NJey1985

Hi all,

Firstly apologies for asking a rookie question as this is my first carburetter car. 1969 corvette.

If i am cold starting the car, I pump the gas pedal a couple of times with the key in the on position and start the car. Does doing this automatically set fast idle? I know it sets the choke. I can disengage fast idle by blipping the throttle?

If I am warm starting (lets say the car was switched off 2 hrs earlier) the car I wont need to pump the gas pedal to set the choke? I can just start without touching the gas pedal?

If the car is somewhat warm and I set the choke then the choke spring will partially or fully open the choke valve depending on temp? Will the car still fast idle?

Essentially when should you apply choke and does fast idle automatically adjust itself?

Please let me know what the correct procedures should be for warm and cold starts.

Thankyou

Alan 71

Hi NJ,
There are starting procedures in the Owner's Manual.

They are for starting with a COLD engine.
Starting with a WARM engine.
Starting with an EXTREMELY COLD Engine.
Starting a FLOODED engine.

They all presume that the divorced choke is operating properly.

COLD.... Fully depress accelerator, slowly release, crank with foot OFF accelerator.
WARM ... depress accelerator about half-way and hold, while cranking.
EXTREMELY COLD....depress accelerator fully and release 2 or 3 times and then crank with foot off accelerator.
FLOODED engine.... depress and HOLD accelerator to floor while cranking.

Remember choke must be working. Have you been able to check it's operation with the engine both and at operating temperature?
Regards,
Alan

Choke in closed position, engine is COLD.


Choke in open position, engine is WARM.

kanvasman

To add to the correct info that Mr. Alan has given you, make sure that when the choke is closed there is the correct gap between the butterfly and the carb body. I don't know what it is off hand, but when you get that number, find a drill bit that comes closest to that measurement. Place the bit between the two parts to keep the butterfly open that much. And DO NOT drop it into the carb!!! Then adjust your choke accordingly. Having the wrong gap throws everything else off. God luck.

lars

There should be no gap at all when the choke snaps closed when the throttle is depressed. The gap only occurs when the choke pulloff cracks the choke open after the engine has started. This gap, measured between the forward lower edge of the choke plate and the airhorn casting is 1/4". Alan's photos and descriptions are all correct.

Lars

calwldlife

carbs and fuel injection are very different and starting is different.
fi is easy, turn key. fuel is under pressure and squirted
into cylinder.
computer controls everything.

carbs need air drawn thru to suck gas into cylinder.

when an engine is cold it needs more fuel.
that is where the choke blocks air intake and creates a
more fuel mixture to fire engine.

each carb engine reacts a little different to how much
extra fuel mix it needs.
how cold etc.
this will be learned by you as time goes on.

pressing the gas pedal squirts raw gas into the manifold.
this is done by pistons called accelerator squirters.
these allow for gas to be injected for increase in rpm when throttle opened.

this is where the 1 or 2 pumps come in before starting.
too many pumps will flood mixture and cause hard starting.

then you will need to figure out how much gas pedal you need to use,
1/4, 1/8, 1/2 pedal for starting a warm engine.
when fully warm, no pedal at all may work.
again, depends on engine.

so, pressing pedal squirts gas.
opening pedal allows air and fuel to be sucked in.

you will figure it out.

drwet

Corvette poetry

NJey1985

Thanks Alan for the procedure. I really need to get a copy of the owner's manual.

The choke appears to function correctly and had the fast idle set by my mechanic.

On cold start how long does it usually take for fast idle to drop back down to normal idle? I was advised to let the car warm up for 4-5 minutes

lars

Up to 10 minutes.

Lars

drwet

I have a Holley 770 Street Avenger with electric choke. It works well, but the choke comes off too quickly. It starts well and runs well once its warm, but from about the two minute mark to about 7 or 8 minutes when its warm, it wants to stall. Adjusting the choke coil doesn't make a significant difference. Any way I can slow the choke coming off?

corvetero

I'd say the more tension you apply to the butterfly with the coil when fully closed, the longer will take to start opening.

Your coil might be defective though.

lars

The slowest setting you can get on your choke is the setting that just barely brings the choke to the full-open position when it's fully warmed. To do this, apply power to the choke coil for at least 10 minutes (or do this after you've been out for a drive) so the choke is as hot as it will get. While keeping power to the choke (so it doesn't start to cool down during adjustment), loosen the choke housing screws and rotate the housing so that the choke starts to close from the full-open position. Turn it back just a touch to assure that it will go full-open and vertical, with little or no pre-load on the coil spring. This will be the "slowest" position possible with your specific choke coil. If it's still too fast, try a different choke coil - no two act the same.

Lars

drwet

The choke functions exactly as designed. It is an electric choke so there is no relationship between the actual operating temperature of the engine and the rate at which the choke comes off. On a high performance engine where we do not have an EFE valve and/or a heat crossover passage in the intake manifold, the engine warms up much more slowly. I have my choke set so that it is just off when the engine is at operating temperature. Problem is the rate at which it comes off. The choke comes off before the engine is warmed up. Holley should make choke coils that operate at different rates. I wonder if installing a resistor in line with the choke coil would slow down the warming. Anyone know enough about electronics to answer that?