Won't idle w/o some choke

[rdean7]

I've been going thru carb and ignition for several weeks intermit, and for the life of me can't find a solution. Stromberg down draft carb. 

On first ride w wife.. lol.. the eng stalled at at a 4 way. After several restarts I realized the idle was in op but I could get home with throttle mgmt.

After cleaning carb only horn and middle body, nothing's really better. After warm, it needs 3/8 closed choke plate to idle yet a little hi. Less choke and it stumbles, too little it dies. 

I have adj the float from 1/4 to 5/8 from top edge. Changes choke required, but no fix. I assume it's lean wanting less air but smells rich in garage.

I also adj the idle screw from 1/4 to 3 out, slight change but no remedy. I have ign parts ordered but most are only 4 mos old. I do need to clean the points tho.

 

Ideas to check out?

 

 

[Robert Harrison]

its my understanding that if you can richen up the carb somehow and it runs better like this it is probably not the ignition.  You said you gave your wife the fires ride was that of the season?  Does than mean it has been sitting?  I'm guessing a port in the carb is plugged up by corrosion, or gunk. or a vacuum leak  Its critical to keep your gas tank full  especially the fall (and into winter) and run it somewhat regularly during those periods.  

 

Often people start playing around with other stuff and it can become a "if it aunt broke don't fix it" kind of thing as unknowingly another issue jumps into it like maybe you have a bad carb but you replace the ignition wires to see what happens but one of the new wires is defective.

 

I'd call Mikes carb (in Texas I think)  if you get on their site you can see how extensive their parts inventory is and maybe they can walk you through some questions with a vacuum gauge etc.  check filters but you probably did that and check fuel pressure.  Maybe check fuel pressure first

 

Since you probably can if you still have your old condenser try putting that back in I doubt it will make a difference but its so easy to try and the new or repro units have often been found to be defective.  Bob Harrison

 

 

[rdean7]

I put a carb kit in it from eBay. I did blow cleaner thru all jets and ports. It has a Daytona idle jet in it so supposed to have low float height.

As far as sitting you asked, I just bought it in Dec 23 and looks like ign tuneup was done but not the carb. New gas tank and E pump. I thought the pump was dieing after hot so I put a new E pump at tank and a new mech pump on the engine. I have a pressure gauge at the carb to monitor. Cold it's 6psi, looks to drop to 3psi when hot - even at 50 deg outside. 

 

It did idle when I bought it. It did not like the choke messed with to crank..even cold- liked 1/4 choke all the time. Now after rebuild it runs best at 1/2 choke plate at idle 900-1000 rpm. When driving it pulls best with choke open full.  It will bog at 1/4 to 1/2 open.. like normal.

 

New plugs, cap/rotor, points look new. No arching wires. 

 

Thx for any ideas here I may have missed.

Edited February 8 by rdean7
Sp

[Los_Control]

I'm still a little dazed and confused ..... down draft stromberg carb on a 1951 pilothouse?

 

As @Robert Harrison stated, when you richen the fuel by closing off the air .... you have a carb issue. ..... Typically I would direct you to the clogged idle circuit of your carburetor.

I know nothing of down draft carburetors, and if your 1951 pilothouse has them ..... this is a self inflicted wound.

[rdean7]

Well maybe a terminology issue here, I thought most carbs were down draft. Up draft is the weird one where the carb horn or opening is pointed downward so it has to pull air upward.

Anyway it is a Stromberg and the one with the dash pot rod. So yea I guess I'll be pulling it again to clean the throttle plate and air idle port.

I do hear noise from the fuel entering the carb throat. It sounds like the fuel is frying and hissing noises. 

 

 

Edited February 8 by rdean7

[Dave72dt]

what you have is a downdraft if the manifold is below the carburetor.   Updraft is below the manifold and side draft is horizontal.  Set you float to spec level according to the rebuild kit.  I suspect you have an incorrectly installed kit or a vacuum leak.

[Los_Control]

58 minutes ago, rdean7 said:

I do hear noise from the fuel entering the carb throat. It sounds like the fuel is frying and hissing noises. 

Kinda sounds like a vacuum leak .... sucking in extra air, ....  so closing the choke equals it out?

Spraying some carb cleaner around the carburetor base, throttle shafts etc would give you a hint if you have a leak ..... Also do you have vacuum windshield wipers?

A leaky hose from the manifold to the wiper motor could be a problem.

 

I have the Carter carburetor .... It uses 2 ball bearings to control the idle circuit iirc .... they are different sizes and easy to mix up .... no idea what the stromberg uses, never worked on them.

 

These motors when working properly are very quiet and boring .... air sucking sounds is a real clue and needs to be addressed.

 

My bad for confusing the down draft terminology, just never thought of a standard carburetor as a down draft before. Was thinking of a updraft.

[rdean7]

15 hours ago, Los_Control said:

Kinda sounds like a vacuum leak .... sucking in extra air, ....  so closing the choke equals it out?

 

I had tried this several times but no chg. I finally got a bump in idle around bottom of float bowl. 

I removed the top when oweshit hot and had air bubbles coming up in the bowl so I will have to replace all the copper washers again. 

 

Thanks for the help!

 

[rdean7]

Seems to be fixed now idleing at 550. The main issue i believe was fuel hose debris inside the Idle Air tube. Thinking of putting it in the ultrasonic cleaner to shiney it up.