1956 Holley carburetor vs Edelbrock

[Mr. Bill]

Want to replace a Holley carburetor should I replace with another Holley or go to a an Edelbrock ? What is the difference between the 2 brands? Which is better and more dependable?

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[biddle]

Title "1956 Thunder bird carburetor" is now "1956 Holley carburetor vs Edelbrock. Good titles get more responses.

PS no need to add "Tbird, Thunderbird" etc to subject line.

 

[Lionel]

Hi has anyone had any experience with edelbrock carburetor? We have a 465 cfm Holley on our 312 which is giving us a lot of problems. It floods regularly, it has been rebuilt a couple of times with new seals on the needle valve, new power valve and float levels set. Pump pressure is 5 psi. I’ve had it and considering changing to a new carb eg. a quick fuel 500 cfm or a edelbrock 500 cfm. I had no experience with edelbrock hence this post. Any suggestions would be appreciated. Lionel NZ

 

[1957Bird]

While the Edelbrock carb is overall a great carb, the problem with our early birds is that the stock ( oh so beautiful) air cleaner will not fit with the Edelbrock carb. It’s too high.
there is a company that is manufacturing a replacement intake $$$$$$ manifold that allows clearance but IMO just stick with a replacement Holley and have it professionally tuned once on the engine. That’s the route I went and have no regrets. Starts and runs like new and 14+ MPG.

 

[Lionel]

While the Edelbrock carb is overall a great carb, the problem with our early birds is that the stock ( oh so beautiful) air cleaner will not fit with the Edelbrock carb. It’s too high.
there is a company that is manufacturing a replacement intake $$$$$$ manifold that allows clearance but IMO just stick with a replacement Holley and have it professionally tuned once on the engine. That’s the route I went and have no regrets. Starts and runs like new and 14+ MPG.

Thanks very much I didn’t know the Edelbrock was higher. I think I will do the same and go for a Holley, what model and cfm did you use ?

 

[1957Bird]

I believe it’s a 4160 450CFM

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My 312 runs like a dream (after professional setup)
Absolutely no bog or stumble while still on choke smooth all the way through and effortless starting hot or cold.

 

[cscolastico]

When I purchased my 57 5 years ago it came with an Edlebrock. It's been running fantastically. I have a paper element air cleaner so that may be a mod the previous owner made to make it fit.

 

[1957Bird]

Interesting
I haven’t had any experience with putting an Edelbrock on the stock 312 manifold but everything I was told was that they were too high to allow use of original air cleaner,
But that certainly looks like it’s working

 

[Lionel]

When I purchased my 57 5 years ago it came with an Edlebrock. It's been running fantastically. I have a paper element air cleaner so that may be a mod the previous owner made to make it fit.
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That looks great thanks, are you running full vacuum advance at idle ?

 

[paul5456]

Mr Bill -what Holley do you have on it now? Is it the stock carb - a teapot? Changing the original carb to a later unit (either a Holley or an Edelbrock) will require an adapter for the intake manifold (or a 57 manifold) and a 57 or later distributor.

The Edelbrock is a very good carb, I run them on two cars and they ran very well out of the box. Don't really care for Holley's myself. With either carb, the stock 56 air cleaner will not work. A 57 will work on the Holley, some mods have to be made for the Edelbrock because of the right rear fuel inlet.

 

[74 Harley]

@Lionel, no carb/engine should be set up to have full vacuum at idle. You need to be running off of ported vacuum so that you have more vacuum with higher rpm.

 

[cscolastico]

That looks great thanks, are you running full vacuum advance at idle ?

Not sure. I know very little about carbs and since the car has been running great, I have not had the need to tinker with the carb or ignition. But I can tell you that the vacuum advance on the distributer is connected to the "left" vacuum port on the Edelbrock and I do have an Ignitor II under the distributor cap. Hope that helps.

 

[Lionel]

@Lionel, no carb/engine should be set up to have full vacuum at idle. You need to be running off of ported vacuum so that you have more vacuum with higher rpm.

Hi, I agree, I was curious because the Edelbrock has two vacuum ports according to the pictures of the installation instructions.

 

[Ward 57]

@Lionel, no carb/engine should be set up to have full vacuum at idle. You need to be running off of ported vacuum so that you have more vacuum with higher rpm.

If I understand the plumbing, you tune it so you have the most vacuum at idle. When accelerating the vacuum drops and that triggers the carb to add more fuel. I don't fully understand the vacuum advance on the distributor but I think it's designed to add more advance at low vacuum. That's why they added a vacuum pump to the fuel pump to keep the wipers working on acceleration. Ford loved vacuum systems well into the '60s until electrical servos were reliable.

 

[thessler]

I put on a Holly 390 cfm stock air filter, couldn't be happier.
Tom

 

[74 Harley]

@Ward57, the way a vacuum advance works is this way,
No vacuum is needed at idle.
The mechanical weights below the breaker plate advance timing with the greater rpm(until you reach max advance)
So say you're at a stoplight and nail it, this is where the vacuum advance takes over. The ported vacuum on the carb increase vacuum as the rpm rises. This in turn pulls the breaker plate to advance timing much faster than the mechanical weights. The result is more power off the line.
This is why you don't run off manifold vacuum. You would have full advance at idle and timing would retard under heavy throttle, until the mechanical advance could catch up.

 

[74 Harley]

Most carburators have multiple vacuum ports just because the manufacturers went vacuum happy with running accessories. Basically multi fit applications.

 

[Critterpainer]

I am read a bit of confusion here. Yes you tune for most vacuum at idle. What this means is that you install a vacuum gauge at a Manifold connection and set the IDLE mixture screws to the highest vacuum and then richen the mixture 1/8 turn (opinions may vary). The distributor vacuum goes to a ported tap on the carb. On most Holleys this is the line near top of the front fuel bowl on the passenger side of the car.

 

[Ward 57]

@Ward57, the way a vacuum advance works is this way,
No vacuum is needed at idle.
The mechanical weights below the breaker plate advance timing with the greater rpm(until you reach max advance)
So say you're at a stoplight and nail it, this is where the vacuum advance takes over. The ported vacuum on the carb increase vacuum as the rpm rises. This in turn pulls the breaker plate to advance timing much faster than the mechanical weights. The result is more power off the line.
This is why you don't run off manifold vacuum. You would have full advance at idle and timing would retard under heavy throttle, until the mechanical advance could catch up.

Gotcha, We are talking two vacuum sources. Carb & manifold. Carb vacuum for the distributor advance and manifold vacuum for other stuff.

 

[74 Harley]

Yes @Ward57, I think you have it.
@Critterpainer , well said.
And let me add that these systems are the same regardless of manufacturer, they all work the same.