Topic: hesitation of throttle
in Forum: C3 Engines
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
when i step on the throttle the engine has a large hesitation, like it is choking, then it will kick-in. not very noticeable if the RPMs are kept high, but if there is a large jump in amount of throttle used it will hesitate....
it's a 350sb, bored 0.060, torquerII intake, mech fuel pump, 650 holley dbl-pmp carb, k&n air filter
any suggestions? thanks!!
SPONSOR AD:: (Our Sponsors help support C3VR)
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
How long has this been going on...recent or since the modifications were done on the car?
I would look first at the carburetor...double pumper could be putting too much fuel in the carb bowl on acceleration, it could need adjustment or even re-jetted to match the cam and intake combination. The floats could be out of adjustment as well. I'm not all that familiar with Holleys, but they're known for needing regular adjustments compared to Q-Jets or Edelbrocks.
The Torker intake is a single plane design, that will create some idle and low end acceleration issues compared to a dual-plane intake since it's designed as a high rpm intake, but a properly set up carburetor can less that effect.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
I'd definitely agree with a carb problem. Either the front accelerator pump is waaay too loose(starving for fuel), or it may have "squirters(discharge nozzles) that are too large(flooding).
It could also be a timing problem.
Does it backfire or anything like that, or does it just fall on it's face when ya goose it?
It could also be a timing problem.
Does it backfire or anything like that, or does it just fall on it's face when ya goose it?
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Former Member
Send PM
Oak Creek, WI - USA
Joined: 5/21/2008
Posts: 1965
Vette(s): 1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!
Yup, thats my vote also. Been there, dun that, got the t shirt for cab problems with my 81. The float in the carb was in really bad shape as well as various seals. My 81 hesitated real bad upon quick acceraration. Fell on its face and choked herself out. Much better after carb rebuild.dskopp 2010-01-26 20:38:50
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Do you have a friend with a vac secondary or Edelbrock carb? See a black cloud of smoke when you get on it from a stand still? I had a 69 Malibu with a very similar set up but had highway gears. Switched to a 650 Vac Secondary carb out of the box and cured the problem - I also think for initial acceleration, you're better off with a dual plane if you don't have the gears.
How big is the cam?
LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America
Support Our Troops 
I had an aftermarket air cleaner that interfered with the accelerator pump. Mine had the same hesitation you're describing. It wasn't on a Holley though, it was on my Q-Jet.
A GM aircleaner straightened it out. The clearance on the underside of it did the trick. (Thx. again DaveM!)
Kevin
Former Member
Send PM
Lusby, MD - USA
Joined: 10/18/2003
Posts: 56
Vette(s): 1981 WHITE ALT WITH ALL THE BELLS
Do your air/fuel screws work ok. Have you checked to see if the throttle plates are down on the transfer slots. If you have another carb. look at it and you will see what I'm talking about.
in Forum: C3 Engines
SPONSOR AD: (Our Sponsors help support C3VR)