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Before and After I had my carburetor rebuilt.


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28 replies to this topic

#1 Alexx

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Posted 24 April 2004 - 11:59 PM

Before my carburetor was rebuilt, my 81 subaru would idle perfectly when cold for about 15 seconds, then it would start to hesitate and idle roughly. I discovered that 15 seconds was not enough time to do my errands so I was concerned.

Then one night the car kept shutting off, I would start the engine but it kept shutting down almost right away, over and over. I had to have the car towed.

After that experience I had my carburetor rebuilt by Roo Builders. The Carb Rebuild seems to be a job well done.

After installing the carburetor myself and not using anything but the sound of the engine idling as my guide, I adjusted the idle and the additional screw on the carburetor and set the timing where the car seemed to run best.

Now when I start the car cold, it feels like it's only running on 3 cylinders. The car now makes great sound effects when cold like it is about to give out. After about 2 to 3 minutes, something "kicks in" and suddenly the car runs quite nicely, much smoother than it did before the rebuild.

My pre-heater hose is missing, but I doubt that would cause this problem.

Any ideas?

Why would the car run smoothly for 15-20 seconds when cold before I had the carburetor rebuilt, and now that the carburetor has been rebuilt, run poorly when cold, and quite nicely when it has been running for two or three minutes.

I do plan on taking the car to a qualified mechanic in the next few days after I have installed the pre-heater hose. I was just wondering if someone had any hunches.

#2 GeneralDisorder

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Posted 25 April 2004 - 12:52 AM

That's pretty typical for Hitachi choke's. Seems that every time I take the carb apart, and put it back together again, it acts a little different. I haven't opened up a choke yet to see what the deal is, but likely your mechanic won't be able to do anything for you. Tell you to get the carb rebuilt again probably..... hehe

GD

#3 Alexx

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Posted 25 April 2004 - 12:59 AM

Interesting. It does sound like the choke is choking.

The other more grim possibility is as the engine warms up one of the cylinders begins firing. However, why did the car run smoothly for 15 seconds before the carb was rebuilt.

What would make the choke not work properly?

#4 GeneralDisorder

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Posted 25 April 2004 - 01:17 AM

It's not exactly the choke - it's another mechanism that is linked to it. There is a cold idle-up that's supposed to run the idle up to around 1500 RPM's (near as I can tell) till the engine warms up. In order to get into the choke housing, you have to drill out two rivets, and remove one screw. Inside I imagine you will find all the electric choke parts, and the idle up bits too. There is a rod that extends from the housing, down to the primary barel throttle shaft - you will see what I'm talking about if you take a look at the carb with the air filter housing removed.

What I can't figure out is why this mecanism *sometimes* works and sometimes does not. If I remove the top of the carb for other adjustments, sometimes it will just start working, and will continue to do so till I try to adjust the carb again, and then it stops. Or like right now - it will kick in a little bit if I hold the RPM's up for about 10 seconds when cold. Doesn't feel like it's fully engaging tho. I'll be dissasembling mine to inspect this mechanism soon. I'll try to remember to post what I find.....

GD

#5 GeneralDisorder

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Posted 25 April 2004 - 01:46 AM

I just had a chat with Mudrat about this, and apparently, you need to adjust the choke. if it's already been rebuilt, there's a good chance you don't have rivets, you have screws all the way around the choke housing. The bi-metal spring in the choke housing gets old, and out of adjustment. Apparently with the engine dead cold, you should set the choke so it is just barely closed after depressing the throttle fully one time. This should give you the high idle on a cold start..... worth a try at least eh?

GD

#6 Alexx

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Posted 25 April 2004 - 11:12 AM

Thanks for the info. What would I actually be adjusting and where is it located?

#7 Alexx

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Posted 26 April 2004 - 12:28 PM

Just thought I'd bump this.

#8 All_talk

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Posted 26 April 2004 - 05:16 PM

Adjusting a carb is a long process, especially an automatic choke as it can only be evaluated on cold start which usually means you make an adjustment and see how it works tomorrow morning. I’ve been through this on many carbs including the Hitachi on my ’87 GL Wagon. When I rebuilt it I took the time to check and set all adjustments as detail in the manual and it was very close right off the bat.

The rate that the choke opens is not adjustable (well not easily), it is a function of the supplied voltage and the resistance of the heating coil. What you adjust is the start position, “just closed” when dead cold is a good start. With the Hitachi I found that if you set closed enough for it to run smooth for the first few seconds on a cold morning it was a little to rich after the first 30 sec or so. I backed it off to run well in the middle of the choke cycle, a little lean at first start and ending up a bit rich just be for it full opened, a good compromise for most conditions.

The idle up speed is independently adjustable, again can be a bit of a compromise between blubbery the beginning and screaming at the end. There is a separate screw for it and its timing can be adjusted by bending the cam connecting link. And remember that taping the throttle while warming up will move the idle cam down to the next step as the spring lets it move.

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#9 Alexx

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Posted 26 June 2004 - 05:07 PM

Well, I passed my California Smog Test with flying colors! Thanks Roo Builders for rebuilding my carburetor. The only down side is the car really has trouble warming up because of the choke issue.

In California they don't allow the choke dial to be moved, it's actually riveted into position. I was told by a subaru dealership mechanic that years earlier there was a gentlemen in the Los Angeles area who actually was an expert at drilling out the rivets that hold the choke in place and readjusting the coil so that the car would warm up properly. He has since passed away.

So now I have a car that passes smog by plenty but is a son of a gun to start in the mornings.

#10 ThreeEyedBandit

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Posted 26 June 2004 - 08:28 PM

Are you going to meet everyone tonight? I will be there around 9:30 and will take a look at it if you want, if not you should show up just to join us and have a good time.

Matt

Also why are you passing cali. smog int oregon? just curious.

#11 Alexx

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Posted 26 June 2004 - 08:45 PM

Where is there?

#12 ThreeEyedBandit

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Posted 26 June 2004 - 08:49 PM

Where is there?


Sorry wrong Alex, I thought you were Alexc but you are Alexx, now everything make so much sence about the cali emissions. Again sorry for the confusion.

Matt

#13 Alexx

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Posted 26 June 2004 - 08:49 PM

Are you going to meet everyone tonight? I will be there around 9:30 and will take a look at it if you want, if not you should show up just to join us and have a good time.

Matt

Also why are you passing cali. smog int oregon? just curious.



I'm in Southern California!

#14 Alexx

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Posted 26 June 2004 - 08:52 PM

haha, our last posts came in at the exact same time.

Can you guys adjust your choke dial on Oregon Subarus?

#15 Caboobaroo

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Posted 26 June 2004 - 08:59 PM

I believe we can. I just rebuilt the carb on my gen 1 Brat and I can adjust the choke if I wanted to. Maybe you should get a carb thats NOT a Cali carb..... just an idea:D

#16 Alexx

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Posted 26 June 2004 - 10:39 PM

Well, since I passed smog with plenty to spare, I'd rather not tangle with the carb gods in the sky. Imagine if I switch and my readings go up and I fail anyway!

I think drilling out the rivets and replacing them with nuts and bolts may allow me the option to shift the choke dial. I know somebody who will take a look, but it won't be for a couple of weeks.

In the meantime, it will mean some really rough idling first thing in the morning until the car is warmed up.

#17 Alexx

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Posted 04 August 2004 - 06:05 PM

Final Update. I did not have the hoses put in correctly when I rehooked the car up. I had videotaped the carburetor and hoses before I disassembled it and sent it to Roo Builders in Colorado.

I since have discovered I made a couple of mistakes. Once the hoses were reconnected the car no longer rough idles. The only very minor issue is the car doesn't fast idle until warm.

A very minor issue for Southern California. The car runs great and I passed smog. Thanks Roo builders, the best $225.00 bucks I've ever spent.

#18 subGSR

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Posted 05 August 2004 - 03:38 AM

I replied to your other post about the carb problem.The mechanic I mentioned in that post managed to isolate the actual cause these carbs had.As far as I know after his rebuild there are no continuing problems, and the car runs perfect.

Before my carburetor was rebuilt, my 81 subaru would idle perfectly when cold for about 15 seconds, then it would start to hesitate and idle roughly. I discovered that 15 seconds was not enough time to do my errands so I was concerned.

Then one night the car kept shutting off, I would start the engine but it kept shutting down almost right away, over and over. I had to have the car towed.

After that experience I had my carburetor rebuilt by Roo Builders. The Carb Rebuild seems to be a job well done.

After installing the carburetor myself and not using anything but the sound of the engine idling as my guide, I adjusted the idle and the additional screw on the carburetor and set the timing where the car seemed to run best.

Now when I start the car cold, it feels like it's only running on 3 cylinders. The car now makes great sound effects when cold like it is about to give out. After about 2 to 3 minutes, something "kicks in" and suddenly the car runs quite nicely, much smoother than it did before the rebuild.

My pre-heater hose is missing, but I doubt that would cause this problem.

Any ideas?

Why would the car run smoothly for 15-20 seconds when cold before I had the carburetor rebuilt, and now that the carburetor has been rebuilt, run poorly when cold, and quite nicely when it has been running for two or three minutes.

I do plan on taking the car to a qualified mechanic in the next few days after I have installed the pre-heater hose. I was just wondering if someone had any hunches.



#19 spideyz

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Posted 05 August 2004 - 11:47 AM

After reading this thread, I am nervous to touch the carb in my brat. Hope I wont have to for a long time...:rolleyes:

Keith

#20 Alexx

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Posted 05 August 2004 - 12:07 PM

It Appears that Roo Builders has the rebuild down to a science. They put a custom fit brass fitting to eliminate the throttle shaft wobble. The key is to have a spare car so that the time it takes to rebuild your carb is tolerable.

#21 NV Zeno

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Posted 05 August 2004 - 02:35 PM

I've had a RooBuilders carb on my '83 for a couple of years now. I replaced the old one because of the throttle shaft problem mentioned above. Highly recommended rebuilders. Only problem is my fault: I've got two of the hoses hooked up wrong, hopefully someone at WCSS can identify which ones need to be switched so I can make the repair:-\ .

#22 GeneralDisorder

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Posted 05 August 2004 - 02:38 PM

Bushing the throttle shaft is a normal part of carb rebuilding - not something RooBuilders came up with just for the Subaru carbs. All carbs including the Weber's suffer primary throttle shaft wear, and must be rebushed eventually. RooBuilders sells throttle bases that have already been rebushed so you can rebuild the rest of the carb yourself if you want....

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#23 NV Zeno

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Posted 05 August 2004 - 02:45 PM

I just went for the complete package, don't have the patience to rebuild when a RTG is available for only a couple hundred bucks.

Badda-bing...done.

#24 GeneralDisorder

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Posted 05 August 2004 - 02:57 PM

Doing the rebuild yourself only costs about $35 for the kit, and takes an extra hour or two. My time is certainly worth a couple hundred bucks, and I suspect yours is as well.... if it wasn't you wouldn't be driving a carbed soob. The time it takes to ship it, and get it back is more inconveinent than just doing the rebuild myself - not to mention having to drive something else while I wait for it. I can order all the parts, wait for them to arrive, and then do the entire job in an afternoon after work.... and drive to work the next day.

GD

#25 Alexx

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Posted 13 November 2004 - 12:31 AM

It's interesting how some people think rebuilding a carburetor is like putting a quarter in a gumball machine and others (like myself) think it's like rocket science.

I would say that if one doesn't understand what all the parts do, rebuilding the carb oneself probably isn't worth it. The carburetor works really well now. The only thing left is to perhaps get the fast idle to work when the engine is first turned on in the morning.

How hard is that fix?




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