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1920 Economaster power valve
https://www.slantsix.org/forum/viewtopic.php?t=19422		 Page 1 of 2
Author:  Marc [ Wed Aug 30, 2006 8:07 am ]
Post subject:  1920 Economaster power valve
I bought one of Dan's NOS Holley 1920 Economasters. It idles beautifully at about 19" Hg. Cruise is good. It pulls 15" to 18" Hg at cruise.

The problem is getting to cruise or trying to accelerate to pass. It just does not accelerate well at higher speeds. Feels like it is way lean. Since cruise is fine I suspect the power valve. The Economaster apparently has a two stage power valve which may complicate things.

The only thing I have done so far is to make sure the vacuum port for the power valve is open to the manifold and it is. Is there an easy test for power valve function? Any ideas on what to check? The 1920 is new to me. I had a BBS before which had good upper end power.
Author:  Eric W [ Wed Aug 30, 2006 10:01 am ]
Post subject: 
Check your jet size. It probably came with a small one, like a #53 or so. Going to a larger size will give you a bigger pump shot, eleminating the hesitation. A #58 should be enough...at least it is for me.
Author:  SlantSixDan [ Wed Aug 30, 2006 1:54 pm ]
Post subject: 
I've got one of the Economasters like I sold you, on my car, and have no sag/hesitation/etc. The difference is almost certainly the fuel! California gasoline is "reformulated", i.e., oxygenated, which means any given amount of it gives a leaner mixture than the same amount of non-"reformulated" gasoline. Eric is correct -- the first thing to try is to go up a few jet sizes. Don't overdo it or you'll spoil your gas mileage. It's easy to pull the main jet on a 1920, just remove the float bowl and then you can unscrew the jet and see what size it is. Don't forget to use a new bowl gasket each and every time you remove the bowl!

Also put in a set of NGK ZFR5N spark plugs, without the metal ring washers.
Author:  Marc [ Wed Aug 30, 2006 4:11 pm ]
Post subject: 
I emailed Holley and they said the stock jet is #552. Do these carbs use the same jets as the 2300, 4150 and 4160 series? I have some of those floating around here.

Can't use that plug-got the taper seat heads.
Author:  SlantSixDan [ Wed Aug 30, 2006 4:56 pm ]
Post subject: 
552 is a #55 jet ..."high precision" series, where the first two digits are the jet number, and the last digit is a 1, 2, or 3 indicating whether that particular jet is on the small (1), medium (2) or large (3) end of the size for the indicated jet side.

On California's oxygenated gasoline, 55 is on the small side. Try a 60.
Author:  DusterIdiot [ Wed Aug 30, 2006 8:04 pm ]
Post subject:  yipes!
Quote:
On California's oxygenated gasoline, 55 is on the small side. Try a 60

I have an old economaster holley I had just rebuilt for my '67, the oem jet size in it was a #56...I would err. on the leaner side to keep the mileage I would suggest trying a #58 if it goes away it's all good, if not going up to a #60 would be next...I had the same problem with mine, I went straight to a #612 like the Holley 1945's...I get great power but lost about 4mpg highway...a number 58 or 59 is goin' back in there soon...


Jet's are fairly cheap, so I would buy one of each for tuning purposes (I may have those sizes in my holley 'box', give me a PM if interested and can't get them from your local shop, or don't want to pay the summit shipping prices.

-D.Idiot
Author:  emsvitil [ Wed Aug 30, 2006 9:10 pm ]
Post subject:  For the Mathematically inclined..........
At most, the reformulated gasoline will require 1 jet size richer:


The reformulated gasoline is either 2.0% O2 or 3.55 O2
which corresponds to an ethanol content of 5.7% and 10.0%
(E5.7 and E10)

Ideal mixture of gasoline is 14.7:1 and Ethanol is 9:1

When you mix them you can figure out the ideal mix as follows:


New mixture = ((percentage ethanol * 9) + (percentage gasoline * 14.7))

or for the above cases

E5.7: 14.3751 = (.057 * 9) + (.943 * 14.7)
E10: 14.13 = (.1 * 9) + (.9 * 14.7)

So if you were jetted correctly for gasoline (14.7) you'd only have the following percentage of fuel you should have:

E5.7 14.3751/14.7 = 97.8%
E10 14.13/14.7 = 96.1%

Since Holley jets fuel flow increases/decrease 4.5% between a jet size, you only need to enlarge the jet by at most one size...

i.e. a 55 would goto a 56


BTW, I'm assuming that the jet in there would be correct for straight gasoline............
Author:  DusterIdiot [ Thu Aug 31, 2006 6:00 am ]
Post subject:  Actually they are jetted lean...
Quote:
BTW, I'm assuming that the jet in there would be correct for straight gasoline............

The stock jets on the 1920's are fairly lean (and the 1974 Holley 1945), that's why the first thing most people advise is stepping up anyway a #57/58 would be good for straight gas under normal conditions for the 1920...and a #60-61 for the 1945 (stock jetting in 1974 was 58, went to 61 in 1975/76)...

Like everybody with a holley you just have to play with the settings and check you plug color... :wink:


-D.Idiot
Author:  Marc [ Thu Aug 31, 2006 6:02 am ]
Post subject: 
OK, bigger jets it is! I keep telling people gasoline ain't what it used to be but they don't believe me. If they worked with these old cars they might start to believe it. I have had this car for 20 years and I do not get as good mileage as I used to. I suspect it is at least partly the lower energy content of the gasoline.

Do these carbs use the same jets as the 2300, 4150 and 4160 series? I have some of those floating around here. I don't know what sizes I have until I dig them out.

Where do you get bowl gaskets without buying a kit?
Author:  DusterIdiot [ Fri Sep 01, 2006 6:14 am ]
Post subject:  Yep...
Do these carbs use the same jets as the 2300, 4150 and 4160 series?


Yes, just use a big screwdriver like those above carbs and switch 'em...


-D.Idiot
Author:  MitchB [ Fri Sep 01, 2006 7:31 am ]
Post subject: 
I am using a 1945 on my 1980 Aspen. From the factory, the carb was setup very lean. I found that when I jetted the carb for correct cruise A/F, it was still lean under power. I had to enlarge the power valve channel restriction and this fixed the problem. So yes, you may have to jet up for a variety of reasons, but depending on how the carb is calibrated, this might not be enough.

Years ago, I built a Ford 2150 carb using a two stage power valve for one of my other cars. I rigged up a tool that allowed me to verify the set points of the first and second stages. I set the first stage to open at a relatively high 11.5 manifold vacuum. This allowed me to gradually ramp the A/F richer from a relatively lean cruise A/F. This carb worked great, giving very good pedal feel and good mpg.

Mitch
Author:  Marc [ Fri Sep 01, 2006 9:32 am ]
Post subject: 
I scrounged around in my junk collection and found a 60 jet. I pulled the float bowl and there was a strange looking spring jammed down in the corner under the power valve levers. I got the book out and it turned out to be the float bumper spring. So I put the spring back where it belongs and left the original jet. It still might be lean but I am going to try it again in stock form before I change jets.

The original jet is a 554.
Author:  SlantSixDan [ Fri Sep 01, 2006 10:35 am ]
Post subject: 
YOIKS! Yeah, that'll cause problems, if the float spring got dislodged and wedged under the power valve actuator. You're doing the right thing to try it out again now you've put the spring back, before changing the jet.
Author:  Marc [ Wed Sep 06, 2006 4:58 pm ]
Post subject: 
I finally gave the car a test drive with the hopefully functional power valve. It is still lean. Definitely need to fatten her up. These are supposedly a two stage power valve. You still can't really feel the first stage. It is still way lean in that area. Apparently the second stage kicks in when you go to WOT as I can feel the difference there.

I emailed Holley and asked where the power valve should open. No response. I guess they don't know. Any one have any idea at what vacuum the two stages should open?

I am going to try the 60 jet since I have it but I am going to try to find a 58 to try to.
Author:  emsvitil [ Wed Sep 06, 2006 5:10 pm ]
Post subject: 
What's the part number on the power valve? (125-xxx)

Bet you can look up that part number and find the specs (probably summit)
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