chevy 250 with poor cold performance - The 1947 - Present Chevrolet & GMC Truck Message Board Network

big10ratrod77 · 05-25-2011, 07:29 AM

hey guys ill be putting tags on my 79 this week and it still dosent run perfect. the truck has a 250 with pair smog injection, 3 on the tree, and 3.08's. the truck cranks up perfect every time but if it has been ideling for 3-5 mins the truck will not take off to save your life it will just choke off, but when it has been running for 15-20 mins it will take off reasonably good. ive tryed a bunch of stuff to get it fixed, ive replaced the weights and springs in the distributor, new cap and rotor, rebuilt the carb(rochchester verijet), installed a new heat riser, set the timming, bypassed all vaccume controled emissions devices, and attempted to adjust the carb. have eny of yall had this same problem?

**old Rusty C10** · 05-25-2011, 07:55 AM

sounds like the electric choke may be bad or need adjustment

1LowToy · 05-25-2011, 08:41 AM

Try adjusting the choke pull off linkage, to make it pull off less. If it's like mine it runs very lean. My next step is to drill out ever so slightly the idle jet port, when I find another unmolested carburator to experiment with. Plugging off the emissions equipment will only cause you more headaches. There is a vacuum hose leading from the carb the driver's side of the valve cover right above the exhaust that can get burnt through. Big lean spot potential.

dswancutt · 05-25-2011, 02:51 PM

I may be wrong, but I think GM chose to run the choke off the oil pressure switch for that year. Something to think about.
My 76 with the non intergral head is a cold blooded beast and I can remember how my or my uncles 79's ran when cold.

05-25-2011, 07:29 AM	#1
big10ratrod77 Registered User Join Date: Aug 2009 Location: hillborough nc Posts: 410	chevy 250 with poor cold performance hey guys ill be putting tags on my 79 this week and it still dosent run perfect. the truck has a 250 with pair smog injection, 3 on the tree, and 3.08's. the truck cranks up perfect every time but if it has been ideling for 3-5 mins the truck will not take off to save your life it will just choke off, but when it has been running for 15-20 mins it will take off reasonably good. ive tryed a bunch of stuff to get it fixed, ive replaced the weights and springs in the distributor, new cap and rotor, rebuilt the carb(rochchester verijet), installed a new heat riser, set the timming, bypassed all vaccume controled emissions devices, and attempted to adjust the carb. have eny of yall had this same problem? __________________ 77 chevy BIG 10 350/sm465/12bolt w 3.73 bout 240 horse power NO power steerin 79 chevy 1/2 ton 250/three on the tree/3.08s soon to get built 250/floor shift conversion/3.08s 81 mercedes 300d 25 MPG 77 chevy BIG DOOLEY 454/sm-465/14 bolt 4.10s "fully loaded" 73 plymouth duster 225 slant six/230 3 speed/8 1/4 trying to acheve 300 horse six http://www.cardomain.com/ride/3135091 '77 chevy trucks. built to stay tough. life is short build a hot rod

05-25-2011, 07:55 AM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,307	Re: chevy 250 with poor cold performance sounds like the electric choke may be bad or need adjustment __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

05-25-2011, 08:41 AM	#3
1LowToy Registered User Join Date: Nov 2009 Location: Sonora California Posts: 860	Re: chevy 250 with poor cold performance Try adjusting the choke pull off linkage, to make it pull off less. If it's like mine it runs very lean. My next step is to drill out ever so slightly the idle jet port, when I find another unmolested carburator to experiment with. Plugging off the emissions equipment will only cause you more headaches. There is a vacuum hose leading from the carb the driver's side of the valve cover right above the exhaust that can get burnt through. Big lean spot potential.

05-25-2011, 02:51 PM	#4
dswancutt Registered User Join Date: Jul 2003 Location: Franklin, NE Posts: 387	Re: chevy 250 with poor cold performance I may be wrong, but I think GM chose to run the choke off the oil pressure switch for that year. Something to think about. My 76 with the non intergral head is a cold blooded beast and I can remember how my or my uncles 79's ran when cold.

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