Wishin4a416 2,189 #1 Posted June 22, 2014 (edited) What size are screws on the butterfly to throttle shaft? Im thinkin 2-56. I have one gooned up on the 312 carb. Has anyone tapped these to 4-40? I came home from the show and she said she was mowing and it got real erratic. I checked and the shaft between the governor and throttle shaft was unhooked. The little plastic keeper is shot. But while doing this, I also found the the throttle was badly worn so rebushed it. And now I have messed up a screw. Edited June 22, 2014 by Wishin4a416 Share this post Link to post Share on other sites
Martin 2,130 #2 Posted June 22, 2014 (edited) Jack, 3-48 if my memory is correct. i bought some when i was doing some kohler carbs. i documented it in one of my build threads. i will look and see if i can find the info... this was on the earlier big block carter carbs. Edited June 22, 2014 by Martin Share this post Link to post Share on other sites
pacer 3,160 #3 Posted June 22, 2014 I just bought one of the "cheap" carbs off ebay and it came with the choke butterfly 'backward'. In trying to remove my original shaft to switch out one of the screws broke off (they are very fragile!!) - got the shaft out and after a bit of comparison, I found the original threads to be either 4-40 or VERY close to that. I just ran a 4-40 tap in the original holes and used button head 4-40's to attach. Share this post Link to post Share on other sites
Martin 2,130 #4 Posted June 22, 2014 the 3-48 was used on the carter 'n' carbs. the size i used to replace mine are 3-48 x 3/16. they were a perfect fit. if you check Brian Millers site he says the Walbro carbs used a 4-40. I've only messed with one Walbro (on my KT17) but never took much notice of the screw thread size. Jack, if you need a couple screws (3-48 variety), send me a pm and i will put some in an envelope and send you for the discount price of free...... Share this post Link to post Share on other sites
Wishin4a416 2,189 #5 Posted June 22, 2014 Thanks Martin. They definitely aren't 4-40 so they must be 3-48. I am going to check with the Bio-med guys at work tomorrow and see what they have. We don't have anything that small in my shop. I might take you up on your offer if no luck there. Share this post Link to post Share on other sites
Wishin4a416 2,189 #6 Posted June 24, 2014 Got a hundred comin from mac carr tomorrow for 4 bucks. Thanks Martin. 1 Share this post Link to post Share on other sites
Martin 2,130 #7 Posted June 24, 2014 Jack, i guess you will have plenty to use or give away like i do now!!! it is always nice to have spares though, i can't see myself going anywhere away from this hobby anytime soon....... 1 Share this post Link to post Share on other sites
