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Re: re bushing a carb shaft
[Re: DEMONSIZZLER]
#525066
11/13/09 05:09 PM
11/13/09 05:09 PM
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Joined: Jan 2004
Posts: 5,476
340dart4spd
OP
Parts Problem
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OP
Parts Problem
Joined: Jan 2004
Posts: 5,476
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Quote:
I will give it a try!
The first thing you have to do is get a special ream that is a 'twist style'. It has to be the same size as the shaft diam. of the shaft to be bushed.
Then you need to de-stake or grind off the end of the butterfly screws opposite end of the head of the screw. Usually a Dremel with a thick cutting wheel will do and you only have to grind to the od of the shaft. Remove the primary to 2ndary link if applicable.
Then you have to remove the screws, the shaft/spring assembly and any levers at the passenger side of the shaft end as needed.
It is best to clamp the carb or base in a vise so that the shaft bore is vertical, then use the ream and insert it into the bore. You should 'mark' the ream with a black indelible ink pin at the beginning of the bore id closest to the ream and only ream about 5/16" to 3/8".
Then you will need an appropriate bushing to do the job. I make my own on an old WWII South Bend lathe and had fit and clearance the id with the shaft from the carb. I also steak the bushing after installation to the outside.
Last is the re-installation of the shaft, the spring tension and either re-steak the new butterfly screws or use new screws and Locktite and an external star washer under the head of the screw. **Before you thghten the screws for good, align the butterflies so that the front edge shows the same about of idle transfer on each butterfly as the throttle is moved to wide open throttle.
It is not the easiest task to do but if you have decent mechanical skills with tools, you can do it with the right parts, David.
so my next question is... how much play is acceptable if any?
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Re: re bushing a carb shaft
[Re: minivan]
#525069
11/13/09 07:32 PM
11/13/09 07:32 PM
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Joined: Jan 2003
Posts: 826
Stone Mt, GA.
DEMONSIZZLER
super gas
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super gas
Joined: Jan 2003
Posts: 826
Stone Mt, GA.
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Quote:
Do you normally only have to do the primary throttle shaft and NOT the secondary..
The 2ndary shaft does not take the abuse the primary shaft does. The wear is generally a result of the amount of use the primary shaft gets and the return spring tension. The net result is that the primary bore on the throttle lever side 'elongates' over time. The new bushing corrects this.
The 2ndary bore gets a little loose sometimes but since it does not have an idle circuit(unless it happens to be a 4 corner idle system like Holley double pumpers), you do not need to bush unless the 2ndary butterflies do not close completely.
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Re: re bushing a carb shaft
[Re: DEMONSIZZLER]
#525070
11/13/09 09:34 PM
11/13/09 09:34 PM
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Joined: Jan 2004
Posts: 9,066
Eugene, Oregon
minivan
master
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master
Joined: Jan 2004
Posts: 9,066
Eugene, Oregon
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Quote:
Quote:
Do you normally only have to do the primary throttle shaft and NOT the secondary..
The 2ndary shaft does not take the abuse the primary shaft does. The wear is generally a result of the amount of use the primary shaft gets and the return spring tension. The net result is that the primary bore on the throttle lever side 'elongates' over time. The new bushing corrects this.
Does the shaft itself ever wear out?? I gotta assume the hole in the carb body is much softer but I "gots tu know"....
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