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Discussion Starter #1
Good morning every one, First I would like to thank all thoues who have anwsered my previous questions so far.

Todays questions are as followes: What is the idle fuel pressure at the carb? I just installed a in-line qauge and am seeing 5 psi.

Also what is vacume at idle, I have 15 inches but from what I was told the cam could be the reason for this I thought 20 or so inches would be correct for a stock cam.

The final question where should I look to find a modle number on a holly carb. I have an aftermarket carb and was told its a 750 cfmdouble pumper, from what I can see its definatly a double pumper but Im not sure what model.

Thanks for any help you can offer.
 

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For Holley model number, look on the front of the choke air horn (front of the primary side up by choke butterfly). You'll see a number like LIST 4776 then a small number (date code) below that.
 

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According to the 1967 Cougar shop manual the idle vacuum reading on a 1967 GT390 should be about 17 inches. This can be found in the table at the bottom of page 8-132.

The original carburetor for your car is a 600 CFM Holley. It is a large carburetor and many people have mistakenly assumed that since it has two fuel inlets that it is a double pumper of some sort. The term "Double Pumper" refers to the number of accelerator pumps on the carburetor. Look down the carb with the air cleaner removed and work the throttle linkage. Does gas shoot down all four barrels from two different shooters?

Like the post above said, get the List number off the air horn. Then go to Holley's website and it will tell you what CFM and type the carb really is.
 

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Fuel Pressure, Carb

According to the 1967 Cougar shop manual, fuel pressure at idle should be 4 - 6 PSI at 500 engine RPM. This information is from the table on page 10-106.

Here's a picture of the correct carb for your car from page 10-84 in the same book:
 

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Discussion Starter #6
WOW thanks for all the quick responses,

I know the carb is a double pumper because of fuel comeing from all four jets so thanks for the comfermation. Ill check for the number and go to Hollys site for further info.

Looks like the vule and vacume are correct, by the way my shop manual is on the way so for the more basic questions Ill be able to consult that.
 
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