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Old 05-06-2009, 09:31 PM
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4 problems one cause???

I have a 73 vette with a 350 sbc that has the edelbrock performer package 650 cfm carb, aluminum heads etc. After I added all these parts i have had the following problems that I hope will point to one cause

1. Engine fires up immediately after it has sat for 24 or more hours but floods easily and is harder to start if it has run within the past 24 hours

2. Diesels after it is turned off

3. Quick on acceleration up to 4000 rpm then it bogs down for a 1 second sputter then back to strong performance

4. inconsistently sputters on very very hard corners. I do not drive it that hard that often but I noticed it sputtered very briefly when i took a corner fast.

Let me know if I did not provide enough engine info. Thanks in advance

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Old 05-06-2009, 10:32 PM
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Could be a few problems, or could be one, but I'll try to identify what I'm thinking and see if it helps.

I'm thinking its a cam timing/spark timing issue. Unless you recurved the distributor for the new cam, it might not be adding advance until 4000+ RPMs. Its probable that you need to get more spark advance earlier, like maybe all in by 3000. How sure are you that you got the cam on the right tooth when it was installed? If its off by a tooth its either very advanced or very retarded. Judging by the symptoms I would guess advanced.

The 24 hour thing puzzles me, but I'll venture a guess that the carb is too rich. Anyone who has owned a carbureted car knows that you pump the pedal once to get it started when its cold. It not only sets the choke, but it squirts some fuel in the intake. They also know that often times if its sits for a few days you have to pump it a few times, not just once. The fact that it starts cold easily, but starts hard if its been recently run suggests that it might be running rich. Without being there to witness the exact starting its hard to tell.

The sputtering in corners could be a carb float level issue. If its too low, hard corners will let the fuel slosh away from the jets and cause a lean condition.
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Old 05-07-2009, 12:30 AM
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Check this!

Edelbrock and Carter AFB's do not like fuel pressure over 5 1/2 psi ,put a fuel pressure regulator on it and set it at 5 psi and you should be OK,I have seen time and again guys say"but it's a stock fuel pump" that means nothing! there are stock pumps that will test out at 8-9 psi.When your car sits overnight pressure in the lines will bleed off and everything seems fine,after you drive it pressure increases and it has the effect of a high float level causing a rich condition and flooding and dieseling from raw fuel being pushed past the needle and seat from excess pressure after the engine is shut off.
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Old 05-07-2009, 01:39 AM
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Quote:
Originally Posted by ffcagle34

1. Engine fires up immediately after it has sat for 24 or more hours but floods easily and is harder to start if it has run within the past 24 hours. Very odd coincidence? Bad Carb?

2. Diesels after it is turned off. Vacuum leak?

3. Quick on acceleration up to 4000 rpm then it bogs down for a 1 second sputter then back to strong performance. Ignition prob. Bad wire or cap? How old is the coil?

4. inconsistently sputters on very very hard corners. I do not drive it that hard that often but I noticed it sputtered very briefly when i took a corner fast. Low float level

Let me know if I did not provide enough engine info. Thanks in advance
See my answers within quote above
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Old 05-07-2009, 09:00 AM
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I'd start by checking the float level- too high can cause most/all of the problems, too.
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Old 05-07-2009, 05:44 PM
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agree...

I read the OP, had an idea, and Jeff said it.
Check fuel pressure.
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Old 05-07-2009, 06:19 PM
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4 problems / one cause

You can double check the electrical but your problem is definitely fuel related. Make sure everything in the carb is set right and then make sure you have at least six PSI of fuel pressure at idle and wide open. The carb is leaking fuel internally and that's why it diesels and won't start until the excess has evaporated away. HEI ignitions hate extra fuel. The plugs are prone to foul out with the extra gas.
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Old 05-07-2009, 06:22 PM
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4 problems

Bolt the stock Rochester back on and see how it runs. I'll bet it's better and then you'll know for sure about the new carb.
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Old 05-07-2009, 08:37 PM
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thank you all so much. I get home from work tomorrow and will try checking the fuel pressure, looking for vaccum leaks and the float level. I am hoping for one culprit that will solve all of the problems since they seem to be fuel related
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Old 05-08-2009, 07:43 AM
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this reads like a float problem, there are TWO adjustments for a float.. The open level and a closed level, I would start there. New carb, it is wise to check this, shipping and handling effect this . "inconsistently sputters on very very hard corners" I'll bet you hard braking and a U turn will act the same way ...

Fuel pressure ? did you change the pump ? I did not read that you did so nix that idea . only work in the area you have been working in .... Diesels ,, idle to high & timing related 10-12 degrees ..

floods ...... comes back to float level or keep you foot out of it, while starting, so many times I see people pumping the gas peddle starting the car. if a daily driver and cold start one stroke of the gas will do it, if hot just fire it up of course I am talking after the float is verified and timing is all good here .



You are just fine tuning after a nice upgrade ..... float check first and then recheck that timing.
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Old 05-08-2009, 09:44 AM
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Something else to mention. On my edey 1405 if I let it sit for a few days it seemed to lose fuel and go practically dry. I have a toggle switch to kill power to my HEI. I would need to leave the switch off, crank over the engine to get the bowls full and then hit the switch and fire the motor. There are two factory press in plugs under the carb, they were leaking causing the problem. I sealed them with epoxy an now its all good. As mentioned the fuel pressure is critical on these carbs. I installed a holley 12-803 reg on my 80 gpm mechanical pump and set it for 5.5, the out of the box pressure of 7.5 was too much for the edey carb.
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