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Discussion Starter · #1 · (Edited)
Anyone have experience with a custom carburetor? How much did you notice in performance? Good company to use? Why is it considered custom? I know it’s built around your specific set up, but what do they do that someone who can tune are carb can’t?

Trying to decide on a custom carb or going Holley EFI on a 93 pump gas 383 build.
 

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Discussion Starter · #3 ·
I honestly wasn’t referring to any specific company. I’ve read of people getting custom carbs specifically made for their set ups. I’m just curious if anyone has had experience with this and what kind of differences are made to make them “custom”?
 

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Just a personal opinion , there's a bunch of alleged " carb gurus" out there , there may even be some who have the expertise to actually effect positive changes . For your dollar , get a tunable e.f.i. , then you'll have a user friendly system that won't be built exclusively for one engine , a ballpark guess at the car bits its in , your driving habits , or one weather condition , plus , your new engine will probably last longer .( A result of not being " over fueled")
 

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The question really is: Will that custom carb be 100% right on the money for your engine/ vehicle combo? Doubt it. It will most likely be better then bolting on a new one out of the box ,but without spending some time tuning it won't be 100% correct. I agree with 2old2fast, If you don't have the know how to properly tune a carb then EFI is the way to go.
 

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You can just keep sending them money, or get some books and learn carburetor tuning yourself. They really aren’t all that complicated but are quite clever. Compared to EFI, including TBI, they really are quite primitive in how they operate it’s just using several types of vacuum sources that fall out of the gas laws see link Gas laws - Wikipedia

Not that I’m opposed to them, quite the opposite, they are relatively inexpensive and quite effective and for my own use are my go to preferred choice.

Remember the old saying that “most carburetor problems are electrical“ which pretty much means most of the problems attributed to carburetors originate within the ignition system and its tune. Like anything else this needs “a grain of salt“ be taken with it, but nonetheless has significant merit.

Bogie
 

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Discussion Starter · #7 ·
Thanks for the replies. Over the past year I have learned quite a bit tinkering with Holley, Q-jet and now Edelbrock. Over that time frame I’ve become pretty comfortable tuning them but I’m certainly no expert. I guess my question really is, how do they tune it better than anyone else that knows how to tune a carb, and it sounds like that answer is...they can’t.

My money will go towards an EFI at some point then, but until that point, I’m going keep having fun tuning on these carbs! I’m really enjoying it.
 

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It also depends on just how "custom" you get, most carb specialty builders have various different levels of modification.
The basic entry level carbs are just tuned up stock carbs, tuning anyone could do at home with either track testing, A/F meter, and plug reading along with careful record keeping to arrive at the correct tuning of the various circuits via air bleed, feed orifice, jetting, etc changes.

On a higher level carb build, each venturi gets flowed and hand reworked, booster gets tweaked to be exactly in the center of the venturi and exactly at the right height in vanturi for maximum signal response, the booster is often also hand reworked and refined on it's passage, disharge opening, underside lip, entry lip...or even replaced entirely with a different style booster, throttle shafts get thinned in profile, button head allen screws are used instead of the thick head stock brass screws, linkage is tweaked for secondary opening rate, and then here is the possibility of internal tweaking of metering block changes on Holley derived carbs.
A lot of this the average at home tuner has no ability to do, or lack the tools and fixturing to do the work.
 

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a racing carb from Willys or Braswell will race much better than a out of the box carb. I don't know what they do to them.
For street use, EFI is the only way to go now. I have no faith in how much alcohol might be in any particular pump gas, and carbs are stupid, they are just a controlled leak of fuel based on a pressure drop, they don't know that the gas has 5% alcohol or 19%.
 

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Custom Carbs.....
If you mean a professional carb builder with a good reputation and banks his livelyhood on it, then yes, you will get what you paid for. A carb that rivals FI in performance. Your gonna pay $1000-$1500 for one and custom tailored support. JDR, Stealth and Willys. I don’t like Brazwell at all. I have strong opinions on Brazwell and they aren’t good ones. The bottom line is they don’t drive like I want. There’s a distinct edge on fuel metering curves that compliment the entire engine program
If you mean a guy that knows how to put kits in them and can guess a jet range than no.
As Eric eluded too earlier, there’s about 200 ways to make a carb better. A few are not in the realm of a DIY’r such as booster modifications and individual Venturi flow as well as flow balancing. That’s very important to maximizing what it will do for you.
 

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Discussion Starter · #11 ·
You and Eric answered my question exactly. If there was a real difference in a custom tuned carb by a very reputable guy/company. I knew they would be pricey, but I was curious what the real difference is against a guy who can just tune a carb real well.

Im hoping this is the last engine I build for the truck. At least for a long time, and I like the idea of sticking with a carb versus going EFI. Then again, though, this is just a fun street driven truck. Maybe EFI is still the way to go solely due to they reason, but again, I like the idea of sticking with a carb for some reason. If I could get one custom made to the engine, especially if it would rival EFI in power/drive ability/fuel mileage, than the 1000-1500 price is about the same as an EFI set up.

Decisions, decisions!
 

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If you had a decent carb core, it would be considerably less. Somewhere in the $800 range. On my E85 engine, I have a QFT E85 on it. New out of the box it was $800, then I paid Mark Sullens to go over it. It’s even better than it was.
 

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Anyone have experience with a custom carburetor? How much did you notice in performance? Good company to use? Why is it considered custom? I know it’s built around your specific set up, but what do they do that someone who can tune are carb can’t?

Trying to decide on a custom carb or going Holley EFI on a 93 pump gas 383 build.
I have had excellent results from ProSystems Carbs, as have two of my friends. Beautiful response, right out of the box and not a lot more than an off the shelf HP Holley.
 

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I've spent a lot of time plaything with and modding carbs and I like them but I also like efi

In my opinion, part of the problem with carbs somewhat these days is modern pump gas is designed for high pressure injection(also emissions) and doesn't atomize as easy. Also why I like custom carb booster mods. Now I have never bought an entire custom carb but I've had a few mainbodies boosters modded and done other stuff myself. That said be careful who you have do the work, they may not do a very good job since your not buying an entire carb.
 

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I have had excellent results from ProSystems Carbs, as have two of my friends. Beautiful response, right out of the box and not a lot more than an off the shelf HP Holley.
Same with me. I sent Patrick all my engine information and he built me a carb that worked perfect right out of the box.
Another good guy to deal with is Mark Whitener from Lighting Racing Carbs. He is another one that can build you a good carb.
 

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I bought a carb from Pat at the carb shop and it worked out of the box. Ive changed jets for weather,,,

If your engine makes 500+ hp the buy a good fuel management system. If 450 hp then buy a good carb and learn to tune it. If it makes 400 hp then use w/e carb is cheapest
 
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