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Thread: Hesitation off idle with new carb.

  1. #1
    Join Date
    Sep 2016
    Location
    Texas
    Posts
    3

    Default Hesitation off idle with new carb.

    Hi. I have a 1982 Chevy C-10 short wide. I let it sit for 3 years and wanted to get it back on the road so I got a new Holley double pumper manual secondary carb model# 4777-7 after installing it, it seemed to run good I reset the timing and went for a drive only to have an issue. At idle, it idles fine but as soon as I give it any gas it falls on it's face and stalls to about 2,000 RPM then burns tires and takes off like a bat out of hell. Down the highway I can fill a small cut out when I give it gas to speed up, but after 1 second it runs fine. Let me say that I don't think my Distributor Vacuum Advance is working, and I didn't have this issue when I parked it. The engine is new has only 3,000 miles on it, and it's a Vortec 350 4-bolt main that started with 350 HP. I put a PERFORMER AIR-GAP (IDLE - 5500 RPM) a carb spacer plate and a Comp Cam part #12-246-3 cam with .490" lift and 230°-236° duration, and the required valve springs 981-16. Only issue is the off idle hesitation it will die & backfire if you hit it from a stop, but if you pump the gas to get it going it will then run. This didn't happen before I parked it, so I don't know if something went bad while sitting, but the carb was just put on it and I drained the gas tank even though it started with the old gas and old carb. Any help is greatly appreciated as no one with in 100 miles knows how to work on cars without computers. I've looked.

  2. #2

    Default

    Brian, look at the stickies in the carb forum your hesitation problem is there. You're having problems with accelerator pump linkage having slack or accelerator pump cams needing to be changed. You're not getting enough gas to cover the transition, period. Also, make sure you look at the idle mixture adjustment procedure, and make sure that's right. Thanks, Sean

  3. #3
    Join Date
    Sep 2016
    Location
    Texas
    Posts
    3

    Default

    69cam, I can't find the right sticky in the carb forum, maybe I need glasses. I did find that I had no timing advance as the vacuum timing on the distributor was bad, so I put a new one and the truck ran great for one day. No backfire, no hesitation timing at warm at idle stays at 15° advanced and don't seem to change much, I would think it would. The next day it ran great, then started to die at idle in gear. After restart and one pump of the gas, it sits at 1500 RPM. I set the adjustment screws as the video shows, but it still don't want to idle anymore. I was thinking maybe when I got gas some trash somehow got into the carb, what do you think about that? It has a filter for the gas right after the fuel pump. It didn't start having the idle issue until I got gas. I always use premium gas. The floats are still set good too. Thank you for your reply.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,966

    Default

    Quote Originally Posted by Brian1982 View Post
    69cam, I can't find the right sticky in the carb forum, maybe I need glasses.
    http://forums.holley.com/forumdispla...-Fuel-Pump-FAQ (Carburetor & Fuel Pump FAQ)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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