Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Is the a way to bench test the economizer diaphragm on a Holly Carburetor Model 1901 (teapot)? The carb used on the 52'-53' Mercury's.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

I use a piece of rubber hose and hold it tightly against the low pressure port then draw a vacuum by mouth on the other end of the hose. It shouldn't have a lot of pressure against it. A vacuum pump could be used instead if you have a good one.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

To test it properly need to clean any dirt and make sure it's dry around the center hole for the air cleaner stud. Then seal both sides of the hole with a small piece of masking tape. I say this because the vacuum channel to the diaphragm passes through this area and is sealed by a brass bushing. The bushing sometimes doesn't seal well. This is why it's important to snug down the air cleaner stud to seal it once assembled again.
You can use your mouth to apply vacuum to the hole in the cover, then see if the diaphragm collapses and stays there. If any leaks (besides a bad diaphragm), it's usually because the diaphragm is pinched. Best to install it with the spring partly collapsed, as to keep the diaphragm flat when tightening the screws.


Sal

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Update: I took the top off the carburetor and did the vacuum test. The economizer valve did not move at all. I tried another top (since I have 4 carbs to scrounge parts from) and installed the economizer valve and redid the vacuum test and the valve moved up and down, as it should.

New question: two of the tops I have for this carburetor have bushing and two don't. The two that don't are slightly different design (per the photo). Over all they appear the same and will fit on this carb. Later or earlier models?

Bottom line I believe this has been the issue (running rich) all along. I will know better after a test run. Thank you both.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Just curious if you have tried running it without the air cleaner? I've tested mine with and without the air cleaner and it almost seems to run better, as if it has more power, without the air cleaner.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

RalphG,

Actually a couple of years ago I did a test involving one modified air cleaner, an original air cleaner and without an air cleaner.

The modified air cleaner involves one that I cut the insides out and shortened the top insert and am using a K&N filter in it (picture below).

As it turns out the modified air cleaner with the K&N filter provided the best performance. of all three trials.

This way it still has the original appearance but uses a cartridge filter. Might just have to repeat the test, to see if anything has changed.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

It looks like the carbs have a little bit different venting design. Ford & Holley played with this stuff on more than one occasion. It seems like all the carb models have some evolution in the time frame they were produced.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Thanks for that information. Looks like a very well done conversion. Neither my 52 or 53 air cleaners have the holes in the side though.
Sorry if I am hijacking this thread. I will let you get back to economizer valves.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Mine didn't either, I cut them in, using a plasma torch. I have attached pictures of before and after the opening were cut in.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

I actually meant the holes on the outside of the cleaner body. I have seen that style opening on the 55 and up Ford and Mercs but not on 52-53.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

These are the stock air cleaners for the US. They are fairly easy to find on e-bay if you are looking for one.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

The kits I have bought recently have contained these washers, that I have been using them to seal the top of the carb. The tops without the brass bushings seam to seal better.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

RalphG,

I took mine out today for a trip down to Denver, to get an estimate for a new interior and top. Going down the hill (8300 ft down to 5280 ft.), it loaded up numerous times, (the car was at idle going down the hill) felt like air starvation and the plugs loading up due to too little air and too much fuel. Ran better coming back up the hill, but then it was under load. Checked the plugs after indenturing home ans they were clean, but felt that was due to the car being under load most of the way home. Plan is to run it without the filter on a test run. I will let you know the outcome. Thanks for the suggestion, my last test was years ago and allot has changed since then.

Merc Cruzer

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Possibly carburetor icing if the engine was not working hard enough downhill? I have not driven mine enough in cold weather to know if these had a problem but it can happen on any gas engine given the right conditions.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

RalphG,

I think you have the air cleaners that were used on the 52' Mercs.

Re: Bench testing the economizer diaphragm on a Holley 1901 (teapot) carb
 

Carburetor icing doesn't happen in cars often due to the exhaust warmed manifold but a long decent like that is where it is most common on aircraft and the reason that they have carburetor heat systems. Normally aspirated airplane engines all have to have a carb air temp gauge and a carb heat system just for this very reason.