Go Back   MustangForums.com > Ford Mustang Tech > 5.0L (1979-1995) Mustang > Speed Density/Carb/SSP section
Sign in using an external account
Register Forgot Password?
Search


Speed Density/Carb/SSP section This section is for the Speed Density or Carb vehicles, as well as Special Service Package 'Stangs

Welcome to Mustang Forums!
Welcome to Mustang Forums.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


What size carb?

Reply
 
 
 
 
Thread Tools Search this Thread
Old 02-06-2009, 08:45 PM   #1
83ttopgt
2nd Gear Member
 
Join Date: Jul 2008
Location:
Posts: 195
Default What size carb?

I have a mostly stock 302, Longtube headers, Offenhauser intake, pretty lumpy cam (not sure of specs, but it idles like hell) dual exhaust. It has an Edelbrock 500 cfm on it right now, but I was told I should be running a larger carb.

Also the carb has had the choke butterfly removed. What is the advantage of removing it? The car came that way, and starts like $h** when cold, so I was considering replacing the missing parts, but wonder why they are missing in the first place
This ad is not displayed to registered or logged-in members.
Register your free account today and become a member on Mustang Forums!
__________________
1967 289 coupe. Was my dads
83ttopgt is offline   Reply With Quote
Old 02-07-2009, 07:11 PM   #2
ACE
4th Gear Member
 
Join Date: Jul 2005
Vehicle: 90 notch
Location:
Posts: 1,209
Send a message via AIM to ACE
Default

someone who was bored decided to take them out haha. My best suggestion is to get a holley 600 vacuum secondary carb with an electric choke.
__________________

Windsor powah!
1985 GT 1986 GT sunroof 1986 GT T-top 90 notch and a side of a yellow vert
ACE is offline   Reply With Quote
Old 02-07-2009, 08:14 PM   #3
wildcobrar
3rd Gear Member
 
Join Date: Aug 2005
Vehicle: 1990 Mustang Hatch LX
Location:
Posts: 577
Default

I would go 650 Double pump holley. That carb will grow with your combo somewhat if you choose to go better heads and such. Also it can be bumped to a 750 HP style holley carb if you need more carb just by changing the center body.

Joe
__________________
Always in search of faster ET. Helpfull Home: http://www.toonutsracing.com/smf/index.php
wildcobrar is offline   Reply With Quote
Old 02-08-2009, 10:15 PM   #4
my77stang
6th Gear Member
 
my77stang's Avatar
 
Join Date: Dec 2006
Vehicle: 77 II, 06 GT
Location: Citrus County, FL
Posts: 8,007
Send a message via AIM to my77stang Send a message via MSN to my77stang Send a message via Yahoo to my77stang
Default

Quote:
someone who was bored decided to take them out haha. My best suggestion is to get a holley 600 vacuum secondary carb with an electric choke.
^ thats the winning post. i chopped my choke horn off of my 600 and gained a bump in power for sure, but it sure is a hard starter when cold even in florida.

Click the image to open in full size.
__________________
“‎Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see.” - Thomas Jefferson
my77stang is offline   Reply With Quote
Old 02-09-2009, 11:18 AM   #5
83ttopgt
2nd Gear Member
 
Join Date: Jul 2008
Location:
Posts: 195
Default

so the choke was pulled to "cover" the small carb prob. I should just get a bigger one that will grow with my motor? What size is recommended for a 347 build? would this size carb be too big for a 302?
__________________
1967 289 coupe. Was my dads
83ttopgt is offline   Reply With Quote
Old 02-09-2009, 01:26 PM   #6
my77stang
6th Gear Member
 
my77stang's Avatar
 
Join Date: Dec 2006
Vehicle: 77 II, 06 GT
Location: Citrus County, FL
Posts: 8,007
Send a message via AIM to my77stang Send a message via MSN to my77stang Send a message via Yahoo to my77stang
Default

a 650 is too big for a 302 unless its very radical, but would be a great fit on a 347. if your dead set on going bigger on your 302, look at a 650 vacuum secondary carb not a double pumper.

i removed my choke tower because of the air flow restriction the choke tower has, especially when you have a thin air cleaner assembly.

see?
Click the image to open in full size.
__________________
“‎Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see.” - Thomas Jefferson
my77stang is offline   Reply With Quote
Old 02-09-2009, 02:21 PM   #7
wildcobrar
3rd Gear Member
 
Join Date: Aug 2005
Vehicle: 1990 Mustang Hatch LX
Location:
Posts: 577
Default

Something to think about. Take a 302 with a single plane intake and place a 600 cfm carb on it. Take same 302 and place a dual plane intake on it with a 650 double pump carb. Which engine sees "more carb" at the cylinder?



Dual plane intake takes a carb an divides it in half.

I built a 306 inch 302 with a Ford Racing flat hydraulic cam(220/230@.050 .496 and .509 lift) and home ported D2/D3 heads. Performer RPM intake and less than ideal headers. Dura spark ignition 100 GPH mechanical fuel pump with 9.0 to 1 compression. It had less than ideal 2 inch exhaust. 3.73 rear gears and a T 5 transmission. It was all just junk that had been collecting dust in the shop. Car with driver came in a 3050 pounds. It6 had a 600 VS Holley but felt like it wanted more Carb. So off went the 600 and on went a 750 HP Holley carb. It picked up 4 10ths in the 1/4 mile. Car ran a best of 12.54 @ 108 on engine with 26 inch slicks.

I don't think a 650 to 750 is too big for a 302. Why run the risk of choking an engine when you can go to the high side and tune it to what it likes vs having to just accept the 600 as a bad choice if it turns out to be a choke point on the engine?

An added advantage to a 650 Double pump is it shares the same throttle base plate as a 750 Double pump. When the engine needs to see more carb, the 650 can be bumped to a 750(HP style at that) for about $109.00 bucks. Again an added value and advantage to using a 650 Double Pump holley carb.


Joe
__________________
Always in search of faster ET. Helpfull Home: http://www.toonutsracing.com/smf/index.php
wildcobrar is offline   Reply With Quote
Old 02-09-2009, 08:37 PM   #8
83ttopgt
2nd Gear Member
 
Join Date: Jul 2008
Location:
Posts: 195
Default

so I found an edelbrock 650 locally with vacuum secondaries and electric choke. Would this be a good choice?
__________________
1967 289 coupe. Was my dads
83ttopgt is offline   Reply With Quote
Old 02-10-2009, 06:39 AM   #9
wildcobrar
3rd Gear Member
 
Join Date: Aug 2005
Vehicle: 1990 Mustang Hatch LX
Location:
Posts: 577
Default

Quote:
Originally Posted by 83ttopgt View Post
so I found an edelbrock 650 locally with vacuum secondaries and electric choke. Would this be a good choice?

It is ok, but the 650 Holley can be upgraded at little expense to a 750 HP Holley style carb when your project grows performance wise. I have messed around with both makes of carbs and I give the Holley the edge in performance and ease for tuning. There are many books out there as well that will help you learn how to repair/tune a holley.

Joe
__________________
Always in search of faster ET. Helpfull Home: http://www.toonutsracing.com/smf/index.php
wildcobrar is offline   Reply With Quote
Old 02-10-2009, 11:13 AM   #10
83ttopgt
2nd Gear Member
 
Join Date: Jul 2008
Location:
Posts: 195
Default

I eventually want to run a big holley, but I am going to build my stroker motor first. In the mean time will the edelbrock 650 be ok for the summer? I am more of a holley fan, but I can get the edelbrock cheap, and its in good working order, I can hear it on the car running
__________________
1967 289 coupe. Was my dads
83ttopgt is offline   Reply With Quote
Old 02-10-2009, 01:33 PM   #11
wildcobrar
3rd Gear Member
 
Join Date: Aug 2005
Vehicle: 1990 Mustang Hatch LX
Location:
Posts: 577
Default

Quote:
Originally Posted by 83ttopgt View Post
I eventually want to run a big holley, but I am going to build my stroker motor first. In the mean time will the edelbrock 650 be ok for the summer? I am more of a holley fan, but I can get the edelbrock cheap, and its in good working order, I can hear it on the car running
Go for it, then just sell it for what you feel it is worth when you are done and flip the cash over into the holley. In the end as long as you are happy with it, that is all that matters.

Joe
__________________
Always in search of faster ET. Helpfull Home: http://www.toonutsracing.com/smf/index.php
wildcobrar is offline   Reply With Quote
Old 02-10-2009, 11:13 PM   #12
my77stang
6th Gear Member
 
my77stang's Avatar
 
Join Date: Dec 2006
Vehicle: 77 II, 06 GT
Location: Citrus County, FL
Posts: 8,007
Send a message via AIM to my77stang Send a message via MSN to my77stang Send a message via Yahoo to my77stang
Default

this whole thread fails
__________________
“‎Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see.” - Thomas Jefferson
my77stang is offline   Reply With Quote
Old 02-11-2009, 08:50 PM   #13
Joel5.0
5th Gear Member
 
Joel5.0's Avatar
 
Join Date: Jan 2006
Vehicle: 1986 Ford Mustang GT
Location: Puerto Rico
Posts: 3,926
Default

Quote:
Originally Posted by my77stang View Post
a 650 is too big for a 302 unless its very radical, but would be a great fit on a 347.
Why?..... like wildcobrar, my experience with my junk over the years, and the '85 with a B-303 and 750 cfm Holley customer I had to work on last week..... 650 cfm carb is not too big for a 302.
__________________
ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***

1986 GT-X303-289 heads-1.72 rockers-RG 4+1 Trans.
Quote:
Originally Posted by Joel5.0
Great thoughts will overwhelm a feeble mind.
There is never money to do it right, but there's always money to do it over.
The proof of understanding is the ability to explain it. (H. Torruella)
Joel5.0 is offline   Reply With Quote
Old 02-13-2009, 08:26 AM   #14
wildcobrar
3rd Gear Member
 
Join Date: Aug 2005
Vehicle: 1990 Mustang Hatch LX
Location:
Posts: 577
Default

Quote:
Originally Posted by Joel5.0 View Post
Why?..... like wildcobrar, my experience with my junk over the years, and the '85 with a B-303 and 750 cfm Holley customer I had to work on last week..... 650 cfm carb is not too big for a 302.

I agree Joel5.0. Did Ford not put a 780CFM double pump carb on a 1970 302 Mustang that had 290/300 HP? I mean I have an 850 Double Pump Holley on my 351 inch pump gas street car. Car works ok, maybe it has too much carb????? Oh and the most recent build I did for a street/strip car for one of my clients was speced out by Patrick@Pro Systems. 393 Windsor on pump gas with a 950HP Pro Systems carb in a street Mustang. Given Patrick is a very big Player in the Horse Power Game I am not going to question or Doubt him!


Joe
__________________
Always in search of faster ET. Helpfull Home: http://www.toonutsracing.com/smf/index.php
wildcobrar is offline   Reply With Quote
Old 02-13-2009, 09:28 AM   #15
Portmaster
5th Gear Member
 
Portmaster's Avatar
 
Join Date: Nov 2008
Vehicle: 1985 LX Coupe
Location: SC
Posts: 2,401
Default

Quote:
Originally Posted by wildcobrar View Post
I agree Joel5.0. Did Ford not put a 780CFM double pump carb on a 1970 302 Mustang that had 290/300 HP?


Joe
First of all you are talking apple and oranges. The 290HP 302 in 1970 was the BOSS 302. The HP rating was a joke and if you removed the factory rev limiter that engine would spin up past 8000 rpm. The carb wasn't a Holley 780 Double Pumper. It was a Holley 780 Vac Secondary. The Boss 302 with the rev limiter in place would put out a minimum of 350 hp. Unleashed the Boss 302 would jump up well past 400 hp. The 290hp rating was just to get past high insurance cost. Back in the muscle car days HP ratings were just something to help the buyers. An Example was the Chevy L-88 427. It was rated at 430hp. Actual hp was over 550hp.

You CAN over carb an engine. While performance may be acceptable with a larger carb and it can leave you room to grow IF that is what your intentions are it's a fact that a properly sized carb for your application will perform better across the entire rpm range . A larger carb may make a few more peak hp but you have to ask yourself how often is your car at wide open throttle. There is a a certain point to where a carb becomes so large that peak power and overall torque will suffer. Most mildly built 302's will perform to their peak with a 600 cfm vac secondary carb and give you the best OVERALL performance.
__________________
making engines breath since 1968

1985 LX Coupe, 347/581hp N/A TCI C6 Currie 9 inch 4:10s 2577 pounds. Do the math
Portmaster is offline   Reply With Quote
Old 02-16-2009, 07:50 PM   #16
Joel5.0
5th Gear Member
 
Joel5.0's Avatar
 
Join Date: Jan 2006
Vehicle: 1986 Ford Mustang GT
Location: Puerto Rico
Posts: 3,926
Default

The Holley 4180 (B5ZE-9510-GA), the emissions based Holley in stock '83-'85 Mustangs, is rated at ~580 cfm. Mr. Carrol Shelby used a Holley 715 cfm carburetor in the GT350 289 CID setup... and during my first days with the gang, we would look for 428 SCJ Holley's (735 cfm) for our street 289/302 setups. A carburetor is a tunable A/F providing device, and those 715 and 735 carburetors really worked.

A carburetor is an intake restriction by design, that's the way they work..... but you have to make sure the engine is able to breath when required, and the carburetor capable of supplying that A/F as needed. A 650 or 750 cfm Holley, is not too big of a carburetor for a 302.
__________________
ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***

1986 GT-X303-289 heads-1.72 rockers-RG 4+1 Trans.
Quote:
Originally Posted by Joel5.0
Great thoughts will overwhelm a feeble mind.
There is never money to do it right, but there's always money to do it over.
The proof of understanding is the ability to explain it. (H. Torruella)
Joel5.0 is offline   Reply With Quote
Old 03-03-2009, 12:53 PM   #17
mstngsule68
4th Gear Member
 
Join Date: Apr 2008
Location: milwaukee NOT THE GHETTO PART
Posts: 1,025
Default

i had a 780holley on a h/c/i exhaust and other stuff on a 289.
__________________


http://mustangforums.com/forum/wisco...l-chapter-150/
'87 stang with some goodies on it----sold
'68 stang being restored ~finally after 6years its coming together~
'05 torch red/coupe
"Even one weakpoint, is STILL a weakpoint. Don't make any"
mstngsule68 is offline   Reply With Quote
Old 03-03-2009, 05:13 PM   #18
Portmaster
5th Gear Member
 
Portmaster's Avatar
 
Join Date: Nov 2008
Vehicle: 1985 LX Coupe
Location: SC
Posts: 2,401
Default

I had a 780 Nascar Holley off a 406 Ford Galaxie (406 was a runner) on my 65 289 2+2 Mustang back in the 60's. It ran great, no issues. It was quicker with an 600 cfm. A bigger carb will run OK but a properly sized carb runs better. Every engine is differant and some will respond to more carb than others.
__________________
making engines breath since 1968

1985 LX Coupe, 347/581hp N/A TCI C6 Currie 9 inch 4:10s 2577 pounds. Do the math
Portmaster is offline   Reply With Quote
Old 03-03-2009, 05:13 PM
MustangForums
Ford Mustang




Paid Advertisement

 
 
 
Reply

Tags
302, 306, 347, 50, 650, 750, big, carb, carburetor, double, edelbrock, ford, holley, pump, size, wildcobrar

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What size carb would you run on it? slickman Classic Mustangs (Tech) 35 08-29-2006 10:33 PM

Advertising

Featured Sponsors
Vendor Directory
New Sponsors
All times are GMT -5. The time now is 09:37 PM.

© Internet Brands, Inc.


This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company
Emails Backup