carb choice ford bb
Senior User
Joined: Mar 2003
Posts: 195
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From: Mapleview,Mn.
ford carb
Sorry to disagree but the 4100 was the best carb made in its day,still is.Easy to rebuild and set up.Very simple operation.Made for the Ford Fe.
Your carb guy's are right 750 is to big for the 390.
Your carb guy's are right 750 is to big for the 390.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
ABTW he didn't say it was too big, he said it was almost too big. I'm not having any problems - except maybe with mileage - performance is outstanding. After two cars with quadrajets, I'm big on Carters anyway.
Postmaster
Joined: Mar 2000
Posts: 3,730
Likes: 13
From: Waynesville, OH
Julie (or anybody else), I have very little knowledge of carburetors, but I've always been curious about how to size them for any specific combination of CID, cam, etc. on a given motor. Have you had any issues with idling with your setup? For example, if you put it in gear and hold the brakes while letting the clutch grab just a little, do you find the engine starts to misfire?
The reason I ask is that, when I was a little bugger (we did our homework with chisels and stone slabs in those days
), I used to hang out at a tiny local garage that built the car Dan Caroll (sp?) drove on the NASCAR circuit. They had the usual big engine in there (don't remember the CID) and I believe a 1350 cfm Holley on top. The thing wouldn't idle below about 1000 RPM. Even at 1000 RPM, it was having a hard time drawing enough air through the carb to get some vacuum and pull gas through the fuel channels.
The reason I ask is that, when I was a little bugger (we did our homework with chisels and stone slabs in those days
), I used to hang out at a tiny local garage that built the car Dan Caroll (sp?) drove on the NASCAR circuit. They had the usual big engine in there (don't remember the CID) and I believe a 1350 cfm Holley on top. The thing wouldn't idle below about 1000 RPM. Even at 1000 RPM, it was having a hard time drawing enough air through the carb to get some vacuum and pull gas through the fuel channels.
Post Fiend
Joined: Feb 2001
Posts: 6,328
Likes: 124
From: Iowa
There are general guidelines for carb cfm vs CID, but it's definitely affected by the total combination. Flow cababilities of the heads and intake. Camshaft specs, rear engine gear ratio, vehicle weight etc. A spreadbore carb will allow you to run a large cfm carb with small carb characteristics at idle and cruise. Quadrajet is a good example of that. It is about almost 800cfm and GM put them on 305 CI engines for a decade.
A 650 cfm is a good street size for a 390 IMO, but a properly tuned 750 would also be fine.
A 650 cfm is a good street size for a 390 IMO, but a properly tuned 750 would also be fine.
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Joined: Oct 2009
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From: Burbank, WA
Julie (or anybody else), I have very little knowledge of carburetors, but I've always been curious about how to size them for any specific combination of CID, cam, etc. on a given motor. Have you had any issues with idling with your setup? For example, if you put it in gear and hold the brakes while letting the clutch grab just a little, do you find the engine starts to misfire?
The reason I ask is that, when I was a little bugger (we did our homework with chisels and stone slabs in those days), I used to hang out at a tiny local garage that built the car Dan Caroll (sp?) drove on the NASCAR circuit. They had the usual big engine in there (don't remember the CID) and I believe a 1350 cfm Holley on top. The thing wouldn't idle below about 1000 RPM. Even at 1000 RPM, it was having a hard time drawing enough air through the carb to get some vacuum and pull gas through the fuel channels.
The reason I ask is that, when I was a little bugger (we did our homework with chisels and stone slabs in those days
), I used to hang out at a tiny local garage that built the car Dan Caroll (sp?) drove on the NASCAR circuit. They had the usual big engine in there (don't remember the CID) and I believe a 1350 cfm Holley on top. The thing wouldn't idle below about 1000 RPM. Even at 1000 RPM, it was having a hard time drawing enough air through the carb to get some vacuum and pull gas through the fuel channels.
Mountain Pass
Joined: Dec 2009
Posts: 151
Likes: 44
From: El Reno Oklahoma
Speaking from personal experience w/ my 85 Bronco, 351w factory 4 bl intake and no performance mods. Bought the truck w/ the leaking Motorcraft {factoryholley?} carb, never could get it to run right. Replaced w/ a new electric choke 650 Holley. Hard to set-up correctly, always needed re-tuned every time the weather changed but was hands down the best performer running WOT. Last mod before selling the truck, mild RV cam new 650 Carter AFB and an Edelbrock performer intake. Starting, running, fuel economy, and overall drive-ability, as well as no leaks, vacuum or fuel, and as far as set it and forget it, was perfect. If there was a one-barrel version of that carb for my flathead I'd be all over it !
Logistics Pro
Joined: Feb 2005
Posts: 3,952
Likes: 117
From: Upper Left Coast
Howdy,
I would also suggest a 650.
I have one that I was going to put on my 292 but I'm being told it's a little "big" too!
It was on my OMC King Cobra 460. I Completely rebuilt it before removing and replacing the engine.
It's a 650 cfm Holley. It's what I would put on your engine.
If you want it, PM me.
Cheers,
Rick
I would also suggest a 650.
I have one that I was going to put on my 292 but I'm being told it's a little "big" too!
It was on my OMC King Cobra 460. I Completely rebuilt it before removing and replacing the engine.
It's a 650 cfm Holley. It's what I would put on your engine.
If you want it, PM me.
Cheers,
Rick
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