The holley alcohol tolerant diaphragm is green colored on one side. This green side is "up" so a green edge can be seen under the cover. The holley old type is all black, but they don't last long with todays 10% ethanol gas. If you have a fuel seepage under the front of your carb or brown sticky puddling in the side valleys of the intake next the the carb this is likely the culprit. The gas evaporates quickly leaving a brown sticky substance that looks like oil but isn't. So I have been putting green ones in drivers and black ones in high point cars that may be judged in the future. Does anyone know of an all black diaphragm that is alcohol resistant? Maybe one from a manufacturer the than Holley?
Holley ethanol tolerant accelerator pump diaphragm
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Re: Holley ethanol tolerant accelerator pump diaphragm
No, however I was looking at the same thing last week. I am planning on using some catalyzed black paint to "blackout" the edges the day prior to installation.James A Groome
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Re: Holley ethanol tolerant accelerator pump diaphragm
Ed, The green pumps are available on line from several suppliers. Make sure when you remove the pump cover that you true up the pump housing. They warp . It will have a concave area at the pump lever. Do not replace the pump without surfacing the housing. A common mistake. If you can't locate one, call me at 314 843-7545. Bob K- Top
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Re: Holley ethanol tolerant accelerator pump diaphragm
Yes, I have been thinking about trying that. I have found that the standard black material pump diaphragms will work for a while but will degrade and slowly seep fuel which will stain the intake manifold, seep and make brown puddles in the intake bolt depressions along the sides of the carb. The green ethanol resistant ones will not do this. I do run the green one in my own 66, but I'm not intending to have it judged anytime soon. Some of my customers want their cars to be as close to NCRS JG specs as possible. The 65 JG specifically warns against any colored gaskets. Im currently assembling a high point 65 coupe that will be judged after completion. I have disassembled a "restored" dated Holley 2818-1 to correct several items that would result in point deductions, the fuel pump diaphragm is one of those. If I put in the standard back diaphragm I'm quite sure it will leak some time in the near future. Thus my initial question about alcohol resistant black diaphragms. I guess I'll have to run a few experiments in coloring the green membrane edges black and see if it works.- Top
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