Edelbrock 1406 swap from Carter...still a completely unsatisfactory experience

Thanks again for so much assistance on this swap from Carter AFB to Edelbrock 1406. Since I posted last, several things have happened and I'll go into some detail for those who might wish to attempt this. May to be too much for others.

But to recap, I put in the 1406 and it would not stop leaking from the choke side, despite 5 tries at installations with new gaskets. I called Edelbrock and they said "Our carbs don't leak. You're supposed to use an adaptor. Buy the Transdapt 2064." So I ordered that adaptor and simultaneously ordered another new Edelbrock 1406 in case the adaptor didn't stop the leak and I had a bad new carb.

The Transdapt 2064 actually DID stop the leak. I also removed the Cadillac metal shim that goes over the gasket, and of course the Cadillac phenolic spacer, since there wasn't room for it(without installing new studs OR going up too high and hitting the hood when closed). 

Result? The instant starting I wanted, that's what my Carter didn't do. I had to pump the car 20 times and still it might die, and ran badly until fully warm, possibly stranding you in an intersection.

NOW? MORE PROBLEMS. The car starts fast, with the electric choke closed. It idles higher, which also helps, but as soon as you tap the accelerator, the idle goes down, which means your brakes and power steering don't work. But let's assume I could fix that.

THE BIGGER PROBLEMS--The brake pedal feels totally different! It grabs, causing a locked wheel and skidding. Once you learn to moderate brake pedal pressure, it feels "funny", doesn't feel connected to the brakes, and also doesn't return upward as fast, like everything is in slow motion. And, the car doesn't shift gears upward well at all, so you are stuck in 2nd gear for too long and the car is straining but won't upshift. Eventually, over 30 mph somewhere, it does shift, but then of course doesn't downshift because the transmission downshift doesn't work because you cannot mount it to the Edelbrock carb. Even Jason has not found a fix for this yet. AND, the car doesn't drive very well, when you push the accelerator, it makes a bit of a roar, but doesn't immediately pick up speed. It's a Cadillac, and it's not smooth.

WHAT I DID NOT DO YET--I didn't adjust the mixture with the two front screws. Most people said the car drove well as is, out of the box, so I'm trying that first. But today I will run the car to warm and adjust the mixture. But that won't fix the vacuum issue where the brakes are no longer right. I put front discs in only a few weeks ago, but with the Carter carb, the action on the pedal was good and I never got brake lockup like I'm getting now.

WHAT ELSE I DIDN'T DO--I have not found the choke tubes I'm supposed to plug inside the intake manifold. I've looked at all the photos on this site and done other searches online and I still don't know where they are. I'm told I should put a screw in them and cut it off at the top. Probably have to buy a tool for that, I only have a battery-powered Dremel.

IN SUMMARY--I will send back the unopened new carb. I will fiddle a bit more with this one, but I really think I just want a newly rebuilt Carter AFB. The car drove fine with it once warm, but obviously had a defective choke. Now I have a car that starts fast, doesn't drive well warm, doesn't fit the trans kickdown switch, doesn't fit the air cleaner(I'm still driving without one, don't have the air cleaner adaptors yet) and messes with the feel and reliability of my power brake system. 

I do wonder if the Transdapt has messed me up somehow. But if I switch back to the original phenolic spacer instead, the carb will leak again, who knows why because it appears to be a tight seal and it takes time to keep trying combinations of spacers and shims and gaskets. I did put it all in with Tony's instruction on the proper order(I think it was metal shim on top.)

For now, still trying. Thought this would take one day!! Has been a few weeks. 

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My experience was that, after eliminating the exhaust heat issues, my 429 ran significantly better after I installed an Edelbrock 1406 and then a 1411. Everything I did afterwards was to tweak an already better runner by engine. I have also been in contact with a total least a dozen others over tg years that had the same positive experience.
If you have done nothing to block the blast of fire hot exhaust gas from getting to bad of the carb that might be part of the problem once everything heats up. If the head to intake port had been blocked you would see temps max out at about 195 to 200 degrees. That is fine even with a metal spacer, however, an insulator spacer would keep it even cooler..With your exhaust channel open you are getting 300+ degree temps. That is not good. Since steps to eliminate heat have not been performed it is hard to gauge what is going on other than to conclude this reinforces the fact that extreme exhaust heat will cause issues. You could swap the vacuum advance hose to the LH full advance nipple, to perhaps have better low rpm and idle response, however it would address the heat issues first.

I've certainly paid close attention to what you say as you are the voice of experience here, and I'm not. But, the carb leaked under every condition until I put in the Transdapt adaptor, which stopped the leak as Edelbrock tech said it would. But it doesn't run well at any temperature. When the engine is cold, it starts fast, that's what I wanted. But then, even half warm, it's not good, well before there are exhaust heat issues. And the "stuck in 2nd gear" problem is weird, it just won't upshift until 35 mph so the car feels very odd, chugging in 2nd at high rpm, then the stalling, even as I keep raising the idle and readjusting the mixture screws. I was quite happy with how it ran before, just not with the starting. Probably all I needed was a new choke on the Carter, but since I'm this far in, I'll replace with a rebuilt Carter. I don't want to use up any more of the summer tinkering. If I put it in a shop for more experienced adjustment, I think I'll just generate a $300 invoice with no magic fix. I'd be happy to pay it if that would work and I could be done. But I want the car to shift right, and my only evidence is to go back to what I had and just have better cold start. 

Drop and punt is often the best course of action in situations like this.


All due respect --you need a good mechanic to get your car back to running as it should
All you problems are carb related and can be resolved
Just think you took on more than you were pepared to handle in doing the carb replacement this time around
The info presented here is really geared for those very mechanically inclinded to fully understand the data presented to answer the questions asked


Yes, you are correct, though I think in this case the setup as is cannot be improved by a mechanic. You should not change a carb, which I've done many times, and have the car have a delayed upshift. With the variety of issues, it's not about turning screws or even rejetting. But the instructions on this site have been invaluable and I thank you for all. 

The shifting of the TH400 trans is controlled by the vacuum coming off the-- back fitting- of the the stock Carter carb
That is what the other metal line going to the back fitting of the Carb is doing that you questioned earlier
Check that entire line going --from the back of the carb to the shifter modual control on the side of the trans
Some of the hose is rubber and subject to splitting (old)
You are looking for --splits in the hose and any air leaks from the carb to the trans vacuum shift modual
Be sure the fitting at the back of the carb is tight and not leaking air
You may have cause a leak of some kind when working on replacing the carb

I think that is your trans shift issue that you can fix and if so should not be a big problem to correct
Replacing all rubber hosee from one end of the car to the other is an important part of any restoration to keep the car road worthy


Just one hose back there from the brake system. Agreed that both brakes and trans are not functioning as before though I have a solid and tight connection behind the carb, just the same as it was on the Carter. Will have a closer look, though. Thanks!


What year and model Cadillac do you own ?

1964 CDV convertible. 


What you think is a brake line -( looks like one ) --is a vacuum line from the back of the carb down to the transmission shift Modual -- that is vacuum operated by the Carter or Edelbrock carb
Controls the transmissions shifting points
That must be air tight to work correctly

The trans will not shift well --if you are down two quarts of trans fluid so be sure you are topped off there
Check with engine at operating temp and engine running
The dip stick is calibrated in pints --so watch that

A beautiful white Convertible 64
I have the same car in Beacon Blue with the same wire hubcaps
Think the caps give the convertible a sportier look and set and it apart from others




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