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199 Model 1931 Carb Questions

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Heavy 488 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/05/2019 at 11:13am
Look on the choke side of the throttle shaft. Any possibility that the lever got flipped over on the wrong side of the fast idle cam.
With the engine off, move the throttle all the way by hand. Watch the fast idle cam. Is anything interfering with it to bump it or is the choke itself pulling on it.


Edited by Heavy 488 - Aug/05/2019 at 12:06pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fisherwerke Quote  Post ReplyReply Direct Link To This Post Posted: Aug/05/2019 at 8:30pm
Nothing that I can see is interfering. I had some leaks to take care of and have to install the recored heater core tomorrow night. Then I can try to start it and tune it again
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/05/2019 at 9:44pm
i assume that it does this after the engine is totally warmed up, and looking down the throat of the carb, the choke plate is open all the way? if that is NOT the case, then the choke is probably just set wrong.


what's funny here is just today i installed a "new" Holley 1931 from rockauto.com on a 1968 American with 199ci. the one i pulled off had a throttle return spring built-in, on the "front" of the throttle shaft, under the bowl. the replacement does not, and relies on the return spring that pulls from the bracket bolted to the manifold.

the return spring that was on the car was too weak to actually close the throttle all the way; it didn't overcome the spring tension in the accell pump. i much prefer carbs thatr have a built-in return spring, for safety.

(i would have rebuilt my old 1931, but it's got the flat accellerator pump rod and there are literally no rebuild parts for it available.)


1961 roadster american, 195.6 OHV, T5
1968 american, 199ci, T96
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/05/2019 at 9:52pm
Then maybe like the last post referring to a choke adjjstment. When the engine is warm, see if the butterfly is somewhat firmly held open by the choke bimetallic spring. It may be slightly off allowing the choke mechanism to flip a little. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fisherwerke Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2019 at 9:49pm
Alright, Finally had a chance to get the heater core back in, everything reassembled, and rolled it outside to start it up. Pumped the pedal a couple times and she fired right up as usual but was idling very high. Bumped it off the fast idle cam and it died. Would not restart until the pedal/linkage was pushed and it bumped back up to the top of the fast idle. I played with the screw a little and it would run for a few seconds but then die. The only way it currently stays running is on fast idle.






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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fisherwerke Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2019 at 9:50pm
Originally posted by tomj tomj wrote:

i assume that it does this after the engine is totally warmed up, and looking down the throat of the carb, the choke plate is open all the way? if that is NOT the case, then the choke is probably just set wrong.


what's funny here is just today i installed a "new" Holley 1931 from rockauto.com on a 1968 American with 199ci. the one i pulled off had a throttle return spring built-in, on the "front" of the throttle shaft, under the bowl. the replacement does not, and relies on the return spring that pulls from the bracket bolted to the manifold.

the return spring that was on the car was too weak to actually close the throttle all the way; it didn't overcome the spring tension in the accell pump. i much prefer carbs thatr have a built-in return spring, for safety.

(i would have rebuilt my old 1931, but it's got the flat accellerator pump rod and there are literally no rebuild parts for it available.)



I missed this post..... I will have to take a look tomorrow night. Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2019 at 11:13am
If it won't run with idle air screw adjustment it seems to me like you have a vacuum leak coming from somewhere. 

I don't know this carb but normally the idle air screw gets turned out about a turn and a half and once running gets adjusted for max idle. When turning it in for the initial setting make sure you do not seat it hard, just touching. You don't want to deform the housing.

Make sure there are no open lines. 

Maybe the intake manifold gasket shrunk, but by tightening those could get you into more trouble if one or some of them break. I have removed two manifolds and can't remember breaking one so I would loosen first before re-tightening.

Maybe try blocking that PCV line temporarily. 

Some people say to spray something like carb cleaner around possible leak areas. If it speeds up then there is your leak. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/09/2019 at 1:06am
i can see from the top pic of OPs post that the fast idle cam is active, on highest idle speed.

if this is a new put of the box carb, it's got to be adjusted. it will not work out of the box.

make sure the idle MIXTURE screw is in whatever is the recommended startign position (lol, i'll do all this myself in a couple of days). GENTLY! with fingers! bottom the idle screw, back it out exactly two turns.

pull the hose off the distributor vacuum advance and plug it during the following. you must have ignition timing set right to start with. 5 degrees BTDC (even if the book says 0). timing interacts with idle mixture. it must be right!

let the car warm up though whatever means are necessary.

adjust the thermostat (bimetallic jobbie under the black disc on the rear of the carb) leaner, so it falls of the fast idle cam when you blip the throttle. you need to open it to take the tension off it. you definigetly do not want the choke activated on a warmed up car. in these initial setup phases, its OK to set it crazy-leran to essentially disable it, to get overything else working. then deal with it later. it's summer, you can get it to warm up somehow...

if the car stalls, turn the idle STOP screw in a couple of turns, start it, back it out till it starts to run crappy. you want engine RPM well under 1000, so that the idle MIXTURE screw is the sole source of fuel. if it's running at 1000, 1200, rpm, then its running on midrange circuits, not idle, and nothing will make sense.

if it just won't run at say 800 rpm, with the idle MIX screw out two turns, try 2.5, or 3. if it needs to be open more than that, you have a vacuum leak (or plugged carb, etc). dont proceed until this works.



assuming it will idle, even badly, 800 rpm or so, not on the fast-idle cam, and with the choke plate 100% open straight up and down....

turn the idle MIXTURE screw a quarter or half a turn, in or out, and wait a second to see what it does. it will speed up, or slow down. you want to use the idle MIXTURE screw to make the fastest idle speed, then the idle STOP screw to set the right idle speed.

when you get it close, the idle MIX screw should be sensitive; 1/8 or 1/4 turn makes a noticeable (50, 100 rpm) difference.

if the idle mix screw ends up out more than a couple turns -- richer -- you have an air leak somewhere. its adding fuel to accommodate the extra, unwanted air. stop and fix!

if the idle mix screw isn't out a full turn or more, there's an internal gas leak. this is less unlikely.


when all that's working, put the distributor vacuum advance hose back on. the idle ought to speed up again. (if not, see if the vacuum advance unit is leaking or stuck). adjust the idle STOP screw to set the idle to what you want, probably aroudn 600 rpm.




Edited by tomj - Aug/09/2019 at 1:13am
1961 roadster american, 195.6 OHV, T5
1968 american, 199ci, T96
sr-ix.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/11/2019 at 10:39pm
OK, you won't want to hear this but...

i too have a 68 american and the 1931 carb. i too bought a remain carb from Rockauto.com.

mine is total junk. the rebuild was an act of desperation on their part, assembled with the wrong parts and it doesn't work as shipped. its also quite unsafe.

here's the major flaws with mine:

* throttle shaft bore and/or throttle shaft worn to laughable state: i can easily stick a 0.032" wire between the shaft and the throttle shaft bore. it's so loose the linkage jams on the other end.

* assembled with the wrong throttle shaft; the replacement doesn/t have the built-in return spring on the non-working end of the shaft.

* the spring in the accellerator pump mechanism OPENS the throttle about 25%. it relies on the external return spring to fully close it. THIS IS UNSAFE. this is due to the lack of the return spring under the bowl.

* the bowl vent cap was missing.

* the choke unloader strikes the throttle lever, preventing it from fully closing the throttle plate. hence it "idles" about 1800 rpm.

* the throttle plate retaining screws were loose! and the throttle plate was cocked and also wouldn't close all the way. the loss of thos escrews down the manifold would nick pistons and bend valves, and the thottle would then be "wide open". THIS IS UNSAFE.

* throttle linkage (with all it's extra protuberances for other applications) was bent, causing the unloader striking above. clearly this wasn't tested at all.

* the idle mixture screw was corroded or buggered, and wouldn't set the idle, but with all the vacuum leak of the comically bad throttle shaft, it doesn't matter anyway.

i have photos and a video of the throttle shaft slop. no one competent would have stuck that together. it needs to be bushed, and it's not.


i'm sad swear words are blocked on this forum because they're all that apply to this carb. NO WAY i will ever use this rebuilder's junk again. (AutoLine from rockauto).

i agree it's a problem for this car. i'm not worried about originality, so i made a bracket to accept the twist throttle for an old Carter YF i've had around for 15 years or so. i think it's for a 72 Hornet.

it started, idled, adjusted right off. now i need to get a new air cleaner, it's a larger diameter opening, and the vacuum spigots are all different (i just plugged them).



ON TOP OF ALL THIS, and somewhat immaterial, the Holley 1931 is a crap carburetor, by construction design. bowl gaskets wet with gasoline are just stupid. yeah, i know better than Holley, as would any backyard mechanic. there's no reason for it, absolutely no advantage. and on an old carb, it's a fire hazard. the original 1931 on this car was seeping out the bottom of the bowl, slowly. it evaporares slowly, but when is dripping gas a good thing?

also it seems to have a very large bowl capacity; there's a lot of gasoline in there! by comparison a modern Weber has about one ounce of fuel in the bowl. this i'd just chalk up to old design, but coupled with the other deficiencies, it's just insult to injury.

no idea how well it operates. and i don't care. i'm throwing this one in the metal scrap pile and returning the "new" one to rockauto.

yeah i'm pissed off.

1961 roadster american, 195.6 OHV, T5
1968 american, 199ci, T96
sr-ix.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/11/2019 at 10:42pm

check out this throttle shaft wear! that's a length of 0.032" stainless steel safety wire. it's inserted 1/2", all the way into the bore!

how's that for AutoLine quality control?

1961 roadster american, 195.6 OHV, T5
1968 american, 199ci, T96
sr-ix.com

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