Carb Size

[Lewis1129]

I’m doing a carb swap on my 91 tbi 350. I’m getting the parts together and have a question about carb size. I would like to put a 650 on it, but have access to a 3310 750 vacuum secondary Holley and also a 450 cam Holley. The truck is a daily and is stock for the moment. It will later get a mild cam. But that’s probably about it. Is the 450 going to be too small. And in the thought process will the 750 be too big.

 

[evilunclegrimace]

https://www.speedwaymotors.com/the-toolbox/what-size-carburetor-do-i-need/28634

 

[Redneckgeriatric]

450 best from your choices. do you know how to jet? a really cheap, easy to rebuild carb that would work great for you would be a 2bbl rochester from a 350 chevy. smooth idle and low end tq.

 

[PlayingWithTBI]

Here's another calculator you can use. As @Redneckgeriatric said the 450 is plenty for a stock 350 that shifts at ~4200RPM. Once you build it up and get up to 6000RPM then you'll want that 650CFM carb.
https://www.tciauto.com/racing-calculators

You can stick with TBI and go to a bored out (to 46mm) throttle body that'll support that...
https://www.ebay.com/itm/46mm-PORTE...837306?hash=item3d963196ba:g:mpwAAOSw2xRYWVJj

 

[kennythewelder]

650

 

[CRF450R]

Why in the hell would anyone convert from fuel injection to stone age crap CARBURETORS. Your best bet is to update to better more modern fuel injection do a LS swap and call it a day fuel injection = set it and forget carburetors = carberate it and allwas have to screw with it and even then it'll never run like fuel injection.

 

[PlayingWithTBI]

I agree about going backwards to the toilet bowl (AKA carburetor) fuel system but, that's an age old argument I don't want to get into. I was just giving some info on CFM requirements for a 350 Cu In, FYI, as I posted earlier, a bored out (to 46mm) TBI can give you 650CFM.

 

[89GMCJOHN]

I have run them all over the years .....a smaller carb on the street in a mild build always feels better .......FWIW.

 

[L29Sub]

Carbs would still be on most engines if not for EPA.
The only shortcoming is really cold weather cold starts. Beyond that, a properly set up carb is way too simple, starts better warm, and way too easy to repair (and cheap) if it dies. Daily drivers don't die often. FI is an 'engineers' toy. Especially on early GM SB and BB FI. I'm a Q'jet fan, but Holley can be setup to work as well. Try dx and repairing a BB FI out in the desert...[emoji15]


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[CRF450R]

Carbs would still be on most engines if not for EPA.
The only shortcoming is really cold weather cold starts. Beyond that, a properly set up carb is way too simple, starts better warm, and way too easy to repair (and cheap) if it dies. Daily drivers don't die often. FI is an 'engineers' toy. Especially on early GM SB and BB FI. I'm a Q'jet fan, but Holley can be setup to work as well. Try dx and repairing a BB FI out in the desert...[emoji15]


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You don't know **** about fuel injection carbs start better warm? Ya Oka carburetor fan boy carburetors suck **** it's 2020 get with times fuel injection is best well diesels are awesome aswell.No ****** way I could ever go from fuel injection back to a dam useless carburetor ever again I'd rather walk before going back to a pain in the ass carburetor!