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Gas in #7 and #8 Cylinders
I don't know if any of you have seen this before but after letting my 69 Camaro drag car sit a while, when I went to turn it over, the engine would not crank. Plugs were removed and when the engine was cranked, gas came out of the plug holes in #7 and #8 cylinder. I sure it was gas and not water because it was colored blue like the fuel (VP C12) and it evaporated right away. After rotating the engine and clearing the cylinders, the engine would crank ok with the plugs in. I have not fired it up yet. Often I would activate the fuel pump when it sits for a while to avoid having the gas evaporate out of the carb (Holley 4150). The car is usually kept in a hot garage (85 degrees). Could it be that when the engine was turned off last that the #7 and #8 intakes were in the open position? Maybe the gas did evaporate out of the carb and when I turned on the electric fuel pump initially the floats were stuck and a lot of gas could have poured into #7 and #8?
Any comments? Do you see any issues with firing up the engine? Should I throw some oil in the cylinders first in case the gas "washed" down the cylinders? Any help would be welcome. |
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Gas in #7 and #8 Cylinders
Thanks for your responses and suggestions.........I'll probably try firing it up on Friday.....hope it runs without issues.
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Yes, before you light it up next time a couple shots of light oil like Marvel Mystery Oil is a good idea. Given that cars don't use wobble pumps to prime the engine but the carb has an accelerating pump which will provide the same service of priming the engine; the start up procedure would simply be to turn the fuel pump on to charge the float bowls, pump the accelerator pedal a couple times to prime the engine, start to crank it, then switch the ignition on. This is also a good procedure if you're running a lot of initial spark advance as the engine can gain some RPM on the starter before the ignition is switched on which helps prevent backfires while the starter is engaged. Bogie |
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If you are starting off with dry bowls we do not recommend using the electric pump to refill the bowls as it can damage the floats and/or needle and seats. With an empty bowl same as a new carburetor install our recommendation is to prefill the bowls through the vent tubes.
In regards to the op issue with the fuel prior to restarting the engine is there still fuel in either bowl or does it empty one or both? Does the rear metering block have a power valve or plug in it? |
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I do not see why it would be an issue to fill the bowls w/an electric pump- as long as the pressure is correct. If you had a mechanical pump, fill the carb through the vents to avoid unnecessary cranking. |
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If you read our carburetor install manuals you will see we recommend filling the bowls through the vent on cars with electric pumps. Although it does not do it every time sometimes the fuel is pushed into the empty bowl faster then the air can escape and the result is that with a brass float it can collapse the float and on a nitrophyl float it can bend the float bracket. We have also seen stuck needle and seats from this as well. |
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The only other thread I've responded to that you had also responded to was HERE. You had said: "A 750 Demon will flow a little over 900 cfm." I asked: So the obvious question is: "Why is it rated at 750?" A discussion regarding this ensued. Hardly what I would call "disagree with a lot of what we say". Back to the subject at hand- In my experience I have had no issues filling the float bowls w/an electric pump. BUT- this is w/Holley (as well as Q-Jet, Carter and Carter-type) carbs- I have zero experience w/BG carbs- BG might have problems w/collapsed floats, bent brackets and stuck needle/seat assemblies that do not appear in Holley carbs or the other carbs I have filled using an electric pump. And the OP has a Holley- NOT a BG. Holley doesn't recommend any particular procedure to fill the float bowls on a new carb installation, carb (4777) instructions HERE only say to start the engine. No warnings of impending failures due to the BG-related problems. From a product liability standpoint, I can see a manufacturer giving the warnings that are mentioned. |
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What type of intake do you have, dual plane or open plenum? I would check the rear float level and the float. Might have collapsed or have a pin hole on the seam. I've found the latter before.
Last edited by sqzbox; 09-30-2009 at 05:26 AM. Reason: spelling again |
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Considering our carburetors use some of the same floats as the Holleys the chance is there for this to occur and it is not strictly a Demon problem as you would like to make it out to be. I AM fully aware that the op has a Holley and we were just trying to help and give CORRECT information even though he is not using our product. |
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http://www.jegs.com/InstallationInst...10-O-80586.pdf |
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Gas in #7 and #8 Cylinders
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I have an open plenum intake. After the incident occurred (just once), I have not seen it happen again....both fuel bowls are holding good level and the vents seem to be working ok..this is of course just when the fuel pump is activated...I will know more when I fire it up and run for a while. Before that of course I will pull both bowls and check the condition of the floats etc. Just want to thank all of the responders for the advice and help. |
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