GEEPAHOLIC
DASJEEP
- Location
- just north of south
what cfm carb would run good on a stock 77 chevy pu 4x4 auto with a 400 sb ?
GMC / Chevy carb ?
- Thread starter GEEPAHOLIC
- Start date
bobmed
- - - -
- Location
- sugarliberty
QUESTION How do I tell what size carb I need?
ANSWER You take the engine cubic inch and multiply by the maximum RPM and divide by 3456. If you have an automatic transmission you will need a vacuum sec. carb, a standard transmission can use a Double Pumper carb.
From Holley's web site
http://www.holley.com/TechService/FAQ.asp?category=Carburetor
ANSWER You take the engine cubic inch and multiply by the maximum RPM and divide by 3456. If you have an automatic transmission you will need a vacuum sec. carb, a standard transmission can use a Double Pumper carb.
From Holley's web site
http://www.holley.com/TechService/FAQ.asp?category=Carburetor
- Location
- Smithfield Utah
what cfm carb would run good on a stock 77 chevy pu 4x4 auto with a 400 sb ?
Whatever the cfm is for the stock Quadrajet that came on it
They are tough to beat imo anyway 
Whatever the cfm is for the stock Quadrajet that came on it
Wasnt that a 625cfm or so? This is sound advice.
Edit: Using the math, a 625 would be good to 5400 rpms on a 400
GEEPAHOLIC
DASJEEP
- Location
- just north of south
ok thankx to all . a little back story im looking a buying a truck its a 77 and it has a 400 sb in it with a holley card and it fouls plugs . carbon . so i was trying to find out what stock cfm was so i can look at the holley and se if its just to big or just needs a good tune or rejetting b4 i go buying a new 300 dollar carb for shits and giggles thankx i will update when i find out
- Location
- Grand Junction, CO
Holley's are good carbs in general, find out what model # it is and you'll learn quite a bit about what it is and if it will work for you. They're cheap & easy enough to rebuild too. If you're going to wheel the truck, I wouldn't run the Holley... unless it's the 'offroad' Avenger carb, since they're pretty good.
GEEPAHOLIC
DASJEEP
- Location
- just north of south
no plans for wheelin it for now im in north dakota working the truck will be just for erands and runnin aroumd town
cheepin
Active Member
- Location
- Parachute Co.
Just order a rebuilt Q-jet for that yr truck.Stock Q-jets are the best as far and power and fuel mileage goes.
Tacoma
Et incurventur ante non
- Location
- far enough away
If you've already got the carb on your truck, get one of the many books available on Holleys and tune that one.
If you're unhappy with it, junkyard a Q-Jet, which in my carb-hating opinion, is the best carb out there for offroading.... The Holley Truck Avenger is a good carb, but I still like the Q-Jets...
The one caveat with QJets is that they NEED TO BE TUNED PROPERLY, they are very precise by design. If they're not, they suck and you'll hate it.... and get a lame but easy Holley. : D
I LOVE fuel injection, but I really do like QJets
If you're unhappy with it, junkyard a Q-Jet, which in my carb-hating opinion, is the best carb out there for offroading.... The Holley Truck Avenger is a good carb, but I still like the Q-Jets...
The one caveat with QJets is that they NEED TO BE TUNED PROPERLY, they are very precise by design. If they're not, they suck and you'll hate it.... and get a lame but easy Holley. : D
I LOVE fuel injection, but I really do like QJets