What's the best and not so best modification you've done?

Would love to hear what modifications you've done to your Caddy that you are very happy about; and those that you wished you'd never done.

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A very very good question to be starting this thread 

Good :

An Edelbrock 1406 carb that required rejetting  to be correct — 64 - 429 

Enjoy — the timing vacuum port — the updated  Carter carb  design  that offers a timing  curve advance 

Radial tires that improved performance - lowered the car one inch - better cornering and stopping  — better gas mileage and smoother ride than  factory stock tires

All rubber gas line updated for ethanol fuel

Raybestos brake shoes  always — all around since new 

All hoses and rubber front to back - including motor mounts - trans mounts etc 

All brake cylinders and Dot 4 fluid 

Trans fluid and filter change 

Power steering fluid change 

new timing chain and gears 

3 water pumps —in 56 years 

Driver exhaust manifold that cracked - 

Stock muffler replacement - pipes were solid 

Car completely gone over in 2006 and aprox 6,000 miles since then as only used on great weather days — a convertible De Ville that truly turns heads 

Wire rim hubcaps from a different year Cadillac  - still have stock caps also 

Love the car as it performs stock which is a kind of perfection to me and the reason it has been around since brand new 

Constantly maintained and enjoyed  for 56 years - top down - turn key - just waiting for the sun to come out 

All front end checked and replaced as needed - the car is tight stops and tracks perfect - one finger steering 

A Spectrum air cleaner as  an option for the Edelbrock carb to improve the carbs air flow 

Autolight 45 spark plugs to replace the stock plugs ( More durable than stock )

New cut pile carpet 

Complete AC gone over and parts needed replaced - will be doing that again soon to make temp cooler 

Not at all sorry for anything done above 

A great car to have as an Antique due to the quality of the parts built into the car from day one at the factory that hold up great after 56 years ( 2020 ) which is a long time for a car to be enjoyed by anyone 

Just - Love my 1964 Classic Antique Cadillac - as it says a lot about its Gear  Head Owner to the masses — AMEN 

Stay Safe 

It says "Modification" Tony, not a friggin full service history and what ya had for breakfast, ya fruit loop.

So far I'm very pleased with the whitewall tires and lowering it 1".  

Right now I'm in the midst of a Holley Sniper fuel injection system install.  It's been a chore and it's not running to spec yet so I'm reserving judgment on it.   Initially the start up and acceleration has been phenomenal but it's got some quirks that aren't so endearing.

Clovis up in Canada did a fuel injection fit up. He also spent a lot of time on it, but my understanding is, it worked very well once sorted. Go through the help section, bound to be a link in there on it.

Excellent question! Here's my list for my 1964 Coupe de Ville:

Mods I am Very Happy About (True Mods):
- Pertronix Ignitor III Ignition and Flamethrower III Ignition Coil
- Edelbrock Performer 1411 750 cfm carburetor and modified intake which included porting the front intake primaries to match the Edelbrock 750
- Accel 8MM SuperStock 5043K spark plug wires (black, removed yellow lettering to look stock)
- Converted clock to quartz 15+ years ago thru ClockWorks (still keeps perfect time)

Mods I am Very Happy About (Available Options for my car that I updated):
- Power Vent windows (always a crowd-pleaser & conversation item when showing car and nice convenience to throw in air from right side)
- Controlled Differential (posi, limited-slip rear end, more sure footed if ever needed and can 2 those 2 tire fish tail burnouts!)
- Changing color from factory Bahama Sand to factory Sierra Gold. (Bahama Sand is a classy color but really love that gold)
- Added optional cross-grain vinyl top. (I think it adds another touch of class and contrasts well with the gold)
- am/fm - added the factory am/fm not long after buying the car just to pick up more stuff.
- tilt steering column - easier in and out, and was a great learning experience (a lot to change)
- thicker 75 Series from anti-sway / stabilizer bar. Stays very level in corners now.

Mods I was not Very Happy About
I have to preface this by saying when 1st bought my 64 CDV I wasn't sure where I would eventually take it and was more open to trying different things.  After a few years I decided to go after a stock look, while continuing to utilize performance upgrades such as Pertronix that would  not take away from stock look. If I get into a 2nd car it will be more resto-mod and will probably run pretty wild with wiring, lighting, and performance items but for me with my 64 CDV it is about keeping a stock appearance. 
- Dual Exhaust and Flowmaster mufflers - Boy did it sound good and was happy with it at first, especially in my hot rod heart, but was not what I was after and removed after a few years and went back to a stock exhaust set-up
- Started adding some "Fleetwood bling" to my 64 CDV including steering wheel center horn cap with Fleetwood wreath, bench seat side trim with Fleetwood chromed outer bead, Fleetwood rear courtesy lights --> All of these were removed and replaced with deVille correct items.


I had a bagel and coffee for breakfast 

Modifications means things changed upgraded or improved to me 

Clovis made so many modifications to his 64 sedan ( under the hood ) all at once I am not really sure the car is running at all at this time ( or very well ) 

Last check he had to install a fuel pump inside his gas tank to have enough fuel pressure ( at a idle ) for the Fitech fuel injection he was working through installing to  possibly be working correctly 

There is a fine line between doing and over doing regarding  intended improvements 

I have sent him a personal message to find  out  how the car is doing but have not gotten a response so far 

As I see it no individual has the same technology and test equipment available that General Motors does so to much modification can cause more problems than Improve  the performance ( mostly engine ) 

Then the question comes up as to how you evaluate the changes made to know you made things better than  they were stock 

If  improved engine performance is the goal —-only running the car against a clock would show any improvement in performance 

Sometimes best to leave well enough  alone especially for the kind of use these luxury cars are intended for 

Just my own 2 cents — on doing modifications for the purpose  intended for an early 60’s Cadillac— Luxury Cruisen 

No one is into high performance more than myself ( period ) but some confuse the large cubic inch engines in our year cars for race performance engines which they will never ever be 

Extensive modifications can actually devalue the car for future sale as well 

It  looks like a complete drive train change would get you more performance than tinkering with the 390 or 429 engines to squeeze out what you can regarding performance from them but that is a whole other mind set if that  is your intention 

Stay Safe - 60’s Cadillac Lovers 

Couldn't agree more with your post.  My interest in installing FI is to improve reliability and the overall driving experience not about nursing more power out.  With the exception of cutting a hole in the fuel tank, the install hasn't really changed the stock condition and could fairly easily be returned to stock...I've saved all the take off parts.

Looking under the hood the untrained eye wouldn't really suspect it was anything but stock.  If this experiment doesn't work out then I'm fine going back to the carb.  The way I see it, GM didn't have the advantage of 50 years of automobile development available to them when they designed this car so this is just icing on the cake.

If I can make some mods that increase the safety and reliability of this car which in turn gets me and my family out in it more often then I consider that a win!


Your Fi motivation is a good one from your post 

In Clovis’ s case his intention was to improve performance but mostly  to improve gas mileage 

In his case under the hood does not look at all stock with additional hoses and canisters filling the engine bay which he found needed for the system to work as it should in his case 

Clovis is our mad scientist ( exceptional  talents skills and credentials ) so if anyone could get all that stuff to work as it should he is the man 

Not really sure how it all worked out as he has not been around for a long while ( I do miss his input ) 

Clovis did a thread on updating his AC system that is a must read if restoring the comfort control in a 64 

Extensive detail about bringing the system up to date from soup to nuts 

The tread has been an inspiration to  me and given me enough info to be confident to jump in and restore mine 

Stay Safe 

The very best test —to evaluate  performance upgrades would to use a Dynamometer- which few have available but the very  best high performance shops 

When my car was new to me and still stock 22 years ago, I put in a first gen Pertronix and was really impressed with it. The next best thing was disc brakes. The third and something that I highly recommend is to ditch the original steering box. There are a lot of options but what I am using is a 1970 Monte Carlo SS box. It bolts right in, uses the same pitman arm etc and has 2 1/2 turns lock to lock with variable ratio. You would not believe what a difference this makes. I picked it up at NAPA and they took my old one as a core. 

I have since gone totally off the reservation and built my version of a CTS. Too many mods to mention but maybe I will throw in one more. I made an adapter plate to allow me to use Chevy oil filters. That also allowed me to put on an aftermarket engine oil cooler which increased my oil pressure on hot days and when stuck in traffic. It really works.


I see you own your 62 for a very long time so she is  surely a keeper for you 

Real good looking  62 CDV 

I find the steering box exchange info very very interesting and filed the info 

Thank you for that 

Stay Safe 

Tony, she really is a keeper. When I shuffle off she will go to my daughters. I put a heck of a lot of effort in to building a car that is unique and fun to drive. Now that I have it, she stays in the family. I discovered the steering box interchange on Hemmings. I'll see if I can find it again and provide a link.



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