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carburetor spacer for a few horses - yes or no?
#1375720 Thu Sep 03 2020 02:16 PM
Joined: Jan 2020
Posts: 160
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Shop Shark
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?


1957 Chevy Panel Truck, powered by SBC 350 from 1977 Camaro
Author, Bring CHANGE Into Your Life (a truly easy investment tool)
https://www.amazon.com/Bring-CHANGE-Into-truly-investment/dp/1077276869
Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375725 Thu Sep 03 2020 02:55 PM
Joined: Nov 2002
Posts: 2,067
C
Carburetion specialist
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! wink

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.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: carburetor spacer for a few horses - yes or no?
carbking #1375730 Thu Sep 03 2020 03:34 PM
Joined: Jan 2020
Posts: 160
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Thanks for the thoughts, Jon! I'm actually not looking to make my Panel a 10-second truck by any means smile I just wondered if a simple little bolt on like that was worth the effort.


1957 Chevy Panel Truck, powered by SBC 350 from 1977 Camaro
Author, Bring CHANGE Into Your Life (a truly easy investment tool)
https://www.amazon.com/Bring-CHANGE-Into-truly-investment/dp/1077276869
Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375734 Thu Sep 03 2020 04:13 PM
Joined: Nov 2002
Posts: 2,067
C
Carburetion specialist
Again, if this is a 350???, and you are having hot soak issues, then a non-metalic spacer might help with hot soak.

Jon


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: carburetor spacer for a few horses - yes or no?
carbking #1375736 Thu Sep 03 2020 04:25 PM
Joined: Jan 2020
Posts: 160
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Shop Shark
Yes, it's a 350 with an Edelbrock 1400 and Weiand aluminum intake.

Last edited by pan3lman; Thu Sep 03 2020 04:26 PM.

1957 Chevy Panel Truck, powered by SBC 350 from 1977 Camaro
Author, Bring CHANGE Into Your Life (a truly easy investment tool)
https://www.amazon.com/Bring-CHANGE-Into-truly-investment/dp/1077276869
Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375744 Thu Sep 03 2020 05:24 PM
Joined: Nov 2002
Posts: 2,067
C
Carburetion specialist
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.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: carburetor spacer for a few horses - yes or no?
carbking #1375750 Thu Sep 03 2020 06:04 PM
Joined: Jan 2020
Posts: 160
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Shop Shark
Originally Posted by carbking
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 smile 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 smile


1957 Chevy Panel Truck, powered by SBC 350 from 1977 Camaro
Author, Bring CHANGE Into Your Life (a truly easy investment tool)
https://www.amazon.com/Bring-CHANGE-Into-truly-investment/dp/1077276869
Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375790 Thu Sep 03 2020 08:38 PM
Joined: Mar 2019
Posts: 170
S
Shop Shark
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


This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375806 Thu Sep 03 2020 09:12 PM
Joined: Dec 2008
Posts: 1,484
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Shop Shark
approximately 6HP

Too bad Chevrolet never knew that...

Re: carburetor spacer for a few horses - yes or no?
pan3lman #1375810 Thu Sep 03 2020 09:58 PM
Joined: Feb 2004
Posts: 21,021
H
Boltergeist
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


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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