The Stovebolt Site Forums The Shop Area Engine Shop carburetor spacer for a few horses - yes or no?

Looks like you can pick up approximately 6HP with a carb spacer, BUT, from what I've read, it can negatively impact low-end torque.

Anyone have thoughts on these?

Adding a spacer under the carburetor effective increases the plenum area of the intake manifold.

Obviously, the amount of increase depends on the thickness of the spacer.

The effect CAN be that the engine thinks it has a marginally larger carburetor, with an increase of a few percent (maybe 2~3 percent) AT WIDE OPEN THROTTLE MAXIMUM RPM!

If the carburetor is TOO SMALL for the engine, then the spacer will help.

If the carburetor is not too small, and some means are incorporated to require a larger carburetor (better cylinder head, camshaft, etc.) then the spacer may help.

Remember that too large a carburetor will have lower venturi air velocity, which CAN negatively effect low RPM performance.

But 6 HP on a 235??? I'm from Missouri!

Also, while a spacer CAN help with a hot soak condition with modern fuel ON A VEE engine, the same spacer MAY contribute to ICING ISSUES in high humidity and temperatures lower than 40 degrees on an inline engine.

If you are referring to the 350 in your signature, you MIGHT get 6 HP at WOT MAXIMUM RPM, but if the carburetor is correct for the engine?????

With the 350, unless you are trying to go very fast around slow corners; a better bet for usable horsepower AND low speed driveability would be a spread-bore intake and spread-bore carb such as the Rochester Q-Jet or Carter TQ instead of a square-bore. If you are racing road courses with SCCA, then the square-bore is easier to make go very fast around these corners.

Jon.

Thanks for the thoughts, Jon! I'm actually not looking to make my Panel a 10-second truck by any means I just wondered if a simple little bolt on like that was worth the effort.

Again, if this is a 350???, and you are having hot soak issues, then a non-metalic spacer might help with hot soak.

Jon

Yes, it's a 350 with an Edelbrock 1400 and Weiand aluminum intake.

While it would obviously be more difficult than simply bolting on a spacer, and also obviously more expensive; significant power, economy, AND driveability could be acquired by changing your intake/carb to a genuine Chevrolet 350 spread-bore intake, and either an original Chevrolet Rochester Q-Jet designed and calibrated for the 350, or the Carter aftermarket Chevrolet TQ.

Other than time and expense, the downside of this upgrade would be losing "cool points" at the car shows to the 16-year-olds.

Jon.

The engine that's in the truck now, came to me fully assembled, as a Craigslist special The original engine that was in the truck when I got it was also a 350, and when I tried to get it running, I quickly found out that it had more water in it than E deck of the Titanic..

I reached out on CL, and a guy nearby posted this other 350 for a good price. I threw it in the truck as-is. That's why it has quite a few oddball items on it

The 1400-series Performer carb should be good for even a mildly-build 350 engine without the need of a spacer. I have a crate 350 motor in my '60 Impala, bored .030 over, mild performance cam, and Edelbrock Performer series dual-plane intake manifold. When I purchased the Impala, it had a 1400 with manual choke (1405) which I converted to electric choke (1406) to improve driveability for my wife and daughters. (They still can't master the manual choke on my stovebolt!) My carb is calibrated to center-mass on the chart. I am quite happy with that setup...good economy and driveability, plus the ability to start a tire fire whenever I want!

I used an online calculator (there are several available), and with my displacement, at 6000 rpm (I don't want to rev higher!), and a volumetric efficiency of 85%, the carburetor CFM rating required is 524 CFM. For grins, I played around with the calculator a bit: If I rev to 6500 RPM and my intake/head combination attain 90% volumetric efficiency (!), it calculates to 600.9 CFM.

Carbking is way smarter than I, and may have other opinions...but... I don't think you're going to gain anything noticeable with a spacer. The largest gain will be to ensure your carb is in good condition, and calibrated properly (based on your application); rebuild kits and calibration kits are readily available, and not too expensive. Next would be ensuring the intake is optimized for the carb, engine, and application. I don't know anything about the Weiand intake, so I'm no help there.

-Kevin

approximately 6HP

Too bad Chevrolet never knew that...

Edelbrocks are poor quality clones of a Carter AFB. They make good paperweights if you use them right out of the box before they get installed on an engine. Once one's been run, the gasoline smell in a small office will give you headaches.
Jerry

I must have stumbled across an outlier Edelbrock then! This would be a great learning opportunity for those of us who don't have a broad base of experience. Please start a thread, and share the pros/cons of Carter versus Edelbrock.

-Kevin

A quick search of the forum archives will turn up several hours' worth of reading on the differences in AFB's and Edelbrocks. There's no sense beating that dead horse any more- - - -it's about as flat as a postage stamp already. Listen to Carb King, and pay close attention - - - - -he has far more knowledge on the subject than I do, and since he owns a lot of the original Carter manufacturing equipment and is in the business of making exact duplicates of their repair kits, I take his word as gospel. If anything, he has a lower opinion of Edelbrocks than I do.
Jerry

Jerry - I have given up on this subject, and you are right, that poor horse is dead, dead, dead.

Remember the movie "Field of Dreams"....................................."If you build it, they will come".

Well, paraphrase that with "if its cheap enough, someone will buy it".

The e-clones are, and forever will be, banned from our shop......no sales, no parts, no tech, nothing!

If someone is happy with theirs, great.

Jon.

Good morning pan31man,

As Jon points out not everyone is a fan of the Edelbrock carburetors:

"The e-clones are, and forever will be, banned from our shop......no sales, no parts, no tech, nothing!"

But as Jon has mentioned in the past the Edelbrock AFB clones do work out well for some of us. I have one on the sbc 350 engine in my street rod, a '32 Ford roadster. I got it as a #1405 and added an electric choke. Being familiar with jetting modifications to optimize performance and using a long, steep hill near my home as a dynomometer I experimented with primary and secondary jets and metering rods and found a combination that works well. This experimenting with the tune up also included trying various spark plug heat ranges and distributor initial timing, vacuum advance curves and centrifugal advance curves. Since it was a new engine build all of those variables had to be dealt with. But in the end my experience has been like Kevin's:

"The 1400-series Performer carb should be good for even a mildly-build 350 engine without the need of a spacer. I have a crate 350 motor in my '60 Impala, bored .030 over, mild performance cam, and Edelbrock Performer series dual-plane intake manifold. When I purchased the Impala, it had a 1400 with manual choke (1405) which I converted to electric choke (1406) to improve driveability for my wife and daughters."

There is hope for you based on our experiences. The real troublesome issue I had was with vapor lock that was severe on hot days in slow moving traffic. In an attempt to reduce heat input into the engine in general and fuel system in particular I added a fan shroud to the electric puller fan setup, put a thermal spacer between the carburetor and the Edelbrock Performer intake manifold, changed the fuel filter to one with a return port, put heat reflective sleeves over all the fuel lines, made a heat shield to reduce header heat input into the fuel pump and made ducting that feeds cool air to the air filter and carburetor. The cumulative effect of all that was to eliminate the vapor lock issue no matter how hot the day and how gridlocked the traffic.

You'll notice in the photos that this engine is not spotlessly clean. That's because the roadster is driven regularly and has accumulated nearly 25,000 miles during the last 17 years and at least this one Edelbrock AFB clone hasn't been touched since the original jetting was figured out.

Ray W

A plate of greasy scrambled eggs from the local Waffle House will keep me from starving to death, too, but I'd prefer to eat a good Denver omelet. The only thing they have in common is the eggs!
Jerry

The second priority for any business should be satisfied customers (or prospective customers). The first priority is surviving

Thus, for those of you that are satisfied with the clones, I am happy for you.

Jon.

"Thus, for those of you that are satisfied with the clones, I am happy for you."

Hi Jon. Happy Friday.

The only Edelbrock AFB clone I have any experience with is the one on my roadster engine. Until reading your many posts I had no idea that they can often be troublesome. I just jetted it for my newly built engine and ran it. I guess I got lucky because this one is on an engine that delivers good reliability, power and fuel economy. The only time I've touched the carburetor since jetting it so long ago was after the vapor lock problem was finally solved and I was able to reduce the idle speed because it no longer had a reduced idle speed and threatened to stall when vapor lock was about to occur. Now it has a steady idle speed under all conditions.

In the past you've explained that the AFB and Edelbrock clones use noticeably different metering rods. What other differences are there that would account for the performance differences? This subject is really interesting to me and apparently also to Kevin who states above "Please start a thread, and share the pros/cons of Carter versus Edelbrock." I looked at a lot of Amazon reviews of the 1406 and didn't find the answer there (84% 5-star and 9% 4-star ratings):

https://www.amazon.com/product-reviews/B000182DIS

To me learning new things is fun. In fact even at age 75 I believe that when we stop learning we stop living.

Thanks Jon!

Ray W

I've been really lucky with my Edelbrock then; I haven't had any vapor lock problems either.

When I bought my Impala, it had been sitting for a few years. One of the first things I did was to get a kit and rebuild the carb. I didn't have to change the calibration at all. It's been running great ever since. At this point, the only reason I'd ditch the Edelbrock would be to put an EFI system on it. I'll see how the EFI on my stovebolt goes first!

-Kevin

Not to poke the bear, but I had a clone carb on my 327 on my Chevelle that I bought new from Pep Girls, and it ran flawlessly from day 1 until I sold the car 10 yrs later. I also only drove the car to cruise nights and an occasional run at Cecil County Dragway

The 350 in my truck has the used 1400 on it that I mentioned before in this thread, and so far it's been OK. I did notice, though, that someone spun the electric choke cap so far counter clockwise that the chokeplate was always open, and the wire tabs were in the 12:00 position! No clue why, so I've adjusted it back to normal.

It's hard to imagine that a big company (Edelbrock) could buy the right to copy somebody else's highly evolved product (Carter's AFB), have a successful carburetor manufacturer (Weber) make the actual copies and end up with a lemon. Being a scientist (geologist) with a curious mind I wonder about the details of how that happened. I've asked on the Chevytalk forum what experiences people have had with the Edelbrock carburetors and so far there are only a couple of responses:

https://www.chevytalk.org/fusionbb/showtopic.php?tid/362448/post/new/#NEW

Jon really is the carburetor guru and I'm looking forward to more information on this topic.

The negative reviews on Amazon were for things like not including related hardware for installation on specific applications, like wires for the electric choke and a hold down stud for the air cleaner. Those negative comments surprised me because it's not possible to anticipate the details of every installation.

https://www.amazon.com/product-reviews/B000182DIS

When I built my roadster engine one of the Edelbrock heads I bought from Summit was full of aluminum chips from the machining process. I thought I was doing a good thing calling Edelbrock to report that quality control issue to them. The guy who took my call was outright nasty so I ended the call. Then I contacted Summit and they had a replacement head on my door step the next day along with a UPS call tag for returning the defective head without any unpleasantness. So maybe the problem has been with Edelbrock personnel, not their products. So far I don't know.

Ray W

NEVER underestimate the stupidity of a previous owner!

-Kevin

The person who answers the phone makes far less money than an engineer, knowledge in proportion.

The experiences that actual users of Performer AFB copies on this forum and on chevytalk have been positive:

https://www.chevytalk.org/fusionbb/showtopic.php?tid/362448/

Here's an example from chevytalk:

"I love my Edelbrock #1406 , been on my 56 Bel-air for about 17 years with NO problems at all.
I had it freshened up two years ago , not because it needed it but because I just wanted to keep running good without any problems."

I picked that example because he's had his for the exact same length of time I've had mine, 17 years, and in that extended period of time both his and mine worked perfectly and required no fixing. I did learn in private communication with Jon that as the AFB changed ownership from Carter to Federal Mogul to Edelbrock there was a modification in the accelerator pump system. But that and the differences in metering rods are the only differences I've been able to discover. Thanks Jon!

Ray W

So, the Edelbrocks are not merely clones of the Carter AFBs, but actually successors!

Good job researching Yar.

-Kevin

"Good job researching Yar."


Thanks Kevin.

I think the lesson learned is that information gained from independent research of a variety of sources is often different from information from a single source, no matter how supremely knowledgeable that single source claims to be. In the case of the Edelbrock carburetors it's simply not possible for a product to work well for so many people who took the time to post reviews and also not be a quality product.

Ray W