carburetor size on a 350

[Turbo4whl]

Sounds like this problem. “My significant other wants to jump my bones twice a day, you guys think that is too much”?

If you were closer I could help you with that issue.

 

[rt66paul]

A 780 CFM was stock on a Z28 302. I depends how built the engine is.

 

[JustJohn]

I like simplicity. My bone stock 350 Goodwrench crate engine runs just fine with a 600 cfm 1405/Performer dual plane Edelbrocks.

Same.

 

[MikeB]

Tell them the standard Quadrajet flows that much or more and stop talking to those people?

Yes, but the Q-jet primaries are tiny for great throttle response, and the secondaries open just enough the satisfy engine demand, which is not 100% open on a 350. That was the beauty of those carbs. You could probably put one on a 265 and it would work just fine running around on the tiny primaries, with the secondaries partially opening when needed. And then with some jetting changes, put it on a 400.

The Edelbrock 750 is a different animal. Its primaries are slightly smaller than the secondaries, but are larger than the Edelbrock 600 carb's primaries. So, the 600 will have crisper throttle response. That's a fact, Jack. And the 600's secondaries will probably never fully open, unless were talking about a 6,000 RPM engine with >90% VE. For reference, the 7,000 RPM 365hp/327 used a 585 CFM Holley, as did the base 390hp/427. It's simply a function of RPM, cubic inches, and VE.

That said, I think the new 650 Edlebrock AVS2 series would be my choice the the OP's engine. With its annular boosters and air valve adjustment it would blow away the antique 750 in every category. About that engine, what are the cam specs?

 

[Octane]

Yes, but the Q-jet primaries are tiny for great throttle response, and the secondaries open just enough the satisfy engine demand, which is not 100% open on a 350. That was the beauty of those carbs. You could probably put one on a 265 and it would work just fine running around on the tiny primaries, with the secondaries partially opening when needed. And then with some jetting changes, put it on a 400.

The Edelbrock 750 is a different animal. Its primaries are slightly smaller than the secondaries, but are larger than the Edelbrock 600 carb's primaries. So, the 600 will have crisper throttle response. That's a fact, Jack. And the 600's secondaries will probably never fully open, unless were talking about a 6,000 RPM engine with >90% VE. For reference, the 7,000 RPM 365hp/327 used a 585 CFM Holley, as did the base 390hp/427. It's simply a function of RPM, cubic inches, and VE.

That said, I think the new 650 Edlebrock AVS2 series would be my choice the the OP's engine. With its annular boosters and air valve adjustment it would blow away the antique 750 in every category. About that engine, what are the cam specs?

You speaking of primaries and secondaries etc, I had a Plymouth horizon with a holley carb on it back in the 1980s. I rebuilt it and somehow reversed the jets. It would bog down from zero to 30 and you couldn't hardly get it going but after you got up say past 30 mph it ran like a top from there on up to highway speed. I took it back apart seen what I had done. The smaller jet was the secondary and the larger jet was the primary, so when I had It reversed it couldn't get enough fuel to get started to speed.lol. I've done some carburetors from the '70s forward, mostly two barrels and that's the only one I ever screwed up on. I say it ran like a top when she got up to speed was a bit of an overstatement I should have said it ran better than it did starting off. Lol

 

[chevyninja350]

Thanks for all the help.

 

[chevyninja350]

I need help.
I know stock Chevy 350s are happy with 650 CFM carburetors. That being said I have a 750 Edelbrock 1411 on my non bored over 350 9.93:1 compression that is far from stock.

It has an Edelbrock dual-plane intake, A lopey 510/520 lift cam (2200-5800 RPM) and aftermarket vortec heads that I have ported and Polished myself.

Whenever I tell people I have a 750 CFM on a 350 they freak out saying my carburetor is too big but to me it doesn't feel like it's too big. When I stomp on the gas it does not bog it just goes, when I read my spark plugs either after daily driving it for a while or driving it hard the spark plugs look clean with light amount of soot around the ring at the end of the threads (in other words they look fine to me) and the vehicle idles fine. If this will tell you anything I have a vacuum reading between 15 and 16 inHg. I have not changed Jets metering rods or Springs.

When I tell people (including shop owners) that the engine runs fine. they say oh well it's still too big you're probably losing to tuneability or losing power at higher rpms.

So what I'm asking is is my carburetor too big, if not what defense can I use to make these people stop freaking out and what are the signs that a carburetor is too big?


1985 chevy c10 262 v6 swapped to around 400hp 350 vortec heads
Stage 3 700r4

Only a few people have partially answered my question. So here is a revision of my original post.

I want to use an Edelbrock/Carter AFB carburetor. For one reason or another I'm not interested in a Quadrajet, Holley or any other carburetor. I just want to keep the Edelbrock 4 barrel in mind for my question or questions rather.

My spark plugs look fine, The engine does not bog or stumble when I stomp on the gas. I am getting 15 to 16 inHg when I take a manifold vacuum reading.

Basically my questions were:
Given the information I have provided and the fact it seems to runs fine, Do you think my carburetor is too big, if not what defense can I use to make these people stop freaking out? If you do think it is to big, why is it to big and what disadvantages might it have to my setup? what are the signs that a carburetor is too big?

Here is refresher of my setup:
Chevy 350 not over bored
9.93:1 Compression
Edelbrock performer dual plane intake (7116)
Summit Racing Vortec heads that I ported and polished (sum-151124)
1.5 Roller rockers
Comp cams 510/520 lift, 282/288 (230/236 @.050) duration, 2200-5800 RPM, cam put in dot to dot.
PerTronix Flame-Thrower Hei distributor with 50,000 volt coil (D1051)

 

[idahovette]

#1 NO...#2 It runs too good to screw with....#3 NO..NOT TOO BIG..NONE....#4 You have no signs....DRIVE it, and tell the "freaks" to EF OFF!!!!!!

 

[chevyninja350]

#1 NO...#2 It runs too good to screw with....#3 NO..NOT TOO BIG..NONE....#4 You have no signs....DRIVE it, and tell the "freaks" to EF OFF!!!!!!

Pretty good reply LOL thanks

 

[SirRobyn0]

Yes, but the Q-jet primaries are tiny for great throttle response, and the secondaries open just enough the satisfy engine demand, which is not 100% open on a 350. That was the beauty of those carbs. You could probably put one on a 265 and it would work just fine running around on the tiny primaries, with the secondaries partially opening when needed. And then with some jetting changes, put it on a 400.

The Edelbrock 750 is a different animal. Its primaries are slightly smaller than the secondaries, but are larger than the Edelbrock 600 carb's primaries. So, the 600 will have crisper throttle response. That's a fact, Jack. And the 600's secondaries will probably never fully open, unless were talking about a 6,000 RPM engine with >90% VE. For reference, the 7,000 RPM 365hp/327 used a 585 CFM Holley, as did the base 390hp/427. It's simply a function of RPM, cubic inches, and VE.

That said, I think the new 650 Edlebrock AVS2 series would be my choice the the OP's engine. With its annular boosters and air valve adjustment it would blow away the antique 750 in every category. About that engine, what are the cam specs?

The above information is correct and I agree with all of it. I've done carburetor rebuilding as a professional, and I can not see why some folks don't like the Q-jet other than lack of understanding / complicated. Once setup properly it'll run more efficient and longer than any other carb. With that said there is nothing wrong with wanting a simpler / easier to adjust / tune carburetor if that's what you want.

Only a few people have partially answered my question. So here is a revision of my original post.

I want to use an Edelbrock/Carter AFB carburetor. For one reason or another I'm not interested in a Quadrajet, Holley or any other carburetor. I just want to keep the Edelbrock 4 barrel in mind for my question or questions rather.

My spark plugs look fine, The engine does not bog or stumble when I stomp on the gas. I am getting 15 to 16 inHg when I take a manifold vacuum reading.

Basically my questions were:
Given the information I have provided and the fact it seems to runs fine, Do you think my carburetor is too big, if not what defense can I use to make these people stop freaking out? If you do think it is to big, why is it to big and what disadvantages might it have to my setup? what are the signs that a carburetor is too big?

Here is refresher of my setup:
Chevy 350 not over bored
9.93:1 Compression
Edelbrock performer dual plane intake (7116)
Summit Racing Vortec heads that I ported and polished (sum-151124)
1.5 Roller rockers
Comp cams 510/520 lift, 282/288 (230/236 @.050) duration, 2200-5800 RPM, cam put in dot to dot.
PerTronix Flame-Thrower Hei distributor with 50,000 volt coil (D1051)

@chevyninja350 Looks like your fairly new around here, or at least to posting. Let me tell ya nothing will spark a hot debate like a carb question. So when you get folks that go off on one thing or another realize that's just the way it is here. Part of the reason I wrote so much about the Q-Jet is because the forum is viewable on the internet and someone might wander in and find it useful. I feel the need to speak of what I know.

I think I did answer your question in my first post, but encase I was not clear your setup is perfectly fine. No it's not the one I would choose, but the only problem you have it that some people keep telling you the carb is to big when you know it's not. The truck runs right, gets good mileage, why would you change it. No reason to. Enjoy it.

 

[Paladin]

WOW, all of that to fix a non-existing problem to keep people from "freaking out" over **** that doesn't concern them! Damn!!!

 

[82sbshortbed]

Yeah but, will it do a burnout?

 

[48hd]

got a 750 on mine

 

[75gmck25]

For the OP - I'll assume you are a relatively young guy who still cares about someone else "freaking out" about something on your vehicle. I think I'm way beyond that point.

As you get older you will realize there are all kinds of idiots and *ssholes out there, and most of them have no interest in doing more than just jerking your chain about something on your truck. They don't really have much expertise, so they just poke at you about details they think they understand. The same guys will freak out if you are running 2.73 gears or 4.56 gears, or using tires that are too big or small, or a 700R4 behind a high hp engine, etc. Its best to just ignore them, unless you really believe they have the expertise to make a useful contribution. Its your vehicle and you know your own priorities.

 

[Snoots]

A lot of what you hear are opinions. Like bungholes, everybody has them. Listen to everybody but pay attention to those that speak from personal experience.