what you may need will give you some insight   as to what is needed 

I assume it is the rear of the car that has the added movement 

The rear control arm bushings and the ball  joint bushing above the rear axel should be looked at for wear causing the movement 

In my own opinion the 64 Cadillac stock suspension ride is the very best Cadillac ride of them all and I have owned a number of years and—just  one of the reasons— my 64 convert is my forever Cadillac convertible 

IT RIDES LIKE A CADILLAC —- applies here !!

I try to express how good the stock ride of our year Cadillacs  is —-as some acquire these cars with suspension that is much less than reasonably good condition and have to decide which direction they choose to take their restoration at that point 

That should help some 


Thank you, Tony, I will try to get that looked at this week. I will feel stupid if after 5 years with the car it turns out the aftermarket air ride needed inflation. I just never really thought about it. I suspect the leak will be easy to find. 

Could you let me know which Edelbrock carb you installed. I want to change mine but not sure which one to get. 



Yes, Richard, I got the Edelbrock 1406. Before that, I kept fiddling with the carb on the car and I had to pump the gas 15 times to start it, and sometimes used starting fluid sprayed into the carb. I also changed the intake manifold which seemed to have a crack and leak. So, it's been 4 years so I can't recall which thing had the most impact or what I did first, but once I made the change the car starts cold on one tick in half a second, properly runs fast on the electric choke and then slows down with a tap on the accelerator. Has more power and is smoother, so I'm not going with Carter or Holley, I love the Edlebrock. I bought it on Amazon for $400. I did not make any changes to the car in terms of vacuum or anything else, as some have noted here. It has the electric choke and that seems to work fine.

Thanks! That is my exact problem starting. I'll change the carburetor and then check for manifold leaks.

Thanks again,


I would think it would pay for itself by being somewhat more fuel-efficient and also not wearing out your starter and solenoid. I'm recalling now that there is a transmission step-down function that I didn't understand and I just left it off. I don't think I have a problem with the car stepping down a gear on the highway when you push down hard on the accelerator but I probably did not notice that either way. 

You really do not need the passing gear (step down feature on the carb for the trans ) as mine has been disconnected for just that reason for years 

I have never had a problem at all passing anyone I desired too at pretty much any speed we are going with the torque these engines produce and the way the Th - 400 produces its power output 

I see why you are not missing the step down feature - as it is not needed in my opinion owning the car since new 


I do second using the Edelbrock 1406 on my 64 429 - with the turbo trans as a replacement for the stock Carter carb ( a Carter carb but improved ) 

A plug and play easy installation using all the stock gaskets from the Carter carb to the intake

Need to plug the PVC inlet in the black spacer  as you have two now  with the 1406 

Kept the stock gaskets and black spacer - no intake heat channel modification ( plugging ) on mine by choice 

I did have a need to go two stages richer on the jetting  to get my plugs to burn a brown paper bag color ( correct color ) as the plugs were burning whitish ( lean mixture ) before doing that 

Changed the primary jets and metering rods per Edelbrock techs advice — call them with the numbers on your parts 

Went two sizes  richer on the primary jets and metering rods ( for ethanol fuels ) 

I do remember using the original primary jet size ( from the front of the carb ) to replace the carbs secondary jets ( located  to the back of the carb ) as that increased the secondary  jet size just a bit 

The stock air cleaner will no longer work with the bigger  Edelbrock venturi 

Russ ——sells an adapter for the stock air cleaner to work if that’s your need 

I chose to go with an after market K&M air filter to improve the carbs breathing and engines performance 


Tony, wow, that's great detail. I have never understood carburetor jetting so I did not make any changes. However, based on your post I'm going to pull out a couple of spark plugs and look at the color. I think I did get a modification on the air cleaner from Jason and I was concerned the hood might touch it when closed, but no problem there. 



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