CARBURATOR WAR!!!!!!!!!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mark25 · 03-24-2002, 08:56 PM

my 670 Holley street avenger is about to get the best of me!!! thinking of switching to a 750 Carter AFB manual choke. this is on a healthy 350, 380 horse/385 torque, 10.25 compression, with a Comp Cam 280H (480 lift, 280 duration, 230@.050, 110 lobe seperation).
if you run my engine through carb formula (cubic inches x max RPM / 3456) i get 616 cfm needed to run motor plus holley/summitt says add another 20% for performance which brings me to 739 cfm carb. could a 750 live on this motor and not be too much carb. have seen a few guys on this board that said the 750 is a little overkill. what do i do????? HELP!!!!!!!!

Longhorn Man · 03-24-2002, 09:10 PM

Go for the 750. Even a stock one will nomally benifit from a 750 over a 600. Formulas be damned, it always seems to be true.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
Need to pick up the one ton Longhorn with a PONTIAC 350/350soon.
Thanks every one!

Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

Brad69 · 03-24-2002, 09:13 PM

Holley's website says to use the 670 for stage 1 engines, and go one size up for stage 2 or 3. They define stage 1 as carb/manifold/headers, stage 2 as adding a cam, stage 3 as ported heads.

bigjimzlll · 03-24-2002, 09:51 PM

hey mark...thats just about the same set ill be running...hows that 280H? do u still have plenty of low end torque? what kind of trans and rear do u have?

sam's 72 · 03-24-2002, 10:48 PM

YES THE 750 WILL WORK, I wouldn't go to much more though
sam

704x4 · 03-25-2002, 10:11 PM

bigger isn't always better i have a 370horse/355 that i never got to run right with a 750 edelbrock(carter).

i had a hell of a hesitation off idle so bad it would die every once in a while

i sold the 750 and bought a 600 and i have never had a better running small block

the 750 was a waste of time and money, call the edelbrock tech line at 1-800-416-8628 and have all of your engine info ready(be prepared to wait 20 mins) they will tell you exactly what you need.

just didnt want you to go through what i did

Longhorn Man · 03-25-2002, 10:20 PM

If you ain't happy with a 750...I'll trade you for my new Eldebrock 600.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
Need to pick up the one ton Longhorn with a PONTIAC 350/350soon.
Thanks every one!

Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

raychevy · 03-25-2002, 10:34 PM

On my stock 350 it had a 750 edelbrock. Too much fuel if you ask me. If I gave the truck more than 45 percent throttle, nothing but black smoke from the rear. I could accelerate faster at 45 percent than more pedal because it would pour fuel down it. Gas could come out the tailpipe sometimes.

Sinister · 03-27-2002, 12:02 AM

ya gotta give the motor what it wants...
primary jetting, metering rods etc. all come into play...
i had a 1407 edelbrock in my'72 c-20...
looked nice, ran straight out of the box...
but it didn't run as well as my Quadrajet
cause i didn't feel like tuning it...

check out: http://www.montecarloss.com/technical.html#Induction

guypm · 03-27-2002, 04:53 PM

ive got a 750 holley double-pumper on mine and i absolutely fricken luv it. im running a 280h comp cam,700r4,3:73 rear(open and would rather a posi...need $$$)performer rpm heads, roller rockers,performer rpm intake.
try it you'll like it too.
Guy

Stepside · 03-27-2002, 07:06 PM

670 is plenty. Lean is horsepower... to a point. Is it misfiring? Does it get hot at idle? If not, you're not too lean. Read the plugs. Here's what I have in my 70:
355 CI, 10.25/1 flat tops
461 Double Hump heads (64 cc). Fully ported (by a NASCAR Modified engine builder)
501/292 Cam
70 Z-28 LT1 Dual Plane intake
650 (4777) Holley (I haven't bought a new one since 1984)
You have to study about Holleys. I've had 750's, 780's.,850's, and even a 600 on my truck. The 650, with some tuning, screams. I got all the other carbs running fine... even the 600. Had to put 780 metering blocks on the back side. Great gas milage. But ran hot at idle. I put a 650 base plate on it solved that, with a little idle circuit porting. What I'm saying is, if you want all the power your motor can give, "build" a Holley. If you want a maintenance free carb, "buy" one of the AFB styles. Sorry for rambling

------------------
70 sstep tubbed, Muncie
68 swb LT-1

704x4 · 03-27-2002, 10:58 PM

raychevy

thanks for not talking out your a##, and not giving this guy advice that he doesn't need.

i hate to say it but it doesn't impress me when someone says that they have a big carb infact if most people understood how a carb works (not saying i'm an expert) they would know that there is such thing as too big of a carb, too much fuel, and running too rich.

often the symptoms blammed on lean conditions are the exact opposite!

Longhorn Man · 03-27-2002, 11:05 PM

'70, you are right, but I have never seen a 350 that has any performance parts on it not react favorably to a 750.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
Need to pick up the one ton Longhorn with a PONTIAC 350/350soon.
Thanks every one!

Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

704x4 · 03-27-2002, 11:30 PM

mail
thankyou for the response i was just speaking from experience i have had, and i thought it would help the guy out

it was too much for my 355 it ran way to rich i even tried to recalibrate it.

then after i talked to edelbrock the told me it was too much

performor intake
crane roller rockers 1.5:1
sportsmanII 64cc angled plug heads 2.02/1.60
9.5 to 1 compression
flat top pistons
comp cam 12-231-2
hooker headers

i wasn't getting on your case, i just hear the big carb thing too much. sorry

Longhorn Man · 03-27-2002, 11:40 PM

I know what your saying man. no harm done.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
Need to pick up the one ton Longhorn with a PONTIAC 350/350soon.
Thanks every one!

Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

aesj2 · 03-28-2002, 02:14 AM

Just use a BB Q-Jet. It will flow 780 cfm and get better mpg on the highway.

**DANTIP** · 03-28-2002, 09:16 AM

I HAVE HAD EXCELLENT RESULTS FROM A EDELBROCK 600 W/ELECTRIC CHOKE ON MY ZZ3 350 (345 HP). GREAT THROTTLE RESPONSE, EASY STARTING, NO SMOKE, AND GOOD FUEL ECONOMY.

**70cst** · 03-28-2002, 03:47 PM

I'm about to purchase a Holley Avenger 770 for my 70cst. The truck has a 402BB, 400 auto, Extreme Energy 262 Comp Cam (will have shortly), 3:42 gears with a Eaton posi, Thorley headers, and soon a performer manifold. I have a neighbor who has the Avenger and has had real good luck. My interest are low end and mid range torque.
Just my .003 cents worth.
Dewayne 70cst

**70cst** · 03-29-2002, 10:58 AM

Welllll...I made my carb decision today. I went with the Q Jet 1901 vs the Holly Avenger. After listening to the feedback from this board and talking to the guys at Summitt I came to the conclusion that the Q Jet was the better option. Also I want to keep Ksucatz employed! It's good to have boards like this to get info from.
Thanks Guys!!!
Regards,
Dewayne 70cst

03-24-2002, 08:56 PM	#1
mark25 Registered User Join Date: Feb 2000 Location: Vassar,Ks 66543 Posts: 375	CARBURATOR WAR!!!!!!!!!!! my 670 Holley street avenger is about to get the best of me!!! thinking of switching to a 750 Carter AFB manual choke. this is on a healthy 350, 380 horse/385 torque, 10.25 compression, with a Comp Cam 280H (480 lift, 280 duration, 230@.050, 110 lobe seperation). if you run my engine through carb formula (cubic inches x max RPM / 3456) i get 616 cfm needed to run motor plus holley/summitt says add another 20% for performance which brings me to 739 cfm carb. could a 750 live on this motor and not be too much carb. have seen a few guys on this board that said the 750 is a little overkill. what do i do????? HELP!!!!!!!! __________________ '72 C-10 Cheyenne Super, 402/TH400, Bucket Seats, tilt, tach, AM/FM & shoulder harnesses and a ground up restoration

03-24-2002, 09:13 PM	#3
Brad69 Crash Test Dummy Join Date: Feb 2000 Location: Wilton, Ca. USA Posts: 201	Holley's website says to use the 670 for stage 1 engines, and go one size up for stage 2 or 3. They define stage 1 as carb/manifold/headers, stage 2 as adding a cam, stage 3 as ported heads. __________________ The more hair i lose, the more head i get. Build Sheet: 1969 C-10 short fleet Constructed by taking a 3/4 ton rolling frame from one truck, adding a rust free AC Cab from another, then a bed from another, 1/2 ton front suspension & brakes from another,add in one Goodwrench crate 350, painted DuPont Arctic White,and driven daily.

03-24-2002, 09:51 PM	#4
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	hey mark...thats just about the same set ill be running...hows that 280H? do u still have plenty of low end torque? what kind of trans and rear do u have? __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

03-24-2002, 10:48 PM	#5
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	YES THE 750 WILL WORK, I wouldn't go to much more though sam __________________ 72 LWB chevy truck. Pasadena, Texas

03-25-2002, 10:11 PM	#6
704x4 Registered User Join Date: Feb 2002 Location: Greene, Iowa Posts: 150	bigger isn't always better i have a 370horse/355 that i never got to run right with a 750 edelbrock(carter). i had a hell of a hesitation off idle so bad it would die every once in a while i sold the 750 and bought a 600 and i have never had a better running small block the 750 was a waste of time and money, call the edelbrock tech line at 1-800-416-8628 and have all of your engine info ready(be prepared to wait 20 mins) they will tell you exactly what you need. just didnt want you to go through what i did __________________ 70 3/4 ton 4x4 FOR SALE Greene, IA

03-24-2002, 09:10 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Go for the 750. Even a stock one will nomally benifit from a 750 over a 600. Formulas be damned, it always seems to be true. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. Need to pick up the one ton Longhorn with a PONTIAC 350/350soon. Thanks every one! Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

03-25-2002, 10:20 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	If you ain't happy with a 750...I'll trade you for my new Eldebrock 600. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. Need to pick up the one ton Longhorn with a PONTIAC 350/350soon. Thanks every one! Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

03-25-2002, 10:34 PM	#8
raychevy Registered User Join Date: Jul 2000 Location: Evansville, Indiana USA Posts: 485	On my stock 350 it had a 750 edelbrock. Too much fuel if you ask me. If I gave the truck more than 45 percent throttle, nothing but black smoke from the rear. I could accelerate faster at 45 percent than more pedal because it would pour fuel down it. Gas could come out the tailpipe sometimes.

03-27-2002, 12:02 AM	#9
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	ya gotta give the motor what it wants... primary jetting, metering rods etc. all come into play... i had a 1407 edelbrock in my'72 c-20... looked nice, ran straight out of the box... but it didn't run as well as my Quadrajet cause i didn't feel like tuning it... check out: http://www.montecarloss.com/technical.html#Induction __________________ Beat it to fit, Paint it to match...

03-27-2002, 04:53 PM	#10
guypm Registered User Join Date: Feb 2002 Location: orange, tx usa Posts: 167	ive got a 750 holley double-pumper on mine and i absolutely fricken luv it. im running a 280h comp cam,700r4,3:73 rear(open and would rather a posi...need $$$)performer rpm heads, roller rockers,performer rpm intake. try it you'll like it too. Guy __________________ guypm 1971 SWB Fleetside/350 performer rpm heads &intake/ holley 750dp/1.5roller rockers/MSD6a/700r4 1650stall/one piece driveshaft/3.73 open/dynomax ceramic coated headers/3chamber flowmasters/

03-27-2002, 07:06 PM	#11
Stepside Gasser Join Date: May 2000 Location: Thomasville,NC USA Posts: 456	670 is plenty. Lean is horsepower... to a point. Is it misfiring? Does it get hot at idle? If not, you're not too lean. Read the plugs. Here's what I have in my 70: 355 CI, 10.25/1 flat tops 461 Double Hump heads (64 cc). Fully ported (by a NASCAR Modified engine builder) 501/292 Cam 70 Z-28 LT1 Dual Plane intake 650 (4777) Holley (I haven't bought a new one since 1984) You have to study about Holleys. I've had 750's, 780's.,850's, and even a 600 on my truck. The 650, with some tuning, screams. I got all the other carbs running fine... even the 600. Had to put 780 metering blocks on the back side. Great gas milage. But ran hot at idle. I put a 650 base plate on it solved that, with a little idle circuit porting. What I'm saying is, if you want all the power your motor can give, "build" a Holley. If you want a maintenance free carb, "buy" one of the AFB styles. Sorry for rambling ------------------ 70 sstep tubbed, Muncie 68 swb LT-1 __________________ :thud 70 sstep tubbed, Muncie, double hump, snowflake,

03-27-2002, 10:58 PM	#12
704x4 Registered User Join Date: Feb 2002 Location: Greene, Iowa Posts: 150	raychevy thanks for not talking out your a##, and not giving this guy advice that he doesn't need. i hate to say it but it doesn't impress me when someone says that they have a big carb infact if most people understood how a carb works (not saying i'm an expert) they would know that there is such thing as too big of a carb, too much fuel, and running too rich. often the symptoms blammed on lean conditions are the exact opposite! __________________ 70 3/4 ton 4x4 FOR SALE Greene, IA

03-27-2002, 11:05 PM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	'70, you are right, but I have never seen a 350 that has any performance parts on it not react favorably to a 750. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. Need to pick up the one ton Longhorn with a PONTIAC 350/350soon. Thanks every one! Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

03-27-2002, 11:30 PM	#14
704x4 Registered User Join Date: Feb 2002 Location: Greene, Iowa Posts: 150	mail thankyou for the response i was just speaking from experience i have had, and i thought it would help the guy out it was too much for my 355 it ran way to rich i even tried to recalibrate it. then after i talked to edelbrock the told me it was too much performor intake crane roller rockers 1.5:1 sportsmanII 64cc angled plug heads 2.02/1.60 9.5 to 1 compression flat top pistons comp cam 12-231-2 hooker headers i wasn't getting on your case, i just hear the big carb thing too much. sorry __________________ 70 3/4 ton 4x4 FOR SALE Greene, IA

03-27-2002, 11:40 PM	#15
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	I know what your saying man. no harm done. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. Need to pick up the one ton Longhorn with a PONTIAC 350/350soon. Thanks every one! Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio



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03-28-2002, 02:14 AM	#16
aesj2 Registered User Join Date: Feb 2002 Location: Ferndale, Michigan, USA Posts: 94	Just use a BB Q-Jet. It will flow 780 cfm and get better mpg on the highway.

03-28-2002, 09:16 AM	#17
DANTIP Registered User Join Date: Sep 2001 Location: Fort Wayne, Indiana, USA Posts: 1,890	I HAVE HAD EXCELLENT RESULTS FROM A EDELBROCK 600 W/ELECTRIC CHOKE ON MY ZZ3 350 (345 HP). GREAT THROTTLE RESPONSE, EASY STARTING, NO SMOKE, AND GOOD FUEL ECONOMY.

03-28-2002, 03:47 PM	#18
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,374	I'm about to purchase a Holley Avenger 770 for my 70cst. The truck has a 402BB, 400 auto, Extreme Energy 262 Comp Cam (will have shortly), 3:42 gears with a Eaton posi, Thorley headers, and soon a performer manifold. I have a neighbor who has the Avenger and has had real good luck. My interest are low end and mid range torque. Just my .003 cents worth. Dewayne 70cst __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

03-29-2002, 10:58 AM	#19
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,374	Welllll...I made my carb decision today. I went with the Q Jet 1901 vs the Holly Avenger. After listening to the feedback from this board and talking to the guys at Summitt I came to the conclusion that the Q Jet was the better option. Also I want to keep Ksucatz employed! It's good to have boards like this to get info from. Thanks Guys!!! Regards, Dewayne 70cst __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

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