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.

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.

Re: Float gauge for Holly 1901 carb
 

Thank you.

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

Re: Float gauge for Holly 1901 carb
 

Thank you for the update and clarification. I will be on the look out for the old Holley manuals at future swap meets, to add to my collection, good source of info for the car and carb. The service manual shows a fuel level gauge, but no luck finding one.

Re: Float gauge for Holly 1901 carb
 

Yes, indeed correct.
Sorry for any confusion caused by my use of the word "float" instead of
'fuel'.

Re: Float gauge for Holly 1901 carb
 

Ok, so I am taking a few measurements. (I have a few of these for back-up, and I though I would get the gauge set first. When you say "5/32 measured from the top toe of the float with the float all the way up", that would be picture #1 below.

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.

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.

Re: Float gauge for Holly 1901 carb
 

Thank you. Remeasured and it is 1/2" from the top.

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

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.

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

Re: Float gauge for Holly 1901 carb
 

Sal,

Any insights you can provide to this carburetor?

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

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.

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).

Sal

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,

Re: Float gauge for Holly 1901 carb
 

If by "heat riser" you mean the tube that is located on the lower part of the intake.
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.

Re: Float gauge for Holly 1901 carb
 

Yes, that is the tube that has been blocked off. I agree, and I thought of that when I initially blocked off the heat riser. I decided to turn the choke to totally lean, thereby neutralizing the by-metal strip and in essence turning it off. It doesn't affect the starting since the garage never drop below 55 degrees.

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.

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.


Sal