As @chormy stated… For setting each carb air flow you need to separate the idle adjustment screws (acting on both carbs) by loosening the two clamps bolts on the butterfly linkage shafts (in between the carbs) and then setting carbs air flow individually with each idle adjustment screw until the carbs are individually balanced with the air flow meter. After balanced then tighten the two shaft bolts locking the butterfly shafts together again (with correct clearance on the forks). Then each carb idle will stop on both idle screws at the same time Otherwise the two shafts act as one and only the idle screw turned out the most will have any effect on the idle and it will adjust idle of both carbs at the same time. So you just chase your tail. Any idle adjustment down with this screw will stop when that screw position reaches the other idle screw position If you adjust the idle after balancing the carbs ensure both idle screws are in same postion so both stop the staft in same position. Ajust the one that changes the idle to desired revs then screw in other idle screw to same position to match that one. Look up ‘SU Carb balancing’ in plently of other videos or online manuals.
Thank you. I’m in the process of updating this video but I’m waiting on a part from a supplier so I don’t think I will be able to publish it for several weeks.
What a great video! the explanations, the shots, everything is great, really good job. Keep making content like this... also it really helped me with my Austin mini. Cheers from Chile :D
Extraordinary job! Much better to be long and detailed and then allow the viewer to skip parts if he/she wishes, than to do a short video with only highlights. Now if you could just make a similar video for HD carbs. Lots of commonalities though.
Yes, you are right. After reviewing the instructions and the video I think I now have too much free play in the cable/cam before the fast idle screws are engaged. As a result my fast idle is probably set incorrectly. I plan to make a carburetor re-build video this winter and as part of that I will be re-making this tune video. I have come to realize there are several small errors I made or pieces I left out that I should correct.
A friend of mine recently bought a '68 MGC and is beginning the process of getting it running correctly. I would like to know if the manual you refer to is readily available for purchase online anywhere. I think it would be a great gift :)
Great Video - Where /How can I get the SU Instructions you followed - I appreciate the depth and detail you went to in your video - this is what armatures need to do a professional job tuning SUs. Thank You!
Hi JR, I have a 68' MGC that when accelerating cannot get above 50 Miles per hour or so, the mechanic helping me thinks the rear carburetor needs to be rebuilt; do you agree & if so can I send the carbs to you for rebuild or can you recommend someone in the US? Interested in your thoughts? The mechanic is not comfortable rebuilding my MGC twin horizontal 1 3/4" SU's type HS6 carburetors. Thank you!
I appreciate the confidence but I'm far from a certified mechanic and wouldn't feel comfortable working on someone else's car. I would read through the post here: www.mgexp.com/forum/mga-forum.2/sucarbs-com-review.2488112/ They recommend a business that restores carbs called www.britishsuperior.com/
Thank you for the quick reply JR, am in Tulsa & have limited resources to work on the car's engine, the fellow helping me is great enough to tell me what he can & cannot do. Do you think the rear carb needs rebuilding our an adjustment to the shaft?
Sorry I couldn't tell you that. I'd trust the mechanic more than me talking about something I don't know from not seeing it. Have you checked the distributor and coil That's the only other thing I could think of to cause that problem.
JR, I notice that your MGC uses a cable to operate the throttle. I have converted my Austin Healey 3000 to cable from a mechanical linkage. I am curious about how the cable is connected to the accelerator pedal in the MGC. Are you able to point me to a parts manual diagram of the mechanism or some photos perhaps taken from your car? Thanks! Lin
Lin, as requested... I am currently uploading a video that will show you the throttle cable mechanism both in the foot well and engine bay. I hope it helps. If you have any further questions feel free to ask. Video will be here once it finishes uploading: th-cam.com/video/gZOHaWhafCM/w-d-xo.html
Good video but for setting carbs you need to separate by undoing clamps and setting individual carbs , then lock shafts again with correct clearance on the forks. lot more fiddling about.
+Shaun Holmes Thanks Shaun, are you talking about the shaft clamps to make sure each moves at the same time? What do you mean by the fork... sorry, you may be talking over my head. I tried to follow the instructions the best I could but skipped some of the "single carb" steps because mine were moving in unison. Perhaps I should not have done so.
Yes , the shaft clamps move inwards to take the pin out of the forks from memory, only need one side off. by setting carbs on there own its stops any influence from other. more often the forks are in sync but if you have stripped them apart best do this part . I feel another 30min video for you. the gap between pin and top of fork has to be xxx inches for both fiddly thing to get right as with everything SU. Well done for your series keep it going.
As @chormy stated…
For setting each carb air flow you need to separate the idle adjustment screws (acting on both carbs) by loosening the two clamps bolts on the butterfly linkage shafts (in between the carbs) and then setting carbs air flow individually with each idle adjustment screw until the carbs are individually balanced with the air flow meter. After balanced then tighten the two shaft bolts locking the butterfly shafts together again (with correct clearance on the forks). Then each carb idle will stop on both idle screws at the same time
Otherwise the two shafts act as one and only the idle screw turned out the most will have any effect on the idle and it will adjust idle of both carbs at the same time. So you just chase your tail.
Any idle adjustment down with this screw will stop when that screw position reaches the other idle screw position
If you adjust the idle after balancing the carbs ensure both idle screws are in same postion so both stop the staft in same position. Ajust the one that changes the idle to desired revs then screw in other idle screw to same position to match that one.
Look up ‘SU Carb balancing’ in plently of other videos or online manuals.
Thanks for the information.
Once again JR this has helped me and given me confidence to tackle the tuning myself . brilliant thank you
Good luck, you can do it.
Haven't had a MGB since the 70's. Great video. Extremely appreciate the attention to detail. Keep up the great work.
Thank you for the comment.
Very good job in explaining, John Twist films are too dark. You can't see what he's doing.
Thanks for the compliment. Also read through the comments below because some very wise people have given tips that I failed to address in the video.
great job! very thorough and explained completely! thank you!
My pleasure.
It's a brilliant video ! Thank you ! This gives me confidence to have a go and tune my carbs !
Thank you. I’m in the process of updating this video but I’m waiting on a part from a supplier so I don’t think I will be able to publish it for several weeks.
@@JRsGarage Hi - Please explain how to set / check the float level please - so much conflicting information - thanks
That’s actually the part I’m waiting on. New upgraded floats.
Extremely useful video thanks, I can safely say your engine bay is a whole lot cleaner than my '68!
My pleasure. Thanks for the compliment.
It’s been said already but a big thanks. Great detailed video. I keep coming back to this again and again. Best SU tune video on the tube 👍
Thank you for the compliment. Happy to help.
What a great video! the explanations, the shots, everything is great, really good job. Keep making content like this... also it really helped me with my Austin mini. Cheers from Chile :D
You are welcome, happy to help.
Helpful - except I think you have to disengage one of the linkages
Correct. I just recently updated this video with a new version. Please see the link in the description of this video to view the new one.
Just. Need those informative MG C CARB TUNE SHEETS!
HS Carb Tuning guide. This is not produced by me but I did add the arrows/colors for clarification.
1drv.ms/b/s!AnVl9mnzz9OrgpVFB-sA4iGHshjP3A
Extraordinary job! Much better to be long and detailed and then allow the viewer to skip parts if he/she wishes, than to do a short video with only highlights. Now if you could just make a similar video for HD carbs. Lots of commonalities though.
Sorry, no HD carbs in my stable. Glad you enjoyed it.
Very very detailed. Thank you for sharing
My pleasure.
thank you for this video, it will most certainly help me set up my hs4's on my triumph spitfire :)
Glad I could help. If you have any questions not covered by the video please ask.
I read it that the 1/16" slack should be in the cable before it moves the cam, not between the cam and the fast idle screw.
Yes, you are right. After reviewing the instructions and the video I think I now have too much free play in the cable/cam before the fast idle screws are engaged. As a result my fast idle is probably set incorrectly. I plan to make a carburetor re-build video this winter and as part of that I will be re-making this tune video. I have come to realize there are several small errors I made or pieces I left out that I should correct.
Thanks for sharing. Well done 👍🏽😎
Nicely done!!
Thanks
Nice explainable video, scope is good tool too, keep up the old work .
Thanks for the comment.
This is the best and most complete HS6 carb adj video for my A-H 3000 MKII BJ7.
A friend of mine recently bought a '68 MGC and is beginning the process of getting it running correctly. I would like to know if the manual you refer to is readily available for purchase online anywhere. I think it would be a great gift :)
Yes it is: MG MGC Workshop Manual: AKD 7133 (Edition 2). a.co/d/e9BR8a2
Great Video - Where /How can I get the SU Instructions you followed - I appreciate the depth and detail you went to in your video - this is what armatures need to do a professional job tuning SUs. Thank You!
It is cobbled together from the pages here, under "general", "single" and "multi".
sucarb.co.uk/technical/
I put it all into one easier-to-follow PDF. If you want a copy, email me: jr.s.garage.mgc@gmail.com
Hi JR, I have a 68' MGC that when accelerating cannot get above 50 Miles per hour or so, the mechanic helping me thinks the rear carburetor needs to be rebuilt; do you agree & if so can I send the carbs to you for rebuild or can you recommend someone in the US? Interested in your thoughts? The mechanic is not comfortable rebuilding my MGC twin horizontal 1 3/4" SU's type HS6 carburetors. Thank you!
I appreciate the confidence but I'm far from a certified mechanic and wouldn't feel comfortable working on someone else's car. I would read through the post here: www.mgexp.com/forum/mga-forum.2/sucarbs-com-review.2488112/
They recommend a business that restores carbs called www.britishsuperior.com/
Thank you for the quick reply JR, am in Tulsa & have limited resources to work on the car's engine, the fellow helping me is great enough to tell me what he can & cannot do. Do you think the rear carb needs rebuilding our an adjustment to the shaft?
Sorry I couldn't tell you that. I'd trust the mechanic more than me talking about something I don't know from not seeing it. Have you checked the distributor and coil That's the only other thing I could think of to cause that problem.
@@JRsGarage Thanks again, I passed along your suggestion!
JR, I notice that your MGC uses a cable to operate the throttle. I have converted my Austin Healey 3000 to cable from a mechanical linkage. I am curious about how the cable is connected to the accelerator pedal in the MGC. Are you able to point me to a parts manual diagram of the mechanism or some photos perhaps taken from your car? Thanks! Lin
Lin, as requested... I am currently uploading a video that will show you the throttle cable mechanism both in the foot well and engine bay. I hope it helps. If you have any further questions feel free to ask. Video will be here once it finishes uploading: th-cam.com/video/gZOHaWhafCM/w-d-xo.html
Good video but for setting carbs you need to separate by undoing clamps and setting individual carbs , then lock shafts again with correct clearance on the forks. lot more fiddling about.
+Shaun Holmes Thanks Shaun, are you talking about the shaft clamps to make sure each moves at the same time? What do you mean by the fork... sorry, you may be talking over my head. I tried to follow the instructions the best I could but skipped some of the "single carb" steps because mine were moving in unison. Perhaps I should not have done so.
Yes , the shaft clamps move inwards to take the pin out of the forks from memory, only need one side off. by setting carbs on there own its stops any influence from other. more often the forks are in sync but if you have stripped them apart best do this part . I feel another 30min video for you. the gap between pin and top of fork has to be xxx inches for both fiddly thing to get right as with everything SU. Well done for your series keep it going.