I plan to do a full write up when this project is complete, however, I figured someone may get some benefit of seeing the progressions I make and the steps I took to get there. This also is a good way for me to keep notes on what I did and how I did it.
New Intake Purchased from Jason Edge and Painting the Intake
About a month ago, Jason reached out to me informing me that he had an intake that was in REALLY good shape. There had been some cracks on the underside of the exhaust crossover, but Jason informed me that the welds were really well done and that there is no issues with the integrity of the intake. As a plus, someone had already tapped and plugged the choke tubes. So this intake was the PERFECT candidate for a Carb Swap that I had been planning for some time. Not to mention, I got a SWEET deal on the intake and Jason also pulled an original A/C Fuel Bowl that my car was missing. So buying the intake and the fuel bowl led me down to just going ahead and tackling this project before summer get on its way. I want to make sure the top end of my car is TIP-TOP for cruising.
Jasons wife, Cheryl, was kind enough to bead blast the intake for me prior to shipping leaving me a clean slate to paint in preparation for the swap.
The intake arrived in a few days and I painted it with several coats of Bill Hirsch Cadillac Blue. This is some EXCELLENT paint. If you need the CORRECT color of paint, this is the stuff.
Research & Understanding
Admittedly, I should have done this FIRST, but I am an impulsive person.
I knew the basics behind this process, but I lacked an in depth understanding of exactly how all the parts worked together back in 1964 to make this carb heat/choke thing work.
So here is my best crack at it.
When the car is stone cold, the heat riser (located on the driver's side exhaust down pipe, just ahead of the Y pipe) is closed. The heat riser is a thermostatically controlled butterfly valve that opens and closes depending on how hot or cold it is. There is a bi-metallic spring that expands as it heats up and a weight attached to the butterfly and when the spring lets go and expands, the weight pulls the butterfly open and allows exhaust gasses to pass thru the pipe normally. However, when it's cold out, the car needs some heat. To accomplish this, that's when the valve is closed. It forces the driver's side exhaust gases back up THRU the heads and THRU the intake manifold and under the carb. This sufficiently warms everything up on those cold days. The choke tube are small ports inside the exhaust crossover pipes in the intake that actually run exhaust gas into the bottom side of the carb. If you plan to do a carb swap, you do not need or want this exhaust gas going into the manifold or under the carb as presumably, you will now have an electric choke
So, what do you do?
Well, here is what I am going to do.
Because my intake already has the choke tubes plugged, I don't have to worry about this, however, if you are going to SKIP a step, to my understanding, this would be one you could possibly skip to not cause any irreversible changes to your intake. Continue reading to understand why.
Because we no longer need the exhaust gasses to reach inside the intake or under the carb, why don't we block them at the source? Well, that's exactly what we'll do! If you read Jasons Carb Project, he used some thick roofing metal for the intake block off plates and an extra thick intake gasket, however, I will be using Olson Gaskets (Engine Gaskets for the Antique Market - Olson's Gaskets) that are made for Cadillacs specifically for this purpose. There is nothing wrong with doing it the other way, but these gaskets are cheap ($55 +S&H) and this just seems easier. So, I have those ordered as well and should be here soon.
So back to the choke tubes. To my understanding, you don't NEED to plug these if you are going to use the block off gaskets. However, you will need to inspect your intake. If the choke tubes are cracked or the crossover tubes in the intake are cracked, that is a HUGE intake leak that could cause severe issues. Its my recommendation that you block the choke tubes to be 100% safe and do it the right way, however, you may choose otherwise. For me, had my tube not already been plugged, I still would have done this regardless.
Some of you may also be wondering, OK, well, if the tubes are blocked, why change over the intake gaskets? Again, you wouldn't need to. But if continuing to run the stock carb, it'll run like garbage. Not to mention, the residual exhaust gasses would still be able to make their way to the intake, and it'll still be hotter than normal. Again, it is my recommendation that you block the choke tubes and the blocked off intake passages to do that job RIGHT.
And lastly, back to the heat riser. This is kind of the one thing that HAS to be removed. Did it serve a purpose 60 years ago? Yes. These were daily driver cars and people wanted them to function as such, however, these days, we don't need the car to warm up in 5 min. We can take time to let them warm gradually without all that excess heat entering the manifold. Plus, I don't know many people that driver their cars below 32 degrees anyhow. Not removing the riser will cause an extreme back pressure of exhaust gas until it warms and opens. Plus, if it ever fails, it'll fail closed. So, it's better remove and never think twice about it again.
I think all of that is fairly clear and concise and may help someone else understand the basics of this Carb Heat/Preheat system, naturally, let me know if you have questions!
New Carb
I was back on forth on which carb to purchase. Jason used an Edelbrock 1411, and I thought this would be a good candidate, however, as he notes in his write up, it was not a perfect fit. Using a 1411 required porting the primaries slightly larger to accept the higher flow (750 cfm) of the 1411 vs the lower flow (600 cfm) of the 1406. Being I have NO octane in my veins and a DEEP love for comfy cruising at 55-65 mph, I decided to stick with the 1406 for several reasons.
1) It was on sale at the time I purchased my unit. The 1411 was NOT on sale. I purchased through JEGS. They were the best deal and offered free shipping over $50, so that was a win-win.
2) Fuel Efficiency. From my understanding, the 1406 is tuned from factory to be more efficient on fuel. And into today's market, I'll save on fuel as much as I can. At the end of the day, that means I get to spend more miles behind the wheel for less money. Thats a win
3) Direct bolt up. I have NEVER done a carb swap and was not born into a family of hot rodders, while I have an inquisitive mind and can tinker till the cows come home, I prefer when things work and with the 1406, it should do just that!
I will note as well, if going to either the 1411 or the 1406, an adaptor ring will be required to use the stock air cleaner. I have no idea the sizes of the 1406 or the air cleaner or I'd list them here, I simply purchased the adaptor ring from Russ Austin. EZ PZ. I am sure you can use the chrome Edelbrock air cleaner as well; however, I want to stay as stock as possible.
What have I done so far?
Well, at this point, I have certainly only made things worse.
I got the car up on ramps and began the tedious process of trying to undo the Y pipe to remove the heat riser. The driver side actually wasnt too bad and loosened up right away with a little penetrating oil. However, there was not enough flex in the Y pipe for the riser to drop off the studs, so I attempted to loosen the passenger side manifold collector bolts. These were.... tight. And for some reason, much rustier. There wasn't enough room to get a wire brush in there, potentially that would have helped. I did use some heat, but the bolts were pretty far gone. I have not had a chance to REALLY inspect everything, but I am fairly certain I spun one of the nuts on the stud. The bottom nut tightened back up, but the top did not.
While I was able to get the heat riser out, before I can continue, I need to fix my oopsie.
Luckily, ACE Hardware had manifold studs. I purchased the few remaining that they had and hope they work, otherwise, it'll be back to the interwebs to find the correct studs. Lets just say, a Cadillac should NOT have straight pipes, erhm, well, no pipes at all. It sounds..... Not good with open headers.
Jason was able to confirm the size of the manifold studs as that info seems to be lost to time. I don't have the exact lengths, but they don't really matter as long as they are long ENOUGH and not too short.
The drivers side suds are longer by apprx 5/8" to make up for the riser and the threat pitch going INTO the manifold is 3/8"-16 (course) and the nut side that is exposed is 3/8"-24 (fine). I picked up a set of the combo thread studs and studs that are course on each side. I think I am going to go with course over course as that just seems easier. They were inexpensive and have another set if needed in the future.
I will take some tips on how to ensure these don't rust so bad for the future. I am thinking a coat of silver anti seize? Let me know if anything will help at all.
Parts Needed to Date:
I think thats all for now!
I am off to the garage to get the car on jack stands and begin my fight with the manifold studs-wish me luck!
05/01/2025
Tags:
Hi Logan,
You have done incredible work so far on this project!!!!!! Good luck with the studs - it is an arduous task. Take your time and pace yourself!
Dennis DiBari
You will need to fatten up the mixture on the rods. The car will run very lean and hot on the road. I usually go 2 steps up on the power and cruise chart.
This is the one part of this project I am concerned with. I ah e never adjusted a carb before. I did pick up a vacuum gauge and hoping to borrow a nice timing light. But as far as what’s too rich or too lean, that seems to be the hardest part for now.
Logan, changing out the metering rods or step up springs to adjust the fuel mixture is not that hard. The installation kit and included chart makes it easy to make slight changes to air/fuel mixture. What I would strongly suggest is installing the carb and getting the idle set and running the best you can out of the box, and driving it some to get a feel for how the carb is performing. Out of the box it may and probably will run pretty good... maybe better than you expect it. You may find some flat spots where it is too lean or where it bogs down, but I would strongly suggest giving yourself some time to run the carb before you start changing out stuff. In other words get the kit and know the changes you can make but dong get in too big of a hurry to start changing stuff.
I took a glance at the Help article I wrote many moons ago and it seems these are still current kits:
Fine Tuning the Carb using Calibration Kits (see picture 6 below)
Performance can often be tweaked by changing out the jets, metering rods and/or step-up springs. You can get calibration kits from Edelbrock that has an assortment of metering rods, jets, and step-up springs.
- The kit for the Edelbrock 1406 600cfm carb is the 1487 kit.
- The kit for the Edelbrock 1411 750cfm carb is the 1489 kit.
Jason-Thanks for the advice.
I have picked up the kit for the 1406 and I plan to have fun with this project and learn as I go! I am hopeful it is set fairly well out the of the box and expect it to run decently well! Time will tell!
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