please help with motor and idle - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69ChevySB · 11-09-2003, 12:00 AM

ok i just put the new 350 block and turbo 400 in when i am cruising sometimes and i come to a stop, when i start to accelerate again my truck feels like it wants to die so i have to give it more gas than usual...also what is my truck supposed to idle at on my rpm gauge? someone said my truck is running to rich thats why it feels like it is gonna die when i start going and a couple times it did die. how do i know what to adjust the 2 screws in the front of my edelbrock carb to? help please i want to drive and break my motor in but i dont want it to die like it did earlier. thanks lots.

rickh · 11-09-2003, 12:35 AM

Best way to set the carb is using a vacuum gauge. You do this with the gauge hooked up and the truck running. You adjust the jets for the most vacuum. You should also have the timming set to 8-10 deg BTDC (or up to 12 if you can get good gas) and the idel set around 600-700 for auto (if I remember correctly).
The jets on the carb can be touchy. Does the truck idle good? How does the exhaust smell? Burn your eyes?
Other causes of stumble could be an air leak on the intake or the carb mount, these are easy to find, if it is idling rough, spray some WD40 around the base of the carb or along the intake gasket, if the idle speeds up, you found a leak.
Was the engine you put in a long block? Maybe the rockers are not adjusted correctly, if so, you will never be able to tune that out with out adjusting them.
Rick H...

shuttermutt · 11-09-2003, 12:39 AM

Check for a vacuum leak before you start twiddling with the carb and, like rickh said, make sure you didn't set the valves too tight. Oh, and be sure you're timing is reasonable (I generally start at 8-10 degrees and creep up until I ping or it gets hard to start when hot, but others prefer more scientific methods). In short, there's at least a dozen things to double-check before you start playing with the carb.

shuttermutt · 11-09-2003, 12:42 AM

Geez, almost forgot. I generally like mine to idle at around 800 rpm (no choke and a known good vacuum advance). I like to set automatic tranny vehicles a tiny bit higher than manuals.

bpmcgee · 11-09-2003, 02:55 AM

One thing to remember is that those needles only set IDLE mixture. Once you step on the gas, the accelerator pump kicks and you're off on the main circuit.

The main circuit mixture is controlled entirely by the main jets, that have to swapped out to play with the mixture.

Brian

11-09-2003, 12:00 AM	#1
69ChevySB dropped69 Join Date: Jan 2003 Location: Grand Canyon State Posts: 120	please help with motor and idle ok i just put the new 350 block and turbo 400 in when i am cruising sometimes and i come to a stop, when i start to accelerate again my truck feels like it wants to die so i have to give it more gas than usual...also what is my truck supposed to idle at on my rpm gauge? someone said my truck is running to rich thats why it feels like it is gonna die when i start going and a couple times it did die. how do i know what to adjust the 2 screws in the front of my edelbrock carb to? help please i want to drive and break my motor in but i dont want it to die like it did earlier. thanks lots. __________________ "And yet I find, yet I find...repeating in my head. If I can't be my own, I feel better dead." -Layne Staley (R.I.P)

11-09-2003, 12:35 AM	#2
rickh Registered User Join Date: Nov 2001 Location: Bellevue Nebraska USA Posts: 74	Best way to set the carb is using a vacuum gauge. You do this with the gauge hooked up and the truck running. You adjust the jets for the most vacuum. You should also have the timming set to 8-10 deg BTDC (or up to 12 if you can get good gas) and the idel set around 600-700 for auto (if I remember correctly). The jets on the carb can be touchy. Does the truck idle good? How does the exhaust smell? Burn your eyes? Other causes of stumble could be an air leak on the intake or the carb mount, these are easy to find, if it is idling rough, spray some WD40 around the base of the carb or along the intake gasket, if the idle speeds up, you found a leak. Was the engine you put in a long block? Maybe the rockers are not adjusted correctly, if so, you will never be able to tune that out with out adjusting them. Rick H... __________________ Rick H.... 69 C10-CST Wood bed floor full power 70 SWB 425hp HOTROD! Full power 71 C20 Camper Special 402 full power, factory dual tanks with gauge switch. FOR SALE!

11-09-2003, 12:39 AM	#3
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Check for a vacuum leak before you start twiddling with the carb and, like rickh said, make sure you didn't set the valves too tight. Oh, and be sure you're timing is reasonable (I generally start at 8-10 degrees and creep up until I ping or it gets hard to start when hot, but others prefer more scientific methods). In short, there's at least a dozen things to double-check before you start playing with the carb. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-09-2003, 12:42 AM	#4
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Geez, almost forgot. I generally like mine to idle at around 800 rpm (no choke and a known good vacuum advance). I like to set automatic tranny vehicles a tiny bit higher than manuals. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

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11-09-2003, 02:55 AM	#5
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	One thing to remember is that those needles only set IDLE mixture. Once you step on the gas, the accelerator pump kicks and you're off on the main circuit. The main circuit mixture is controlled entirely by the main jets, that have to swapped out to play with the mixture. Brian



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