To much carb?
 

Does anyone think a 750 cfm Edelbrock carb is to much for a stock 350? Just wondering.

Re: To much carb?
 

Stock 350's come stock with a 750 cfm Quadrajet, although the secondary air flap came with different settings depending upon application........

So, NO! :D

Re: To much carb?
 

got a 750 Edelbrock on my ZZ6 works great

Re: To much carb?
 

I had a Holley 750 on my mild built 350 years ago.....switched to a 600 CFM Holley & it runs better & cleaner with more throttle response. Has a edelbrock performer intake and mild performance cam. Holley has a website with a carb calculator that you can put your engines info. in & it will tell you how much CFM you need for your application.

Re: To much carb?
 

A 600 or 650 vacuum secondary , would probably work better , If you had a holley 750 mechanical secondary , I would say , way too much

Re: To much carb?
 

I thank you very much guys.

Re: To much carb?
 

The holley 600 classic and the 670 avenger always run great on a stock to mildly built 350.

Re: To much carb?
 

I've got a 650 on my 454. Runs great...although I don't rev the snot out of it either. Most it sees is probably 3500- 4k rpm

Re: To much carb?
 

A general flat rule of thumb is 2cfm per cubic inch. All these cabs are in that realm.

Re: To much carb?
 

Never in my life have I heard that. By that reasoning I should have a 900cfm carb on my big block? Way too much fuel.

Re: To much carb?
 

Never had a 750 that worked well on the small block[Edelbrock that is] 600 seemed much better. On a big block however they seem fine. I need to point out I am a edelbrock fan it just seems to me that all the 750's on a small block the 600's just seemed smoother but that may have been in the tuning. I also had a 1050 Dominator on a bored out 402 that I could tap the throttle once hit the key and walk away and it would idle for hours without loading up Man I loved that carb

Re: To much carb?
 

I guess i remembered that wrong. I had an old performance expert tell me a ratio way back and it held true. Maybe it was 1.2:1 or 1.5, but forget all that. I know there is a formula, CFM = Cu In x RPM x Volumetric Efficiency (80%-90% normal w/race engines 95%-100+%) divided by 3,456.

Re: To much carb?
 

For a stock 350, yes! "Too much"

Re: To much carb?
 

If it has vacuum secondaries, it would probably work fine. It isn't ever going to really need that big of a carburetor though. But you'd probably get better response with a 600 cfm.

Re: To much carb?
 

This is only my experience without extensive knowledge, research or opinion. I replaced the quadrajet on my stock rebuilt 350 with an Edelbrock 1406 600cfm. It ran very rich to the point of pushing gas into the oil and soaking the plugs. Installed a low pressure fuel pump (not an Edelbrock) but very little improvement. Spent a weekend adjusting the timing and leaning it out as much as possible without changing the jets or rods. It slowed the soaking of the plugs and pushing fuel into the oil but still way too rich. Added fuel pressure gage and regulator down to 5.5 psi. Improved quite a bit but still not where I want it. Next is dropping one stage on the Edelbrock tuning grid by adjusting the rods and jets. If that doesn’t get it where I want, I’m going back to a quadrajet built by one of the well known rebuilders on the net.

As a point of reference I prefer drivability and MPG over performance. I’ve replaced the plug wires and plugs to stock. I tested the stock HEI coil and it’s good. Engine has good oil pressure and runs at normal operating temp.

Re: To much carb?
 

Best answer. The Quadrajet is the best all-around carb; the problem is that no new ones have been made for many years and the stock ones are worn out, particularly the throttle plate shafts. If you rebuild one the right way, you get an amazing carb that has small primaries for quick throttle response and good fuel economy, and large secondaries that will give you all the flow you need for almost any application.

Re: To much carb?
 

My $0.02 opinion that is too much. Most technically over carb but get away with it by using vacuum secondaries that are hardly used. Heck even a lowly 500 cfm carb on a stock to near stock 5500 rpm max 350 would be adequate 99% of the time and have better throttle response 100% of the time. It's all about the flow and speed of flow. A 600 cfm carb would be just fine leaving a little room to grow for better flowing intake, heads, and exhaust. Over cammed and over carb engines on an otherwise stock set up on the street are a dog to drive.

Re: To much carb?
 

And the spread bore (small primaries) is how 750 cfm can work well with 350 (more than 2 cfm:1 cu in) to 454.

Re: To much carb?
 

Right On.....99% of the time during everyday driving, your truck ( or car ) will never be in that RPM range. Way too many people overcarb then wonder why their engine runs like crap.

Re: To much carb?
 

I run an Edelbrock 1406 carb on my stock 350, it is a 600 cfm, with electric choke, i think, it is perfect , we run the same one on my son's trucks they are great, I have rebuilt one of them,because i got it used and it wasnt working correctly, they are sooo easy to rebuild

Re: To much carb?
 

I switched to a manual choke 1405. Very easy install and go. The more I played with it the better the truck ran. Keep in mind I am a daily driver with a 1 step over stock cam. Works perfect.

Added step up springs to the primaries to keep em closed longer, bravo Edelbrock Tech. Still have 22 inches of vac at idle on a very high mileage motor. Could fine tune some more as I have an adjustable advance to play with. It does hold the engine back under WOT which is just fine with me. The old Quadrajet might send that worn out bottom end to its demise.

600 cfm works for everyday, now when I build a mighty mouse things will be different esp. when I look into heads.

For stockers or mildly built they work! Even after 9 years of ethanol, quite well I may add.