Carb shaft and bushings what's the latest?

Tech tips and how to's

Moderators: garth, notoptoy, S Allen

111jag
Roadster Fanatic
Posts: 91
Joined: Mon Sep 28, 2015 12:58 pm

Carb shaft and bushings what's the latest?

Post by 111jag »

Ok having carb issues. I think it may be a worn throttle shaft. Haven't had the opportunity to look at it just yet. Plan on doing it in the spring. Has anybody put in new bushings and throttle shafts themselves? Did you use brass bushings? How about sintered bronze? Has anybody used Delrin as it wears far better and doesn't wear the shafts as much as metal to metal? How about graphite impregnated fiber bushings?They don't cut shafts and they tolerate vibration and they need no lube since it's built in. Some companies use a genuine sealed ball bearing but for the price I'd buy a new engine. Saw Joe Curto's (the carb guru) video and it doesn't look hard to do. The reason I'm asking is because I'm thinking of doing this myself. Has anybody purchased a reamer, bushings and from where? Not even sure of the size as I haven't researched that yet? I'm new to all of this carb stuff, but I am learning.

User avatar
keith0alan
Roadsteraholic
Posts: 812
Joined: Wed Sep 22, 2004 10:07 am

Re: Carb shaft and bushings what's the latest?

Post by keith0alan »

I did some delrin and they didn't work so well. The coefficient of expansion of the delrin was too high and the bushings got tight as the carbs warmed up. Coefficient of expansion is the big player in picking materials. I have done many oilite bronze bushings. Having a lathe is very handy but not vital. I turn the old throttle shafts to remove wear then ream the bushing to match. With new shafts the bushing part could be done on a drill press. A number of different bushing materials should work but I have yet to see one of my oilite bronze bushings wear out. A number of the British SU carbs have bushings that are designed to be replaced easily. The roadster ones are not designed to be field serviceable.

111jag
Roadster Fanatic
Posts: 91
Joined: Mon Sep 28, 2015 12:58 pm

Re: Carb shaft and bushings what's the latest?

Post by 111jag »

Did you use a reamer or regular drill bit in your drill press?What size with what size of bushing? I guess it depends on how much you turn the shaft?

111jag
Roadster Fanatic
Posts: 91
Joined: Mon Sep 28, 2015 12:58 pm

Re: Carb shaft and bushings what's the latest?

Post by 111jag »

I just took the carb off my car. At closer inspection I am not sure if the play in the carb throttle shaft is great enough to replace? Not sure how much is too much? Maybe someone can tell me by looking at this video:( ) Also, being new to all of this carb stuff, I thought the Hitachi SU carb did not have a bushing in it? As you can see from the video, they are there in mine. Looks like the original bolts on the throttle plate, so I am sure it is was not rebuilt.
Rob

JT68
Talented Enthusiast
Posts: 2107
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Carb shaft and bushings what's the latest?

Post by JT68 »

Yes, they are worn out. Any visible play is too much, otherwise you will have a vacuum leak (air WILL find a way). To do it correctly really requires some special tooling. Suggest you send it to Keith or someone set up to do this. NOT a British car guy. Hitachi's and brit carbs are visually similar, but nearly every detail is different. j
JT/LT
Datsunrestorationproducts.com
Only the best parts for your 311!

User avatar
Linda
Roadster Enthusiast
Posts: 7695
Joined: Sat Nov 05, 2005 11:37 pm
Location: Los Angeles
Model: 1500/1600
Year: High Windshield-68-70

Re: Carb shaft and bushings what's the latest?

Post by Linda »

I think that Z Therapy can do just that part of the carb for you, which is useful if the rest of the carb is good. Give them a call and see what they say.
Linda
68 1600 Los Angeles, CA
New owners must read: the ultimate road trip, by Scott- roadsterroadtrip.com-http://www.roadsterroadtrip.com/index.php/readfromstart

User avatar
jrusso07
Roadsteraholic
Posts: 1433
Joined: Sat Aug 02, 2008 9:02 am
Location: Penn Yan, NY
Model: 2000
Year: High Windshield-68-70

Re: Carb shaft and bushings what's the latest?

Post by jrusso07 »

Ztherapy will sell you completely rebuilt carbs or rebuild bodies with new throttle shafts. Need your old carbs or bodies for cores. https://www.ztherapy.com/products/maste ... e_list.htm. see ZT710 on the price list.

I ran a set of their rebuilds on my 240Z. Very nice carbs. I also run Keith Williams rebuild on two of my 2000s. Both run excellent!
Joe

1969 SRL311 - Solex
1970 SPL311 - U20 mod
1970 SRL311

User avatar
keith0alan
Roadsteraholic
Posts: 812
Joined: Wed Sep 22, 2004 10:07 am

Re: Carb shaft and bushings what's the latest?

Post by keith0alan »

That is a bit much play. Where throttle shaft play will cause problems is at idle. It high speed any leak is too small to make a noticeable difference. Those are the factory bushings. Some had them some didn't. The bushings are in a blind hole, you can't push them out. They need to be carefully drilled out without going all the way through. The British bushings are designed to be pushed out and replaced, Hitachi not so much. A complete refurbish takes me a long time because there is a lot involved and I am slow. If you send just the bodies with shafts in place I can bush the bodies and turn the throttle shafts within a couple weeks.

C.Costine
Roadster Nut-Site Supporter
Posts: 1364
Joined: Fri Feb 13, 2015 8:08 pm

Re: Carb shaft and bushings what's the latest?

Post by C.Costine »

I read on another forum about a test at idle by applying a dab of grease to the ends of the shafts to see if it makes a difference in running.
located in Chester NH
1967 1600 in restoration
2013 Arctic Cat F-1100 turbo
Ford F-350 6.0
Ford 9000 puller, Ford 960 puller, Ford 901show, Ford 971 worker, Oliver 70 waiting its turn

User avatar
notoptoy
Vendor-Site Supporter
Posts: 9351
Joined: Fri Oct 02, 2009 2:55 pm
Location: Winston-Salem, NC and Ocala, FL

Re: Carb shaft and bushings what's the latest?

Post by notoptoy »

C.Costine wrote:
Fri Feb 14, 2020 10:37 am
I read on another forum about a test at idle by applying a dab of grease to the ends of the shafts to see if it makes a difference in running.
You can check for the same effect if you use starter fluid or carb cleaner sprayed at the shaft ends while running.
"When all else fails, force prevails!" Ummm, we're gonna need a bigger hammer here.

67.5 SPL311 H20 w/5 speed
65 Impala Convertible
2017 C43 AMG