Best Carbs for Cammed 350

[alayna13]

Recently engine swapped my 85 C10, took out the stock 305 and put in a rebuilt 350 block with a massive cam and high compression pistons. Of course, my stock quadrajet off the 305 is too small now that she's pushing 300+hp (may seem small to some people on here but I'm excited!). Looking to upgrade, but the number of options and the things to look for are overwhelming so I'll take any suggestions.
Looking for around 700CFM but will take 650 or 750, electric choke, my current intake is spread bore but I can pick up an adapter easily. I was really looking into a Holley 0-80555C but can't seem to find one in stock anywhere.
Any help is appreciated!!

 

[hirschdalechevy]

What intake do you have now?

What are your cam spec's?

What is your compression?

I have used the spread bore holley's in the past, (0-6210), and they have worked very well for me but they don't have a lot of adjustability like the new holley style carbs. like quick fuel, brawler, holley hp, etc... So if you are into dialing in and messing with carbs you can only go so far with the 80555c with out doing mods to it. I am not bashing the 80555c but it cost's a lot for limited adjustability.

You really should pick a carb and intake for your cams torque range. If you want to keep your intake and are not into messing with carbs the 80555c would work well but a simi, q-jet, (sean murphy induction) or a jet, q-jet might be better being that they are all kind of higher dollar carbs like the 80555c holley.

Here are two holley's I am messing with right now, 600cfm 1850 with metering block conversion on the left and a quick fuel off road 600cfm with metering block conversion on the right.

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[Waylon]

I would look for an early electric choke Quadrajet from a 454. It would simplify installation if you still have your original intake, throttle cable and bracket. And it should be metered rich enough to get your new 350 close to optimal. If you get it tuned right, drivability will probably be better than anything else you might try.

 

[WebMonkey]

if it were mine, i'd have a rebuilt electric choke quadrajet on it.

it is more than capable of flowing what your motor specs require.

good luck!

 

[alayna13]

@hirshdalechevy

What intake do you have now?

What are your cam spec's?

What is your compression?

Thanks for the responses! Just the stock intake on it, factory off the 305. Unfortunately not sure about the cam's specs, it's a mild street cam, not super lopey but enough to bring the power up. The compression is 10:1. I get what you're saying about the adjustability of the 80555c, I definitely appreciate the advice since it's definitely quite a bit of money!

 

[alayna13]

I've thought about continuing with quadrajets, just got excited about possibly moving to a Holley or edelbrock but I appreciate the suggestions and will keep looking into it. Still got sometime before she's out of storage.

 

[hirschdalechevy]

@hirshdalechevy

What intake do you have now?

What are your cam spec's?

What is your compression?

Thanks for the responses! Just the stock intake on it, factory off the 305. Unfortunately not sure about the cam's specs, it's a mild street cam, not super lopey but enough to bring the power up. The compression is 10:1. I get what you're saying about the adjustability of the 80555c, I definitely appreciate the advice since it's definitely quite a bit of money!

Square bore G.M. performance, aluminum, high rise, dual plane, with a 1 inch open spacer.

215*@.050 int. / 223*@.050 exh. .473/.473 lift, 108 lsa. hydraulic roller cam.

9 to 1 compression.

vortec heads

If you want to keep the stock intake and you want some sort of mileage I would go with q-jet. However I would only go with s.m.i or jet , q-jets , not rebuilt (junk) q-jets.

If you like messing with carb's I would change the intake and go for a holley square bore, (might pull some more power out of it) if you are into that.

S.M.I. carb's you call them with your combo, elevation, compression, cam, etc... and they build you a q-jet.

I just put a new (brawler) 650cfm, double pumper, carb. on my engine for fun and it pulls harder than either carbs in the pic above.

I am no carb. expert, I just love playing with them to see if I can make them perfect.

So my next mission after I get the 650cfm brawler dialed in, is to keep toying with the two 600cfm vacuum secondary carb's to see if I can make them pull as hard as the brawler. Then I will keep the best one, (they are all new) and sell the other two. I might keep the quick fuel 600 off road one though because they dont make them anymore.

 

[82sbshortbed]

No way is the quadrajet "too small" for a 350. I had a 305 with a quadrajet I got from national carburetor. I bought a bbc 454 with an edelbrock 1407 on it with intake, rv cam and hedders.

The shop that swapped the motors told me I needed a bigger edelbrock carb on it. It was running OK but, was a bit sluggish.

I pulled the edelbrock carb off and put the quadrajet on with 3/4 adapter plate. It was night and day. Throttle response improved drastically. Tires break loose now when they wouldn't before.

I think the quadrajet is 750cfm. The back barrels are vacuum controlled so the more fuel the motor needs it will adjust. Plus call national carburetor and tell them what you have and if need be they can send you bigger jets for 20 bucks. They're really nice people and are willing to help you.

GM put those on for a reason. If it handles my 454 it will do fine for your 350. Jmo

Hope this helps

 

[SquareRoot]

EFI. Welcome to the 21st century.

 

[alayna13]

No way is the quadrajet "too small" for a 350. I had a 305 with a quadrajet I got from national carburetor. I bought a bbc 454 with an edelbrock 1407 on it with intake, rv cam and hedders.

The shop that swapped the motors told me I needed a bigger edelbrock carb on it. It was running OK but, was a bit sluggish.

I pulled the edelbrock carb off and put the quadrajet on with 3/4 adapter plate. It was night and day. Throttle response improved drastically. Tires break loose now when they wouldn't before.

I think the quadrajet is 750cfm. The back barrels are vacuum controlled so the more fuel the motor needs it will adjust. Plus call national carburetor and tell them what you have and if need be they can send you bigger jets for 20 bucks. They're really nice people and are willing to help you.

GM put those on for a reason. If it handles my 454 it will do fine for your 350. Jmo

Hope this helps

When I put the original carb from the 305 on the new engine it was backfiring through the carb, only ran when cold and would stall ou otherwise. Checked everything over a million times, the only thing left was that it wasn't getting enough fuel. Even set up an AFR to see if I could mess around and open up the jets more but it didn't work. Not entirely sure the carb was running as well as it could be anyways so I'm happy to get a new one for the new block.

 

[mcarlo86]

No way is the quadrajet "too small" for a 350. I had a 305 with a quadrajet I got from national carburetor. I bought a bbc 454 with an edelbrock 1407 on it with intake, rv cam and hedders.

The shop that swapped the motors told me I needed a bigger edelbrock carb on it. It was running OK but, was a bit sluggish.

I pulled the edelbrock carb off and put the quadrajet on with 3/4 adapter plate. It was night and day. Throttle response improved drastically. Tires break loose now when they wouldn't before.

I think the quadrajet is 750cfm. The back barrels are vacuum controlled so the more fuel the motor needs it will adjust. Plus call national carburetor and tell them what you have and if need be they can send you bigger jets for 20 bucks. They're really nice people and are willing to help you.

GM put those on for a reason. If it handles my 454 it will do fine for your 350. Jmo

Hope this helps

A good rebuilt Q-jet is really hard to beat. The small primaries are great for throttle response and like said earlier they are plenty "big enough" with those large vacuum secondaries. My 454 powered motorhome has a Q-jet and when you get your foot into it and those big secondaries open up, it really pulls. Sounds like the doghouse is going to get sucked into the air cleaner! haha.

 

[alayna13]

EFI. Welcome to the 21st century.

Send me the money for a swap and I will go right ahead lmao