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11-16-2019, 01:33 PM | #1 |
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Float gauge for Holly 1901 carb
Where would I find float gauge for a 2 bb Holly 1901 for my 53 Merc.? It has been running very rich and so I thought I would start with the float settings, and see if the economizer valve need to be replaced.
It has been 10 years since I rebuilt the carburetor. Last edited by Merc Cruzer; 11-16-2019 at 01:49 PM. |
11-16-2019, 03:04 PM | #2 |
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Re: Float gauge for Holly 1901 carb
Considering that the float chamber is virtually identical to the 885 Holley, I suspect they are the same.
The fuel level spec. for the 885 is (1/2" ±1/32") from the top of the chamber. That is when filled with fluid.
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11-16-2019, 03:32 PM | #3 |
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Re: Float gauge for Holly 1901 carb
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11-16-2019, 06:05 PM | #4 |
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Re: Float gauge for Holly 1901 carb
The float level for a 1901 model Holley ('52 and '53 Merc.) is 5/32" measured at the top toe of the float with the float all the way up. 1/2" is what the actual FUEL level is supposed to be with the float set at 5/32". This is all out of my old Holley parts and specs manual.
Sal |
11-16-2019, 06:39 PM | #5 | |
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Re: Float gauge for Holly 1901 carb
Quote:
Last edited by Merc Cruzer; 11-16-2019 at 06:47 PM. |
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11-17-2019, 10:10 AM | #6 | ||
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Re: Float gauge for Holly 1901 carb
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Quote:
Quote:
Sorry for any confusion caused by my use of the word "float" instead of 'fuel'.
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11-17-2019, 01:01 PM | #7 | |
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Re: Float gauge for Holly 1901 carb
Quote:
When I measure the "actual FUEL level is it 1 1/16 ", measured from the bottom of the bowel, not 1/2". (picture #4) Am I measuring from the wrong location? I am using water for the measurements and photos. Last edited by Merc Cruzer; 11-17-2019 at 01:06 PM. |
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11-17-2019, 02:18 PM | #8 |
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Re: Float gauge for Holly 1901 carb
As stated in my post #2 above, 1/2" from top of chamber.
I never did it with water as it is a different density than gasoline and will give false results. The toe end is furthest from the valve arm.
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11-17-2019, 02:47 PM | #9 |
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Re: Float gauge for Holly 1901 carb
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11-17-2019, 08:20 PM | #10 |
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Re: Float gauge for Holly 1901 carb
I guess all of the replies answered your question.
"Yes, indeed correct. Sorry for any confusion caused by my use of the word "float" instead of 'fuel'." 51 MERC-CT, no problem. I just wanted to avoid any confusion for Merc Cruzer. Sal |
11-18-2019, 05:47 PM | #11 |
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Re: Float gauge for Holly 1901 carb
First let me thank all of you for your information and patience.
I took the top off the carb today and found the level way less that 1/2" from the top. I tried resetting the float to correct the level, but it turned out to be the float needle and seat along with the float. The float needle would not seat well enough to stop the flow of additional gas after it had reached the full level. The float had been repaired previously and one of the float bulbs was not the full size. Therefor it would not provide enough pressure to seat the needle correctly. I replaced the needle and seat along with replacing the float with a full size one, in allot better shape. (the float, needle and seat I used, is in the second set of pictures above, in a backup carb) This seems to have corrected the float issue, so now all I need is to take the car out for a 20 mile test run then pull the plugs to see if they are cleaner. Thanks again for your information. Last edited by Merc Cruzer; 11-19-2019 at 11:24 AM. |
11-18-2019, 06:01 PM | #12 |
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Re: Float gauge for Holly 1901 carb
I have been rebuilding this style of carb since around 1967. Both 2 barrel and 4 barrel and have always just set the float level to spec and never worried about the exact fuel level in the bowl. Never had any issues related to fuel level unless the fuel pressure was too low or too high.
Sal |
11-18-2019, 08:14 PM | #13 | |
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Re: Float gauge for Holly 1901 carb
Quote:
Any insights you can provide to this carburetor? Last edited by Merc Cruzer; 11-19-2019 at 10:09 AM. |
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11-19-2019, 12:30 PM | #14 |
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Re: Float gauge for Holly 1901 carb
Merc Cruzer,
Other than a good inspection of everything and all of the passages/channels, just make sure the economizer diaphragm doesn't get pinched when installing. I find it easier to collapse the spring on it and tie it collapsed with some tag wire. This way it's not trying to pull on the diaphragm when installing. Also put some light oil on the screw threads for it, so they don't catch and twist the diaphragm when tightening. Also they are prone to a fuel leak where the large brass screw/plug goes over the float valve. You can also use a large O-ring on the brass plus instead of the round gasket. I would keep the float level at spec or even 1/32" higher to avoid a possible hesitation. If your engine never had a hesitation, then just set the float to spec. (5/32"). Other than that just common sense and patience. Sal |
11-19-2019, 12:50 PM | #15 |
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Re: Float gauge for Holly 1901 carb
Any thoughts on a blocked off heat riser and the car running rich? I block off the heat riser in the summer to reduce the heat on the carb. But now it is Fall/Winter. My search of prior "heat riser" threads, pertains to reducing heat off of the carb, rather than how it effected the function of the carb.
Last edited by Merc Cruzer; 11-19-2019 at 02:11 PM. |
11-19-2019, 05:24 PM | #16 |
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Re: Float gauge for Holly 1901 carb
If the engine is actually running rich (spark plugs getting darker), then some possibilities are fuel level too high, economizer diaphragm pinched or leaking (causing power valve to be opened earlier) or maybe the float starting to sink (kind of rare).
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11-19-2019, 06:02 PM | #17 |
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Re: Float gauge for Holly 1901 carb
I can confirm that the float valve was not closing and the bowl was being overfilled. That has now been corrected.
I would take it that the blocking off of the heat riser would not have caused the carb to run richer. Thank you, |
11-19-2019, 09:12 PM | #18 | |
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Re: Float gauge for Holly 1901 carb
Quote:
Blocking that tube will prevent hot air from reaching the heated element in the automatic choke as it should. This will cause the choke to stay closed longer than it should and thus, run rich.
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11-20-2019, 10:02 AM | #19 | |
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Re: Float gauge for Holly 1901 carb
Quote:
There is a good chance that I have corrected the issue, but thought since I was working on the carb, I would look for any other caused of running rich. I have already reduced the size of the jets due to my altitude 8300 ft. The weather has turned, delaying my initial test run. Maybe later this week. Thank you for the suggestion. Last edited by Merc Cruzer; 11-20-2019 at 11:09 AM. |
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11-20-2019, 12:24 PM | #20 |
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Re: Float gauge for Holly 1901 carb
I didn't realize you were at that high of an altitude. You may have to reduce the main jet as much as about 4 or 5 sizes because of the thin air. A trial an error thing. One advantage of modern EFI systems.
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11-20-2019, 05:50 PM | #21 |
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Re: Float gauge for Holly 1901 carb
I am currently running 54's, as they are supposed to be appropriate for 5,000-10,000 ft. Most of the car shows and cruses are in Denver - 5,280 ft. Coming home from Denver involves a 13 mile section that you climb over 3,000 ft. I have jet sizes down to 49, if I need them.
I am really hoping that correcting the flooding issue, that I have confirmed, will solve the issue. Snow for the next three days. You are right, modern EFI, is a great advantage in our daily cars (Jeep and Mini Cooper). I read other postings about compression after a new build. Altitude makes a big difference. What most would consider a worn out engine, is the compression for a new rebuild at this altitude. Last edited by Merc Cruzer; 11-20-2019 at 05:58 PM. |
11-21-2019, 11:05 AM | #22 | |
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Re: Float gauge for Holly 1901 carb
Quote:
I am assuming that the idle tubes and the well tubes (attached picture top left and right) are one size only for this carburetor, since they are not marked with a size. Should the main jets and the power valve (attached picture - lower) all be the same size? I note that I am currently running 54 main jets yet the power valve is a 52. I note that there were carbs for the Canadian market. The "M" carb I would guess was to show it was for the Mercury in 52'-53'. Last edited by Merc Cruzer; 11-21-2019 at 12:09 PM. |
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11-21-2019, 01:35 PM | #23 |
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Re: Float gauge for Holly 1901 carb
Wouldn't it be nice to adapt an 'aircraft' carburetor just for your situation.
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11-21-2019, 06:14 PM | #24 |
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Re: Float gauge for Holly 1901 carb
"Sal,
I am assuming that the idle tubes and the well tubes (attached picture top left and right) are one size only for this carburetor, since they are not marked with a size. Should the main jets and the power valve (attached picture - lower) all be the same size? I note that I am currently running 54 main jets yet the power valve is a 52. I note that there were carbs for the Canadian market. The "M" carb I would guess was to show it was for the Mercury in 52'-53'." Roy, I'm not sure if the main well tubes or idle jet tubes (with threads on them) are all the same size, but the manual calls for #54 idle tubes. Don't think that means .054". The well tubes are actually air bleeds for the main system. Main jets are not always the same size, but your carb for sea level originally came with #56 main jets, so you may have to go smaller than #54's. The power valve (#52) has two .037" side holes. The "M" at the end of the carb part number isn't for Mercury. It's just the latest alphabetical rotation of revisions for the carb. (Before it, was the "L"). Sal |
11-24-2019, 05:26 PM | #25 |
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Re: Float gauge for Holly 1901 carb
I always try to provide a followup after correcting an issue.
The flooding issued is now resolved, with the correct setting of the floats. I had a chance to take it out this morning for a 20 mile run. It seemed smoother, more powerful and did run a bit cooler. The cooler water temp, might have been simply due to the ambient temperature during the run was 49 degrees. I am now dealing with a new issue: a slight hesitation when accelerating from a stop, but nothing big. I have to give her credit, I had the heater on, but not the fan and it was more than comfortable. Remember mine is a convertible and they leak cold air something terrible. My question now, is, sicne the car has been running rich for a considerable period of time, I would guess the engine is quite carboned up. How long should it take to clean out the carbon? My worst plug has always been # 6. Attached picture is of plugs # 2 (on left) and #6 (on right) Last edited by Merc Cruzer; 11-24-2019 at 07:58 PM. |
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