Anyone care to discuss Carter WCFBs?

[studiog]

1961 Vette 2x4 270HP As some of you may know I recently got my rebuilt 283 running and everything seems fine with that but I am having a terrible time with my rebuilt 2x4 carb setup. I am running on one carb now so I can trouble shoot one at a time. Here are the symptoms: After warm up it will maintain a high idle but the idle revs up slightly and then slows down then back up again and so on every couple of seconds in a steady beat. (Idles like my lawn mower) I can see the metering rods lift as the engine slows and the vacuum drops. Then with the rods lifted the idle picks up again, as the idle picks up the vacuum pulls the rods down into the jets and restricts fuel and the idle drops again. If it put my hand over a portion of the top of the carb it levels out to a steady smooth high idle. If I start to open the throttle part way it bogs down. If I open it most of the way it takes off and smooths out. Am I sucking air in somewhere? No vacuum ports are open, doesn't have a vacuum advance on dist. no pwr. brakes, no vacuum hoses at all. Any ideas? Thanks in advance for your replies guys.

 

[67HEAVEN]

studiog,

Try this link to carb troubleshooting.
http://www.recarbco.com/technical/smog/smoginfo.html

 

[studiog]

Thanks 67 and good luck with your motor. I'll be watching your site for updates. Is the moderating a new thing for you at CAC?

 

[John Mcgraw]

Sounds like it is running pretty lean. The giveaway is that it smooths up when you choke it a little with your hand. I would verify that your float level is set correctly before changing the jets and make sure that your accelerator pump is adjusted correctly. I take it that you have already adjusted the idle mixture adjustment screws?
Regards, John McGraw

 

[studiog]

Thanks John, everything is pointing to vacuum leak or lean running. This is very helpful.

 

[drags1998]

Well, Ill see if I can help without getting long winded? I thought only 1 of the carbs had an idle circuit. If this is so,make sure you dont have a vacume leak on the carb with no idle circuit. Meaning the butterflys must be FULLY CLOSED!!!! Also make sure there are no vacume leaks around the bases of the carbs. If you check the above & still have problems ,let me know,Paul:confused

 

[studiog]

Well, Ill see if I can help without getting long winded? I thought only 1 of the carbs had an idle circuit. If this is so,make sure you dont have a vacume leak on the carb with no idle circuit. Meaning the butterflys must be FULLY CLOSED!!!! Also make sure there are no vacume leaks around the bases of the carbs. If you check the above & still have problems ,let me know,Paul:confused

drags1998 Thanks. I keep hearing vacuum leak at carb base. I'll have to put that at the top of my list. Keep you posted.

 

[slider595]

studiog, see the attached site, the experts in carbs. the owner is a guy named John. Tell him Mark Banac told you to call him with questions.
http://www.ponycarburetors.com

 

[John Mcgraw]

I would suspect that you are correct about the Vacuum leak. One little trick you can use to verify, is to spray some WD40 around the carb base, and if it speeds up then you have a leak! I had a really bad carb sealing surface on the manufold of my 60 when I fired it up for the first time, and spent hours with a Bastard-cut file flattening the manifold. I just stuffed some paper towels tightly in the holes of the intake and vacuumed the filings out before I pulled them out.

Regards, John McGraw

 

[Tom Bryant]

Well, Ill see if I can help without getting long winded? I thought only 1 of the carbs had an idle circuit. If this is so,make sure you dont have a vacume leak on the carb with no idle circuit. Meaning the butterflys must be FULLY CLOSED!!!! Also make sure there are no vacume leaks around the bases of the carbs. If you check the above & still have problems ,let me know,Paul:confused

Paul,

These old 2x4 WCFB setups had idle circuits on both carbs and they were both supposed to be adjusted for best idle quality. :L

Anyway... review this recent thread for a few pics and discussion of this setup.

http://www.corvetteactioncenter.com/forums/showthread.php?t=44773

BTW It sounds like a vacuum leak to me too.

Tom

 

[studiog]

Update: I tested for leaks this morning on my carbs by spraying as John McGraw suggested, great idea and I have established that there are no leaks at the bases. I used starting fluid cause I had it handy and it evaporates off the manifold quickly (fire extinguisher close at hand). When I opened the throttle about 1/3 it starts to bog then I sprayed some of the starter fluid into the carb and it takes off smooth as glass for a few seconds. I am going to try John's other suggestion that the float may be low. I am pretty sure now that it is something with the carbs themselves. I am considering buying a new carb just to test it once and for all. Any recommendations for a carb or comments on this idea? Slider95, thanks for the info I will keep it in mind for later on.

 

[John Mcgraw]

The first thing you should do now that you have verified that you have no vacuum leak it to verify that the accelerator pump starts to shoot fuel with the slightest movement of the linkage. This can be adjusted by bending the linkage and adjusting the arm that is hidden under the little cover at the top of the carb.
I had one that drove me nuts for several days. I adjusted the pump linkage but it still had a lag in it due to the slop in the linkage and holes. I finally pulled it apart and found the carb restorer had left the spring from under the accelerator pump piston! The pump worked and returned when pulled back up by the linkage, but without the spring to take up the slack in the linkage, there was a hesitation in the actuation of the pump. The spring took all of the bog out of the initial acceleration.
Regards, John McGraw

 

[studiog]

Hi John,
I think my accelerator pump is working pretty well. I get some squirt even at the slightest amount of throttle and I don't see any lag. It runs the worst when I try to hold a steady part throttle. I am going to check the floats as you suggested earlier and see if the fuel level is too low.

 

[studiog]

I was able to borrow a known functioning carb and test my motor. It runs fine with the borrowed carb. Now I just need to find out what is wrong with my WCFB's. I have a Carter manual on the way so I will wait for that before I proceed. Still think John McGraw is right about the floats though.

 

[jose]

Hi

From experience on carbs when the motor picks up revs to around 1500 rpm and drops back down at a steady beat , I found the primary jets were blocked.
To clear them out easily take the air filter off, rev the motor and as the carbs are at full throdle completely block the carb throat causing it to flood therefore washing out any blockage.
Dont need to rev the motor too hard but make sure the throdle is fully open when you block the carb from the top.
Dont let it stall let it breath normaly just before it stops to clear the excess fuel out.
Try it a couple of times and good luck.

Jose

1961 Vette 2x4 270HP As some of you may know I recently got my rebuilt 283 running and everything seems fine with that but I am having a terrible time with my rebuilt 2x4 carb setup. I am running on one carb now so I can trouble shoot one at a time. Here are the symptoms: After warm up it will maintain a high idle but the idle revs up slightly and then slows down then back up again and so on every couple of seconds in a steady beat. (Idles like my lawn mower) I can see the metering rods lift as the engine slows and the vacuum drops. Then with the rods lifted the idle picks up again, as the idle picks up the vacuum pulls the rods down into the jets and restricts fuel and the idle drops again. If it put my hand over a portion of the top of the carb it levels out to a steady smooth high idle. If I start to open the throttle part way it bogs down. If I open it most of the way it takes off and smooths out. Am I sucking air in somewhere? No vacuum ports are open, doesn't have a vacuum advance on dist. no pwr. brakes, no vacuum hoses at all. Any ideas? Thanks in advance for your replies guys.

 

[studiog]

Hi

From experience on carbs when the motor picks up revs to around 1500 rpm and drops back down at a steady beat , I found the primary jets were blocked.
To clear them out easily take the air filter off, rev the motor and as the carbs are at full throdle completely block the carb throat causing it to flood therefore washing out any blockage.
Dont need to rev the motor too hard but make sure the throdle is fully open when you block the carb from the top.
Dont let it stall let it breath normaly just before it stops to clear the excess fuel out.
Try it a couple of times and good luck.

Jose

Hi Jose,
You are on the right track. I started another thread about my progess (I should have just continued this one). Anyway, I removed the metering rods completely and the motor ran very well but of course very rich. I am thinking that the rods and the jets are mismatched as it appears the rods are completely blocking off the fuel supply. I have recently had this carb apart and I don't see anything blocking the jets. Thanks for the tip.

 

[studiog]

Finally success. Today I replaced the primary jets in my 2X4 Carter WCFB carbs with much larger .113" & .116 jets from a kit for a Carter AFB made by Edelbrock. Found them at the local speed shop. The carbs run great now! May do a little more economy tuning when I get it on the road. Can't understand why someone would have used the wrong ones but I guess allot can happen in 40+years.

 

[John Mcgraw]

Studiog,
Glad you got it sorted out.
Regards, John McGraw

 

[studiog]

Studiog,
Glad you got it sorted out.
Regards, John McGraw

Thanks for your help John.