Dan,

I guess we are on our own then.........

I will be coming up with some test results in the next few days and weeks that I could share. I am recording each step and documenting results in 260 mile increments traveling the same route each time for consistency making only one change at a time.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

One thing I've noticed so far is my engine has low vacuum and its running really rich if I turn the screw out (it dosn't take much) and I adjust the idle mixture screw to get best vacuum (16"). I'm thinking about putting my old carb with the pluged hole back on.

Eric,

I wanted to get a little more facts documented before I post but here is a heads up. Don't take it off yet.

I am getting 16" in gear 18" out of gear with the .035/#65 drill hole and a #60 jet. The mileage has gotten better and the power is really, really nice.
I need one more day of driving to document mileage.

If you can simulate that small of a hole on the adjustment, maybe a half turn out stop there and jet up. When you unscrew the brass screw you are allowing more air to pull more fuel through the transfer slot and idle mixture holes for better emulsion blending which gives you allot more power. Feels like a Super Six two barrel now. So you have to add more fuel to balance it out, (bigger main jet). Sounds odd, but I have never felt any 1920 have this much power. All I know is that by doing this mod, there is allot more bottom end power and efficiency and I am cruising at higher vacuum readings and staying away from the power valve.

By having tons more light throttle power I don't need to keep my foot in it as much. It looks like I may hit 25 mpg. I will let you know in a few days.

It should work well on your heavy car or on a truck.

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I just got back from swapping my carb. at my folks house (took day off today...wife's Dr. appointments). I was wondering if that screw made the carb run richer. Guess it does. I thought about running a #55 jet in, but you say to run richer? I haven't drilled any holes in the emulsion hole, just stock size. One other thing I was wondering about. I have several different metering blocks....some with only two balls for the enrichment system, some with what looks like 3 (two one the driver side of metering block, one toward the top). Some also look different in the back as far as some of the holes are missing, some are blocked off. How much of an effect will swapping blocks have? The two carbs I've been playing with are rebuilt ones, and you know they don't have the blocks they came with. Just something else to maybe think about. I'll try a bigger jet this weekend. How does timing play into this?

Eric,

Yes, it makes it run richer at the low end. You know how more overlap on the cam kills the bottom end and lets the engine rev higher? Where as less overlap makes for more torque on the bottom? Well that analogy is kind of like opening up the idle air bleed. The lower midrange on these 1920's are pretty non responsive and flat because the idle air bleed is either plugged or nearly plugged. By opening up the idle air bleed it activates the emulsion circuit and you just wake up the bottom end, which helps to broaden the power band and keep you out of the power valve, resulting in better mileage.
With the air cleaner lid off I can here the difference as I adjust the idle mixture screw where as before I couldn't hear the emulsion circuit working. Sounds like Niagra Falls in there

Goal:
If I can tune this one barrel like a two or four barrel Barry Grant or an upgrade Holley, why not I think the engineers left some room on the table.

I haven't touched the timing at all. It is still at 16 degrees initial. I have run that all last year through the winter and now. That much timing will give you a lean bog if you are easy on the throttle. Stab it or aggressively press down and you will never feel the bog. I am hoping that these mods will eliminate the bog all together. This change has helped to do just that.

Check the carb you just put on, I bet the idle air bleed is blocked off and you won't be able to poke anything through. I have looked at all of mine and they show a hole on the top but you can't get anything poked through. I am guessing they all might be plugged.

My Economaster has the three ball metering block you described and I have two carbs with the two ball metering block and one with the one ball metering block. I like the three ball system because I can pass every car and truck going up I-90 from 405 like a scared jack rabbit. It feels like a two barrel.

Observations:
The last two days after drilling the .035 hole and jetting up to a #60 from a #58 the engine has nice crackle to the exhaust note when it comes on point between 12" and 15". It never sounded like that before, and in that range it has more power and is not as flat feeling as before. Like I said earlier, I am making one change at a time for every 260 miles and logging it. The results are not as fast as a flow bench or a Sun distributor machine, but hang with me I will track them traveling the same route and using the same grade and brand of gas.

Next steps:
Next change will be to try a 612 jet, then a 62 on up to a 64 and log the
changes in mileage and power band width.

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Cool, keep me posted. I don't want to give up on this carb. To be honest, I've never really futzed around this in-depth with a one barrel carb before!

Eric,

Ok, checked mileage and hit 23 mpg with the bigger #60 jet and .035 hole for the idle air bleed. So I am pretty happy with the performance increase and the good mileage. That is a win, win

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

happy to see how far we've come with a little drill. It sounds that if you compile our last week of mailing and add a little of what's been told in this post and you've got yourself a tech note for the site. I'm here for backup (well, I'm thre, at my e-mail) if needed

hi to everyone! I miss you guys! I haven't been logging up and such but I do reminisce about /6.org almost everyday when I have a little time with self.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Eric,

The 61-2 jet provides better mileage yet. I am getting 23.5 mpg. I bought some #62's to try which seem to net the same mileage, but decided to take a big leap and jump to a #64 to see what it would do. I will track mileage for a couple of tanks and let you know.

The added emulsion from drilling the idle air bleed hole seems to really help with power and with mileage. I am trying to narrow down the balance between air and gas.

No bog or hiccup on gentle take offs. It seems to be nice and strong now.

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Now I'm curious......

If the added emulsion helps with mileage and power, why didn't it come that way?

Or did it come that way, and the carb was replaced with a 'rebuild' sometime in the life of the car............

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Now that is a question I have been asking everybody including several carb shops. This is a new OEM 1920 Holley Economaster 12R-7610 (1968-72) and the idle air bleed was covered with lead.



To top that, I checked 3 more carbs that I have and they are all closed tight as well. The brass pin is shoved in all the way so it totally blocks the hole. The dimple in the top looks like a nice hole but is totally blocked. I have tried poking a very fine monel fishing leader through to no avail.



Most folks say heck it's a one barrel who cares.......put on a Super Six or a four barrel and go away....

Since Eric asked about the adjustable air bleed on his, it got me to thinking.

Well, I can say this little mod makes my Dart scoot! It feels like a mild 318 under the hood not a SL6.
Here is a picture of the .035 #65 drilled idle air bleed.





I love to drive the Dart because it is so responsive and punchy! It is allot of fun and I still get good mileage.

My son and I just took it out for a spin. With a full tank of 87 octane and both of us we weighed in at 3660 pounds. It will still break loose on dry pavement. I am sure if I gave this engine so more carb it would really respond!

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

How are BBS's........

Are they more like the modified 1920 "good" or plugged 1920 "bad" ?

And if "bad", is the same modification possible?


(yep, I've got a BBS, but no 1920 to compare to)

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Ed,

I haven't found a BBS yet to look at. Maybe DI or SL6 Dan can comment on the BBS idle air bleed hole size and emulsion circuit. Maybe Dan could post the BBS guide.

Dan posted the 1920 Holley rebuild guide pdf and you can easily follow the diagrams and how the idle air bleed circuit works. That is another thing that got me to thinking along with Eric's questions on tuning the bleed. When I sent the photo of my plugged idle air bleed to Juan, it all became very clear that all my 1920's were not tuned correctly.

So, Juan is coaching me on fine tuning the 1920. I had a lean stumble/hiccup when gently accelerating. If I mashed the throttle it was not noticable, however, my rear end would break loose. So the pump shot was covering up the bog.

Today, I can gently accelerate with no bog! Yes, it will still go sideways If I mash the throttle.

I also sent Dan the pics.

_________________
Aggressive Ted



http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger





74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Stepping on and go sideways. My caravan 2.2L carb isn't doing it yet. Stilll tuning. Mine goes like this step on gas hard, engine go limp and would go even SLOWER in many cases.

Will ever we see the pictures here of modified 1920 stuff?

Cheers, Wizard

That's what the pump shot is supposed to do... cover the leanout when vaccuum is low (lower airflow in the plenum) and gas is no longer properly atomized... where it has to be 'tuned' is making sure you get enough pump shot to cover the bog without 'over doing it' (where it will go from lean/normal to 'drown'/puff of black smoke out the tailpipe, and making sure that when the power valve/economizer valve opens as the mains catch up to vacc. signal it doesn't contribute to 'drowning' your engine).


-D.Idiot