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Old 07-11-2006, 07:53 PM
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That makes sense on the timing now. Getting that baseline on the fuel pressure will be nice to know.
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Old 07-11-2006, 08:27 PM
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run your timing down

to 25 deg total dont run so high advance setting superchargers likes to be retarded duh@@!!
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Old 07-11-2006, 09:16 PM
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He's not running 25 degrees of timing.
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Old 07-17-2006, 10:49 PM
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okay, here it is... 9 psi of pressure all the way down the track, retarded the timing 1degree after 5 pounds of boost for a total timing of 24, plugs came out white popping 100ft. we went up jet to 96 jets square, 26 degrees of timing at wot white plugs, popping 1000ft. no difference either way.

we thought maybe bad msd, replaced with new 7al2 box, same thing.

We made some calls to a couple of companies and blower shops, we were told it would be better to run a return line off the regulator than to run it off the pump. Any thoughts on this. I was told to go to 100+ jets as well. I thought this is way too much
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Old 07-18-2006, 05:56 AM
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drewbe,

On a drag race only application you shouldn't need a return line from the regulator. Have you flow checked your fuel system to see how much fuel volume its flowing yet? Where these carburetors calibrated to run on a blower? When you've gone up in jetting how did that affect the rest of the run?
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Old 07-18-2006, 08:50 AM
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We have triple checked everything we checked the fuel pump flow, carbs were built for a blower setup. At the line it smoked a little black with the big jets, not much at all. Checked the plugs after the 60 ft and still white.
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Old 07-18-2006, 08:55 AM
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How long did it take to flow a gallon of fuel through your regulator?

Did you 60' times change at all when you've made your jet changes?

How does it pull in first gear before you shift?
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Old 07-18-2006, 10:56 AM
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My 60 second still down, but the track was not good, it did not pull very well out of the hole nor in 2nd gear. I have to do a flow test.
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Old 07-24-2006, 09:25 AM
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Well we changed the entire fuel system and still have a problem. The 60ft are back. Shut the car down at 60ft and check the plugs they look okay, at the 1000 ft they are lean. Went up in jet sizes same issue but real fat at the line.
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Old 07-24-2006, 10:35 AM
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Hey when running a bypass install it as far away from the pump as possible.

I always plumb the fuel to feed the carbs then continue to the bypass valve. That way the carbs get uninterrupted fuel and the bypass is working off of pressure that is not influenced by any plumbing restrictions.

And look at the simple things like fuel tank vented well etc.
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Old 07-24-2006, 10:51 AM
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Quote:
Originally Posted by camaroman7d
The guys are telling you correctly. Your carbs can't take 19psi of fuel pressure, that's why you were getting the black smoke and poor running engine. You may want to set your fuel pressure a little higher than 6.5 psi, do a little experimenting and see what works best. No boost reference needed.
What kind of carbs? Carters and Edelbrocks will flood at pressures of 6.5 psi or greater. For these carbs, regulate to no more than 5.5 or 6.0 psi.

George
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Old 07-24-2006, 10:51 AM
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Quote:
Originally Posted by drewbe
Well we changed the entire fuel system and still have a problem. The 60ft are back. Shut the car down at 60ft and check the plugs they look okay, at the 1000 ft they are lean. Went up in jet sizes same issue but real fat at the line.

Did jetting up help the way the plugs looked, or the way the car ran up top at all?

Usually if you have to jet up to the point it hurts your 60' time your fuel delivery is not keeping up.
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Old 07-24-2006, 10:56 AM
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drewbe,

Have you actually flow tested the system yet to see how long it is taking to flow a gallon of fuel?
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Old 07-24-2006, 01:26 PM
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We are using Holley 1050 carbs built by Chuck N.

As for the jetting up, the car was real fat off the line once we hit the 1000ft mark it started to pop, we shut it down and looked at the plugs. They looked like they just came out of the box. They are white with orange around the ceramic.

We have power valves in the primary, 6.5 and tried to square off the jets as well as use a 6 spread. No matter what we try we have the same issue. The motor goes lean around the 1000ft and starts to pop.

We did not flow test the fuel system yet, we are going to do this tonight. We just installed a new pump/filter and have the same results. We are thinking the carbs might have to rechecked.
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  #30 (permalink)  
Old 07-25-2006, 11:12 PM
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George, I have run Holley carbs for years. They will take more pressure than many think. I have run as high as 10-12psi, if you have healthy floats and needle/seat assembly, they will hold more than 6 psi.. 7- 7.5psi has been the "rule of thumb" for years. You may be right on with the fuel pressures for Edelbrocks and Carters (same carb) but, I have only used those for street rod/very mild applications. In many of those cases there is no fuel regulator or pressure gauge.

Pressure is only part of the fuel system, flow is just as important if not more important. You don't need to set the pressure all that high.
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