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Old 03-27-2008, 06:40 PM
Swib Swib is offline
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Default cold start v warm start problems.

So I have a few issues, i'm trying to figure out.

I have a 68 Roadrunner clone, with a 400 in it and it starts cold, but not right away, I have to crank it for a bit and pump the pedal. Once it's started it runs very good, but then when i shut it down after running it up to operating temp, it doesn't want to start again. Could it just be the choke? or is there another problem?

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Old 03-27-2008, 07:14 PM
thatwasfunny thatwasfunny is offline
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what kind of carb?
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Old 03-27-2008, 10:30 PM
Swib Swib is offline
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Edelbrock 1407 750 cfm
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Old 03-28-2008, 12:24 AM
valiant64 valiant64 is offline
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Okay, first things first. Electric choke, mechanical (coil type) choke, or no choke? Also how fresh is this engine?
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Old 03-28-2008, 10:08 AM
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MY340 MY340 is offline
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Cold start sounds normal as today's fuel and most carbs mean the fuel evaporates fairly quickly in the bowls hence the need to crank over a few times and pump the accelerator pump to get it to fire.

Hot start issue may be fuel boil over condition. Make sure you are using an insulator gasket or spacer under the carb. With this condition hold pedal to the floor & crank do not pump pedal.
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Old 03-28-2008, 10:25 AM
peg leg peg leg is offline
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Default Fuel pump

Are you running an electric pump? What is your pressure at the carb?
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Old 03-29-2008, 09:10 PM
Swib Swib is offline
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i'm thinking i might need smaller jets, because when its running and i choke it full it continues to run and not bog down, and when it's cold it needs more fuel and then when it's warm it's getting too much fuel. could that be it?

Its a mechanical fuel pump.

the choke is just manual, with the cable.

the motor has just been rebuilt.
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Old 03-30-2008, 12:58 PM
thatwasfunny thatwasfunny is offline
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Cover the top of the carb primary with your hand to choke it if it dies cool,
if not, vacuum leak. And what do your plugs look like?
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Old 03-31-2008, 11:12 AM
63Fury 63Fury is offline
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Quote:
Originally Posted by Swib View Post
i'm thinking i might need smaller jets, because when its running and i choke it full it continues to run and not bog down, and when it's cold it needs more fuel and then when it's warm it's getting too much fuel. could that be it?

Its a mechanical fuel pump.

the choke is just manual, with the cable.

the motor has just been rebuilt.
You can fully choke it and it still runs? Wow I would say check for a vacuum leak for sure. Check for a leak at the carb to intake gasket and intake to heads. Also check to make sure you don't have any open vacuum lines, if you have power brakes make sure you check the line to the booster. If you can totally close the choke and the engine still runs it is getting air from another some place. The choke controls the air in the fuel to air mixture. The jets (and metering rods) control the fuel. When you apply the choke you are making the mixture richer by reducing the air. If your jets were to big (already rich) and you choke it (more rich) it should deffinatly change the engine RPM, at full choke (choke manually closed all the way) it should stall the engine.
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