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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Ignore the old write-up about plugging the 4 intake ports - 2 on top on exhaust channel and at each end of the internal choke tube.  All you need to do is block the large center exhaust port between the cylinder heads and the intake and make sure the heat riser butter fly stays open or has been removed on cold start-up. Here is the write-up you need to follow:

- Carburetor - Jason Edge Edelbrock 1406 & 1411 Installation Summary

So yes, I could do that, although it is once again a major assembly step I did not expect...but I'm not sure what is causing the big change in the brake pedal. It feels right now like changing back to Carter and phenolic spacer instead of Transdapt adapter will put everything the way it was, with safe brakes that feel right.

Carbguy did mine. I guess its not worth it for you as shipping will be high. But they are very good and do get repairs from all over Europe, but mostly from Sweden.

BTW, they are a lot better on carburetors than websites...

Yes, agreed, it is not difficult to get a professionally rebuilt Carter in the USA. This one says $200.  https://carburetorsandmore.com/index.php?main_page=index&cPath=18

Removing the intake to install 2 block plates is not a major step. Intake would have had to be removed to plug the bottom end choke tube port anyway if trying to install my "old way". I know the Edelbrock install steps have worked for numerous other contacts and customers, but it sounds like you have several other issues to deal with so perhaps getting back to factory setup and just making sure everything works as normal would be the best solution.

Two years ago I removed my Carter and had a professional company overhaul it. Costed about 500 USD and its been perfect since.

Not sure you want to pull the top of the engine apart - just to be blocking the heat passages of you Antique  Cadillac 

Could be something you —might consider —if and when you are into the engine for repairs that may be required in that area ( have the heads Redon )

i did very extensive heat reduction work on my race cars engine with excellent results and had the heat passages on it closed off but I have a need to keep my 429 the way Cadillac intended ( Edelbrock 1406 only )

Being a very performance minded person myself the stock 429 with the TH 400 trans behind it is one of the more enjoyable rides I have had the pleasure to own and drive 

Always a strong feeling of power and Torque and—- Torque can be an very addictive thing 

Why mess with perfection —is the way I evaluate this —engine trans combos performance 


Mostly concerned about the brakes and the fact that the trans does not SHIFT UP until a weird delay. Do not know why this carb change has affected so many things. 

The Edelbrock carbs come with the back vacuum port open. Did you install the included plug? If not, it will affect the vacuum/brakes/idle/performance.

Plug? No, I put the brake hose in there and clamped it down, just as it was with the Carter. So, there's only one port on the back, and I connected the brake hose to it, as before. 

Preston. That is correct. Simply remove the vacuum fitting from the back center of the old Carter AFB and install in the back of the Edelbrock and reconnect the power brake booster hose.  Almost everything on the Carter AFB to the Edelbrock is a simple switch over.  The exception vacuum-wise, is you will have 2 vacuum ports on the front of the carb for the vacuum advance... on ported and one full vacuum. One of those will need to be plugged...no other vacuum ports on the carb requires plugging.



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