I have been through this and through this and I can't find the problem.

Heres the deal-
When the car sits fuel drips from the discharge and soaks the throttle blade and intake floor, so that when I start the car its way rich and sputters hard enough to shake the entire car, then dies. Driving with both feet and smelling harsh gas fumes is no fun

So I clean and rebuild the carb, and it still does it. I found the economizer plate was warped, so I flatten it with 320 grit and reassembled it, but nothing changed

I installed a new float, and reset the level to 3/16s and try again, and still no idle and the fuel drip, so I lower the float to 1/8" (obviously too low, but I am desperate) and no improvement. However as I reassemble everything I realize the idle problem only happens with the aircleaner on, so I mess with that and find the element so plugged it kills the engine! Never saw that before. A new filter and now the car idles, but still loads up after sitting.

Apparently the float wasn't causing any probs, but wheres the problem?

Heres another thing- before I swapped floats, it would idle better if I pulled the small vacuum line that works the pulloff. I fiddled with the mixture screw for best idle, now it sputters with the open line and thats good

But

The mixture screw has no effect until the final 1/4 turn before bottoming out. Obviously that drip is messing up the ratio still.

After all is said and done the only new part thats fixed anything is the filter! And this is getting really old.

I did notice one thing- When the fuel bowl is full, if I tilt the carb the least little bit from level (the flexible fuel line is awesome for this) fuel runs out the discharge

So is there a crack somewhere? or what is going on???


Any help is appreciated

Here is some generic stuff to check in about:

1. How is your PCV valve?(if it's working, it will rattle while running and you can feel it with your hand)
2. Does the PCV port on the carb suck vacuum good and hard? The engine should stall if you pull the PCV hose off. If not, you've used the wrong carb mounting gasket.

If you find that you need to fix 1 or 2, you may be in for a treat, because adjusting the idle mixture screw and idle speed will yield much better results.

The dripping is a bad sign, but I don't really have a full understanding of the internal workings of the 1920. There is a small valve body inside which mystifies me in it's purpose.(other than being part of the accelerator pump) I have always believed it has something to do with idle and the type of problems you are having.

Now that i've moved to the super six, I could drill out the end caps on the tiny valve body and see what makes the whole thing tick, but I'm just too busy to care any more.

13 mpg on a highway trip was just not acceptable

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1980 Aspen 225 super six

True. Your first step, if you have not yet done it:

Remove the metal line that runs from the fuel pump to the carburetor and throw it away. Install a 5/16" IV-flare-to-5/16"-hose-barb brass
fitting in the fuel pump outlet and another in the carb inlet. These
fittings can be had from any well-stocked hardware store that carries the
Dorman "orange drawers" line of springs, fittings, etc. The Dorman part number is 492-024; Everbrass number is 1791.

Between these fittings I run a length of 5/16" I.D. fuel injection hose (marked SAE 30R9, not the less heat-resistant old-fashioned 30R7 stuff that doesn't do well with modern gas formulations over time -- be sure to get fuel injection hose clamps, too). This line runs vertically up from the fuel pump, over the valve cover, and across to the carburetor. The fuel filter (with a metal can, the plastic ones sometimes don't do well with
oxygenated gas) gets installed vertically so it's right behind the
alternator...this keeps it away from heat and the alternator fan cools it
down further. Much better than the stock location where it gets heated up
by the exhaust manifold!

With this setup, a lot of the bitchy hot and cold start problems
disappear, because you're no longer boiling fuel in that metal line when you shut off the engine. Try it, you'll like it!
Sometimes 1920s just go "permanently bad" no matter what you do, often due to internal corrosion of the metering block ("economizer plate") that cannot be cleaned out or repaired. I once had a 1920 on my '65 D'Valiant that exhibited strange behavior: The engine ran very well and had fine power, but was suspiciously easy to start from cold (no choke required) and the car was getting under 10 mpg. Turned out the brass seat ring that retains the power valve ("Economizer valve") check ball, had fallen out of the metering block. The seat ring, check ball and check ball spring were sitting in the bottom of the float bowl. Result was that the power valve was always WIDE open. I put the metering valve back together and restaked the seat ring, but that carb never worked properly after that.
Careful here. There are two different floats for the 1920. They both look identical. One weighs 7.5g, and one weighs 12.5g. You have to use the correct float for your specific carburetor, or the magic stops working. Also, the float damping spring and float chamber baffle must be present, or badness will result.
Agreed. Makes me kinda wonder about your fuel pressure, but I've also seen this exact symptom set result from excess heat transfer into the pump-to-carb line, which is why I put "your first step" up at the top.
Wuh-oh, you already have done the flex fuel line mod?

Not normal.


Certainly could be. The castings are generally of decent quality, but they can crack, and sometimes they do.

Me, I'd replace that 1920 with a BBS Carter.

Welcome to the roaring Holley 1920's

The 1920 installed on Kermit, my '72 Valiant beater, is the only one I've ever been associated with that works well. It boils a little gas after hot soak, but not bad enough to flood the engine, just get that damn gas smell every time you turn it off. Also, no matter what pump diaphragm I try, or how true I make the warped metering body, gas seeps out around the accel pump arm on the back side. I have pretty much come to accept this.

I did try a BBS from a '70 198. It was a good looking carb, unmolested, great throttle shaft etc, seemed to be an excellent rebuild candidate. I freshened it and installed it on Kermit. Although Kermit actually seemed to run better on the road (if that's possible) with the BBS, The carb would completely boil over after the least little hot soak and flood the engine. Also, I never got the choke and choke pulloff adjustments where I needed them for good cold startup and warm up drivability. This is one area where Kermit's 1920 performs almost flawlessly, you'd think Kermit had fuel injection during warmup. I later found by checking my parts manual that a BBS and a 1920 call for different choke thermostats, so that could explain the warmup problem. I tried different float settings on the BBS, etc, but ultimately I didn't feel like dealing with the boil over problem, so I reverted back to the 1920. All I can figure is that the holley has a higher needle/seat pressure, perhaps because of the damper spring underneath it.

I would like to run the BBS. I am open to advice (but please, no dissertations on carburetor operation, I'm well aware of all the basics ). I plan to change the fuel line routing, but I wonder why this particular BBS is so much more inclined to boil over than the 1920, all else being equal, at least in this case... Thoughts?

D/W

_________________

If it ain't broke, fix it!

DW-

Sounds like your particular BBS has the wrong inlet fitting gasket. Yes, it really matters! You have to run the thin rubber-coated aluminum gasket, not the earlier thick (often red) "cardboard" gasket, or this kind of problem can result.

Also make sure the bowl vent is working correctly. The '70-'71 BBS had an odd sort of secondary bowl vent lever "piggybacked" atop the accelerator pump lever, and if it's not adjusted right and the bowl vent doesn't open correctly/reliably, this kind of problem can result.

On that subject, make sure your charcoal cannister is hooked up all the way correctly, if you're still running it.

Finally, quality on the inlet needle/seats has been spotty over the years; you may need to try a few until you get one that works nicely.

And yeah, you want to run the correct choke thermostat and do the fuel line relocation deal.

It's possible. I'll check. Float was set to spec (then I tried a bunch of other settings to no avail), but if the tab on the float is over-angled by the wrong gasket on the seat, I see where this could cause a problem.
The canister is moot because I don't have it hooked up. The bowl vent is not set up for the canister, it is the older style that vents to the atmosphere with a little cover and a clip on the pump "rod" itself. All set to spec, definitely venting adequately.

Thanks for the input. I'll check the gasket and try to optimize the needle/seat.

D/W

_________________

If it ain't broke, fix it!

Thanks for the replies

1. Yes, I converted the fuel line. Found out it is awesome for moving the carb so a catch pan can be used. No more mess when pulling the bowl!!

2. Pulling the PVC line kills the engine right now.

3. The float (Standard FL93) is a 7.5 oz. btw, the Echlin float you get is for a 2 bbl Holley. The application book merges them into one pn. However the correct numbers are still listed in the illustration catalog, but are no longer available

I am very suspicious of the econ plate area, since it seals off the passages that feed the discharge. If fuel leaks somewhere, then gravity will let it siphon out the discharge. After all, theres a reason why the jet is lower than the discharge. Just for grins, I may live very dangerously and put a super thin coat of hylomar on the body gasket and see what happens.

Its this very issue that will kill off slant 6s for everyday driving. Sure wish Edelbrock would start making brand new 1 barrels for these type applications!

For brand-new one barrels, consult eBay... You'd be amazed how cheap you can get an NOS one barrel for, there is little demand, which is why no one's ever going to make new ones. (I'll curse the day I let this secret out of the bag ) I'm just too cheap to get one.

By the way, the whole holley side-fuel-bowl-cheesy-rubber-diaphragm-gaskets-below-float-level philosophy of the sixties is why they suck so bad (including and especially the 4150/60 four barrels)

D/W

_________________

If it ain't broke, fix it!

Sorry to hijack your post a little, KenG, but it is related and educational
It turns out that the gasket is neither, it is a small thin black gasket approximately .030" thick. Not as thin as the coated aluminum gasket you cited, Dan, but I seriously doubt this could make the difference. Any other ideas?

I do seem to remember that I had to significantly bend the float tab to get the right float level - could the seat supplied in the kit need the thick red gasket??

Thanks,
D/W

_________________

If it ain't broke, fix it!

Thats OK.

Dennis

Did you remove the heat riser? /6s work different that V8s in that the riser actually shields the intake floor after warmup.

I find we are way beyond the shop manual and are tuning the cars to our local conditions.


I alos agree, Hollys are barely tolerable for high performance, I'd prefer Carter stuff anyday. On a side note I know of a drag racer in Ohio that runs AFBs on a tunnel ram and consistently blows away cars with single Holleys.

Negative. We've been all over that one in a previous thread, and you are 100% correct.

D/W

_________________

If it ain't broke, fix it!

H'm. That should not happen. Suggests major "issues" with the carburetor.
Yuck. I suspect the 12.5g float (not oz...a 7.5oz float would weigh almost half a pound...) is still available from Holley, but it'd probably be a great big special-order hassle.
...I'm not sure I understand your thinking here. Even if your existing carburetor cannot be made to work properly, there are lots and lots of compatible 1bbls out there that can, and with some more work, plenty of 2bbls.

One thing that has not been discussed is the needle / seat condition.
You most likely replaced it with a new one from a kit but pull it out and talk a super close look at it.
Any defects in the brass sealing surface or on the rubber tipped needle surface will cause a slow migration of fuel into the float bowl after shut-off.

I have seen light machining marks (chatter) on the brass seat and / or a tiny speck of dirt imbedded on the rubber sealing tip, this will cause these problems.

Remember that there is 3-7 lbs of fuel pressure "stacked-up" aganst that valve after shut down, that fuel wants to get into the carb.
Because of this, and the lower evap. point fuels, we have a situation that can really "stink-up" the engine bay and cause problems during hot restart.
What happens is that the fuel starts to boil-off, makes vapor that goes every direction. As that fuel boils-off, the float / needle lets more in, more boils-off, more comes-in...., until all the "head pressure" is off the needle valve.

Things to help this is to insulate the carb using a thick gasket and a heat shield. The other "fix" is to use a pressure return line, back to the fuel tank. Upon shut-off this system will bleed-off all the pressure on the backside of the needle valve so new fuel will not be introduce into the carb., as the gas in the carb boils-off.
DD

I'll recheck the needle.

I goofed and met grams. lol, ounces would be sorta heavy eh?

As far as keeping slant six stuff going, what I meant was the constant carb issues will mean only hard core gearheads/tinkerers will be able to keep one going. Around here what few /6s that appear in the boneyard always have no carbs and cracked exhaust manifolds. These engines will just get worse. I deal with parts a lot, and a lot of stuff like specific choke coils, carb floats etc are being discontinued. Rebuilt carbs are iffy since the cores are getting more and more worn out. Sort of sad if you ask me

Hi there Ken

1920's have one big drawback: you can't access the passages inside the main body if you don't unplug some brass or lead crimped or riveted plugs.

The issue you're describing is due to many sub-problems (IMHO)

1) idle circuit clogged
2) the checkball on the "valvlebody" (metering block) nd its corresponding duct may be dirty or clogged
3) Idle/power pump are separated by one tiny steel ball and some sort of brass counterweight. If you shake the carb main body (w/o any accesories that might vibrate) do you hear noise? like shaking some spraypaint can? if not, you might need to remove one brass cap and one riveted lead pig on the "passg side" of the carb. The lead pig is pinted to the accel pump jet, the brass cap to the bottom of the fuel bowl. Accel pump jet should be 0.026" nd you can add some thousands for improving take offs.
4) the idle air jet is partially clogged or dirty at least. And the main jaet circuit air jet may be poor too. Those are located in the venturi, right below the fuel bowl vent (where it sputters gas when hot). The "big" hole (on the left, looking at the carb with fuel bowl facing the floor and air cleaner side facing your face) is the idle circuit air provider. It should be 0.070" give or take only a few thousands. If this hole has been reamed for cleaning purposes and is way out of size (bigger) your idle screw is gonna be pretty much inoperant. The smaller hole on the right side is the main circuit air jet. It should measure 0.025" If you want to add some extra power at expese of gas mileage, of course, you can enlarge this up to 0.040" increasing the size of the fuel jet accordingly to your new ait jet
size. 0.040" likes a #70 or up main jet, but it will kill your mileage. You gonna get nice throttle response and power, though.

I clean my 1 barrel holleys in a phenol based desinfectant. It dillutes in water. I dunno if you can get phenol based desinfectants up there. I work with my carbs this way: I soak the metering block and main body in premium paint thinner for 20 min, then rinse in hot water and then dry with compressed air. Then I soak it again in tholuene (is that right? the word in spanish is tolueno) for 20 min and rinse & dry again, then i soak it in that phenol thing for 2 to 3 hours, I rinse it in boiling water and blow generoulsy thru all the holes with compressed air. Then I visually inspect all the ducts I can see and deburr any dirt outta those places. If you're to open up some ducts, you must do it before all the soaking. If you need to close those ducts, you can choose between old fashioned lead pigs and brass caps, or go to some new material such as grilon or delrin, or be fancy machinistically and plug those ducts with brass screws and soft aluminium washers (you're to tap the main body)

Float should have a 15/64" clearance.

Hopefully if you get into this much trouble, the next time you'll need to overhaul again your 1920 will be in 15 years or more if you clean the carb on a regular basis.

_________________
Juan Ignacio Caino

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