AMC86Kid Posted July 14, 2020 Share Posted July 14, 2020 ok guys I'm trying to tune my carb i got the timing down to around 13 BTD at around 700 rpm but now I'm trying to tune the carb and I'm trying to understand the correct way to do it also the motor operational temp is around 180-190 does anyone have any tips or a link to a good video Link to comment Share on other sites More sharing options...
Eagle Posted July 14, 2020 Share Posted July 14, 2020 What you need to know is in item 3 of the instructions you posted. You're looking for the leanest setting that allows for a smooth idle. You start at the baseline setting and turn the screw in (which makes the mixture leaner) until the engine starts to stumble, or run rough. That's the point when it's too lean. Then back it out just enough to smooth it out, and walk away happy. You have two idle mix screws, I believe, so turn them both equal amounts, to keep both sides of the engine at the same mixture. In the old days, we used an idle tachometer for this -- sometimes you would see the RPM change before you could hear a difference in how smoothly or how rough the engine was operating. Link to comment Share on other sites More sharing options...
AMC86Kid Posted July 16, 2020 Author Share Posted July 16, 2020 Ok so both front and back screw have to be turned the same amount so I got to change my current settings then cause right now there not even and screwing it in sends less gas threw right ? Link to comment Share on other sites More sharing options...
Eagle Posted July 16, 2020 Share Posted July 16, 2020 2 hours ago, AMC86Kid said: Ok so both front and back screw have to be turned the same amount so I got to change my current settings then cause right now there not even and screwing it in sends less gas threw right ? Correct -- in is lean, out is rich. The name of the game is to find best lean idle. That's why they tell you to back it out one full turn from seated, and then start adjusting by turning it in 1/8 of a turn at a time until the engine starts to run rough or stumble. When you get the stumble ... it's too lean, so then you back it out 1/8 of a turn at a time (both screws) until it idles smooth again. If you have an idle tachometer, hook it up and watch for then the RPMs start to drop off and/or the RPMs start to jump around. Link to comment Share on other sites More sharing options...
AMC86Kid Posted July 18, 2020 Author Share Posted July 18, 2020 Ok I think I set it good now both screws are fully turned in and then backed out 1 and 3/4 of a turn and my idle is around 800 I think I’m good now, I might just have to reset the timing now to see if that makes a difference Link to comment Share on other sites More sharing options...
Eagle Posted July 21, 2020 Share Posted July 21, 2020 On 7/18/2020 at 5:04 PM, AMC86Kid said: Ok I think I set it good now both screws are fully turned in and then backed out 1 and 3/4 of a turn and my idle is around 800 I think I’m good now, I might just have to reset the timing now to see if that makes a difference That doesn't sound right. The instructions say to start with the screws out 1 turn, and then turn them IN 1/8 turn at a time. How did you get to 1-3/4 turns out? That may be very rich. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted July 22, 2020 Share Posted July 22, 2020 I’ve tuned those carbs it’s easy to get wrong. I followed the instructions exactly and got it to run smooth and not too rich. Looking back most of the time we adjusted the new carbs Holley and Webber it was unnecessary where we live basically at sea level. My old 2.8 xj had the high altitude set up and the carb needed to be set up differently out in the mountains and high desert. Living again at sea level I left the new Weber at factory settings. Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
AMC86Kid Posted July 22, 2020 Author Share Posted July 22, 2020 If I start it at just one turn out then it won’t stay at idle and die off Link to comment Share on other sites More sharing options...
Eagle Posted July 23, 2020 Share Posted July 23, 2020 18 hours ago, AMC86Kid said: If I start it at just one turn out then it won’t stay at idle and die off Read note #5 in the instructions. Link to comment Share on other sites More sharing options...
AMC86Kid Posted July 25, 2020 Author Share Posted July 25, 2020 Yeah I know but I’m not gonna mess with that at this point I just need to pass emissions with the truck first Link to comment Share on other sites More sharing options...
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