1968 Newport Carter 2bbl carb.. I rebuilt and now it idles way too fast HELP

MBar

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Car was running pretty good but bogging when I stepped on it. I saw the pump was only squirting into the left horn. Gaskets were toast so I did a rebuild. The only snag was when I dis-assembled the StepUp assemby (with the metering rods), there was a piece of seal or gasket stuck on the spring. The kit diagram shows a gasket (31) but the piece that was on the spring was thicker than the o-ring style shown on the drawing. Below is a pic of the parts. There was a piece in the kit that seamed to match but looked like cork. When I tried that, it seated nicely and didnt catch on the spring. Yet another piece seemed to fit the cylinder end but wouldn't fit in the hole easily. The o-ring went in ok but immediately caught the spring. The closest video on YouTube showed one guy not putting anything and another guy using the o-ring. The original was obviously done so I don't know what difference it makes. I was most comfortable with th e cork piece as it stayed and seemed to match the original piece but my concern was that the cylinder didn't go down as far with that in place. In the end, I left it out and finished the carb.

I started the car and it runs smooth but much too fast on the idle. I see what seems like an idle screw but it doesn't come near to a surface to make a difference(that seems strange) I just don't see any adjustment beside that screw. I checked the linkages and any sources of binding.... even disconnected the pump and the choke. Seems as though the throttle just doesn't go to a low idle even if I push to the farthest. I did note that when I was re-assembling the throttle body, the butterflies don't close all the way (maybe 1/8th to 1/4 inch open) but assumed that is normal. When I reference pics, everything looks the same as before. I know the mixture ports are sealed. The air bleed screw on the back doesn't make any difference.

It seems this is a Carter ABD according to the tag 4578s and all the info I can find is for BBD. Looks like tons of versions all very similar.

HELP PLEASE :)

carb3.jpg


carb2.jpg


carb1.jpg
 
Throttle plate should close all the way. Take it back off and determine what is causing this condition. Usually it will be a problem with an improperly installed linkage on the fast idle cam or a fast idle cam that is stuck in the deployed position. Could also be a throttle cable that is set too short and holding the plate open. Also check to be sure the base plate gasket is not in conflict with the butter fly.

Dave
 
Throttle plate should close all the way. Take it back off and determine what is causing this condition. Usually it will be a problem with an improperly installed linkage on the fast idle cam or a fast idle cam that is stuck in the deployed position. Could also be a throttle cable that is set too short and holding the plate open. Also check to be sure the base plate gasket is not in conflict with the butter fly.

Dave
Thanks Dave! Pulling it now and gonno put up some pics... trying to beat the rain :)
 
Throttle plate should close all the way. Take it back off and determine what is causing this condition. Usually it will be a problem with an improperly installed linkage on the fast idle cam or a fast idle cam that is stuck in the deployed position. Could also be a throttle cable that is set too short and holding the plate open. Also check to be sure the base plate gasket is not in conflict with the butter fly.

Dave
Hooray for Dave!!! Thank you for the tip and especially for responding so quickly :)
I pulled the carb and sure enough, the plates were not completely closed as in the first pic below... I loosened the screws (notice the brass 6/32 I modified because I lost one!) and moved the shaft back and forth and the plates seated all the way and then I tightened back up... worked like a charm!! Idles nice now...

Throttle open.jpg


throttle closed.jpg
 
The throttle plates on my 2 BBDs are all a bit off. I got the pair on the 1971 version to decently close, and ran it for a month or so before the Edelbrock upgrade. I understand this is a VERY common problem for the BBD....
 
The throttle plates on my 2 BBDs are all a bit off. I got the pair on the 1971 version to decently close, and ran it for a month or so before the Edelbrock upgrade. I understand this is a VERY common problem for the BBD....
Yup... They were fine until I took it all apart... Good now and lesson learned..
 
I don't believe I've ever seen a cross-hatch pattern on the throttle plates like that before.
 
I wonder if it makes a difference... swirls the air? IDK....

More likely its there to reinforce the flimsy little plates by giving them marginally greater thickness on the lines of the pattern. I got the '71 to STAY TOGETHER by using a bit of blue threadlock on the screws holding the air horn onto the base. NOT a good design, how those were done. While all 3 of the 2 barrel carburetors used by Mopar on their big block engines were prone to air horn warp due in part to over-eager, underbrained owners over-tightening the breather nut, the BBD is the one Carter carb I don't tout. They were meant to be disposable, and should be.
 
You may want to put locktite on the screws or peen the ends over so they don't back out. Why did you remove them anyway, throttle shaft bushings?
 
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