I am fixing a 72 Valiant for my daughter as her first car .It is a very nice example with a 225 and auto trans and ALL of it original equipment.This car did set for about 8 years before I bought it.
This is a list of what I have already done to the car,
1.manifold gaskets replaced
2.replaced cracked ex.manifold with good working unit from 79 Volare
3.Made sure manifold fit and does not leak
4.Did a GM HEI conversion using quality parts and set timing to 10*btdc
The inside of the engine looked good and clean like it was well maintained and all of the emissions remain intact and working and the valves have been set to .012 intake and .022 exaust until I can get the car out on the hiway and get it warmed enough to do a closer setting.
5.The gas tank was dropped and cleaned
6.fuel puump replaced with quality unit
7Car has a 109000 original miles and was a well maintained car throughout.
The problem is that after warming up(after choke has gone completey off) the car has a rough idle and the air/fuel screw does not seem to be sensative to changes but does seem to idle better when backed out 5 full turns or more but still does not have an acceptable idle.The Carb.the original Holley 1920 has been rebuilt Twice and looks like new.I used a Walker kit both times.
I seems as there is not enough fuel to let it idle well or like it has a vacumm leak but there is not,I have cleaned the carb with an initial dunk in carb cleaner(after dissassembly of course) and then with a careful cleaning with spray cleaner through all of the passages and careful reassembly and then thought that maybe I overlooked somthing and did the process again after the idle wasnt right.
The car runs great as soon as it is off idle and has plenty of power accelerates easily and quickly and will idle in gear but is rough and not acceptablr for a 16 year old girl to drive or anyone else for that matter.
I have read on the board that 1920 carbs can go bad and no amount of rebuilding can fix them,could somthing be stopping up the idle circuit and cause this?I really dont want to turn my Daughter off from old cars and having one that dont idle right is sure way to have start asking for a new Honda that I cant and wont afford.
I dont have any extra 1920s laying around but I do have a few 1945 Holley carbs that could be rebuilt to try.
Does this sound like a carb issue or am I off the mark?
BTW,I tried un hooking the emission controls and plugging them and the result was the same.
Any help on this issue would be a blessing and a boon to my daughter and mines relationship.
Thanks for your help
HyperValiant

PS I will answer any questions that will help get this problem resolved

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Sounds like you're pretty sure it's too lean. Just double check that...place a board or large rag (too large to get sucked down the carb) partially over the carb with it warm and running. If the idle speed drops, the idle smooths, etc., then you are lean.

Check for other obvious vacuum leaks, if you haven't already. I like to spray carb cleaner around the base of the carb, AROUND THE THROTTLE SHAFT, the intake, fittings, hoses, etc. Work the throttle linkage while spraying this area. Again, if the idle drops, you've found a leak.

Here are a pair of photos from the 1972 FSM. They show the "checking wet fuel level" procedure for the 1920. After a check for vacuum leaks, I'd start there. I've set them to the specs in the rebuild kits before, only to find the rebuild kit spec was wrong. Also had that fine adjustment get bent around during handling/reassembly, so it's possible it's off, leaving you too lean.





Hopefully one of these simple steps will help ID the problem.

As for a 1920 so worn out it couldn't be fixed/rebuilt, I have never personally seen that, in ANY model of carb. I've seen throttle shafts wear into the housing, creating a vacuum leak no rebuild kit (gaskets, seals and the like) can fix, but the carb can still be saved by having a machine shop bore the carb body out and add bushings for the shaft to ride on. Unless there's something special / peculiar about the 1920 that I've never seen, it should be savable. And if there is something unusual about the 1920 that wears out, I'd love to hear about it.[/img]

_________________
DynoDave
1970 Plymouth Duster
1972 Dodge Charger Rallye
1977 Chrysler Cordoba
WPC # 12304

Thanks Dave,Ihave already checked for Vacumm leaks but will check again and also check the level in the carb,as far as a 1920 going bad,I have read that the internal passages can be plugged up with old gas or shellaced gas and not be able to be removed no matter what you do,I will try your suggestions and have already done the shop rag over the carb opening thing and it did smooth out and that was what led me to beleive that the carb was lean.Thanka again.
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Hyper Valiant,

With my build, it too likes allot more fuel at idle. Some folks say a stock engine will run at 1.5 to 2.5 turns, but mine never did. I am running the idle screw out at about the same place. We have a good carb shop up here and one of the things they shared with me, is making sure the gasket that goes behind the economizer body isn't partially covering any of the holes when compressed, after the screws are tight. The fix for this is to punch the holes a little larger with a leather punch.

You can also take very fine piano wire or if your a fisherman, Monel (steel) leader material and fish through the holes in the carb body, plus spray them out with carb cleaner.

I brought back to life an old 1963 1920 Holley that I found sitting in a coffee can full of pine needles. It was white with oxidation from the aluminum. With some careful cleaning I fixed it up and ran it for about a year with #58 jet. So the tale you have heard about 1920's not being salvage able is not true.

I found a 1920 Economizer version and am running it at the moment. I love these carbs because they are so simple and perform so well. The only problem is if the shaft wears to the point where it needs to be rebushed to slow down the vacuum leak.

Check the vacuum canisters to be sure they are not leaking vacuum by capping all lines including the choke pull off. You may find a leak.

Leave the idle screw rich and maybe after driving the car for awhile it may idle better. My thought is that the valves are not as happy as the could be yet. There could be some carbon build up and your not getting the vacuum you need for it to idle nicely. After setting that many years it needs to go on a long drive.

I wouldn't waste any time on the 1945. I have several and they are a pain. They leak like in many places that the 1920 doesn't have.......

To give you some encouragement fixing the 1920, I have a 2.76 posi-traction rear-end with P235 60 14" Grand Am tires on my Dart. (they are made by Good Year and are soft, not hard like BF Goodrich T/A's). From a dead stop I can smoke both tires a fair distance to scare the heck out of most folks. So the little 1920 Holley can idle well and still make some power up to about 3000 rpm where it runs out of flow.

_________________
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

The caution about gaskets blocking passages is a good one. However:

Yes, it is true that the many blind/inaccessible passages in the 1920's metering block can (and eventually do) accumulate "potmetal mould" corrosion that cannot be cleaned out and blocks these passages, rendering the carburetor unrebuildable except by replacement with an uncorroded metering block, which sometimes solves the problem and sometimes doesn't. There are other difficult/impractical/impossible-to-fix failures that can occur with the metering block, and there is also the extremely tiny pinhole air bleed in the carburetor main body that can also cause essentially fatal problems.

No, the fuel (float) level is not causing your problem. If the float level were low enough to cause a lean idle condition, you'd have extremely lean running on acceleration, at cruise, and under wide open throttle.

Probing through passages with wires is a terrific and way to spoil a carburetor permanently. Those passages, and the holes through which they are accessed, are of very precise size. Any kind of physical reaming (as by pushing a wire through them) enlarges them. What is more, it scratches off whatever remains of the protective coating on the potmetal, guaranteeing that the "white death" corrosion will come back with a vicious vengeance, especially with today's alcohol-blended gasoline.

Needing to have the idle mixture screw open five turns confirms that either there is something the matter with your carburetor, or there is an undiagnosed vacuum leak elsewhere along the induction tract. You may want to try the blowout procedure described here, and also read through this thread.

The 1945 is less prone to fuel leakage than the 1920, because the 1945 hasn't got any fuel-sealing gaskets below fuel level, as the 1920 does. The 1945 has a bad reputation, primarily because they were all calibrated with top priority on emission control rather than good driveability. There are actually several fundamental design features of the 1945 that are advantageous, and they can be recalibrated to run well. Overall, which is better? Well...I'd take a 1920 in good condition over a 1945 in bad condition, but I'd take a 1945 in good condition over a 1920 in bad condition. I prefer a Carter BBS to either of them, but here again, at this late date, most of us are forced to pick carburetors by condition (or rebuildability) more than by brand and type.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan made some very good points!

So to clarify I used .020 monel wire so since it is so flexible and follows the passages easily. To keep the end form scraping any anodizing off the carb, I sanded the end of the wire round with 600 grit. Our local carb ship will re-anodize the carbs so there in no further oxidation.

Basically, with rebushing the throttle shaft and re-andozing a 1920 Holley can last just about forever.

_________________
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

The only real 'bad' design problem that shows up in the 1945 is almost like the Carter BBD, the lower plate/ throttle body can be warped or not be gasketed right and cause a phantom air leak right above the throttle plate. Unfortunately like all carbs, if they sit for too long they may not revive well (I have 3 Holley 1945's that sat/ got rebuilt/ wouldn't work/ rebuilt again/ still didn't work/ now are parts...same with 2 Holley 1920's and 2 Carter BBD's. Dan's made a good list of the essentials on these carbs...

Another thing to note, is the 1 barrel was meant to be used in a certain type of build/calibrated for a certain set of parameters, if you add more cam/ change the timing/ etc... you will have to change the carb to match these 'add ons'...

-D.Idiot

That reminds me...does the car have power brakes? If so, check that hose and booster.

_________________
DynoDave
1970 Plymouth Duster
1972 Dodge Charger Rallye
1977 Chrysler Cordoba
WPC # 12304

Thanks for all of the replys fellas.All of the parts are original to this car and it is completely stock except for the hei ignition,and does not have power brakes. As far as I can tell all of the areas that can vacuum leak are sealed well.The throttle shaft is actually very good on the 1920 and I found a good 1945 that I will rebuild.
Ted may have hit on a point that the car needs to be driven after sitting for so long,but as it stands it is not yet ready for my daughter to drive.
I am going to look at the links that Dan has provided and build the 1920 again also as I would like to keep this car as original as possible under the hood as well as keep all of the emission devices intact.I will try the 1945 that is off of a 76 Duster after a thorough cleaning and rebuild.
My goal for this car is to be a reliable and easy to drive automobile with an eye towards fuel mileage and low but proper maintenance.
Thanks again for the advice and replys,it is a true blessing to have the knowledge of so many people at your fingertips that are willing to help.Im sure that if the world were run like SlantSix.org it would be a better place.
Thanks
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Dan,I just read your links and I need to pay attention to those areas and double check them,that very well may a source of my problem.
Dan,you the Man
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Sorry, no.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Just about all 1920 carbs I have used ran way to lean for the engine. One good thing about the 1920 is the same jets that fit it are the same jets that work in the Holley four barrel carb that you see most racers use.



The higher the altitude you live the more jet they need. A number 58 jet seems to be a real good inbetween jet size that gives the best of power/economy balance. One of my 1920 had a 45 jet in it and it still ran best with a #58. Going on up to as high as #64 jet did give me more power but i would loose fuel milage. I live at 1500ft and that may give you alittle something to go by. You can go to most any perforance shop or even the Auto Zone and Advance Store may have jets, if not they can oreder them. If the carb runs fairly good except for to lean I would try the bigger jets. Many times something as simple as a little bigger exhaust or a muffler that allows the engine to breath a little more can bring on the need for bigger jets.


Ofcourse something being blocked or restricted needs to be atended to. When cleaning a carb buying the better carb spray such as Cum Cutter 2+2 will have a better chance of cleaning the passages out than the cheaper sprays will.

As I meantion thought I havnt found any 1920's that I used needed to raise the jet in size. Maybe its just my area that I live in that brings this on I am not sure. I put a lot of time into tuning my carbs and always try to get them working as lean as possible, but out side of the fact of starting to drill and resize other curcuits in the carb, jetting up is the only way I have been able to get the 1920 to no be crazy lean at idle. Soon I will go into the curcuits and start modifing them to give good A/F ratio's all the way across the board. Right now I waiting on some datalogging equipment before I take it to these extreeme's on the tuning. When I get my Mill wired I am even goingto try to build new metering blocks for them that will have changable bleads to help with tuning. There really great little carbs they just need a little help sometimes.



Jess

Other way round. It's a fuel jet, not an air jet, and the higher the altitude, the less dense the air, so the richer the mixture for any given volume of fuel, so the smaller the jet you need to achieve the correct fuel-air mixture. This was something I got very familiar with during my years in Denver (at 5500 feet above sea level).
The way I read the symptoms, we're dealing here with an idle problem. The main jet size has essentially no effect on the idle mixture, because of the low fuel flow rate at idle (the main jet size is not the limiting factor on fuel flow at idle — you'll get virtually the same amount of idle fuel from a #52 jet as from a #62 jet). Think of all those Holley 1920s in service with stock jet sizes and perfect idle...
The design of the metering block is really the 1920's downfall. Newly-designed blocks that are tunable and cleanable will help a lot! Argentina_slantsixer has done a fair amount of work in this direction, too.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan & Doc correctly led me thru a blocked air bleed testing & fix that had leaned out my 1920 causing irratic rough idle and low intake maniforld vacuum. It also didn't respond to changes in idle screw position

The carb was new but shelf worn with oxidation

See 65 225 Dart Valve Timing Chart

_________________
1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

any inexpensive ultrasonic cleaner will succesfully clean the blind passages in most 1920's metering blocks. Just don't use white spirits on an ultrasonic cleaner because it's dangerous. You can fill the little tub with glass cleaner, mild anti-grease detergent, etc. but nothing flammable.

Also, check on your idle air jet (larger one on top of the venturi, passg side if you're looking at the bowl from the front) stick a couple of brass wires (really thin gauge, strip any piece of multi filament wire and use say 2 of them) inside that "big" hole. If your idle smoothens out, you need a larger main fuel jet.

Maybe your power circuit is partially or completely clogged

BTW cleaning blind passages is a piece of cake. Just remove the plugs (brass plugs most of the time, sometimes you will find either lead or aluminum plugs too) beware of a little steel ball that might be inside the accel pump's passages, clean the carburetor with a good carb cleaner and replace them plugs with a dab of epoxy and a piece of aluminum rod, or a lead pig (hammer that in place) and you're good to go.

A properly tuned holley 1 barrel beats the crap out of BBS's.

_________________
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.