MGB acceleration issue solved by adjusting air fuel mixture screw on SU HIF44 carbs

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My new old '72 MGB still had carb issues. I'm fairly new to MGBs. I watched some vids, and applied what I learned about adjusting the carbs - the results are stunning. It was very rough and no power during off idle acceleration. Was ok at higher RPMs. Now it's like new.
The 2nd part of the vid shows, in detail, how to install the stock air filters and housings.

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14 апр 2022

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Комментарии : 21

@bernhardlist9359 5 месяцев назад

Sir, the pistons have to „klonk down“ yours slowly descend that doesn’t mean the spring is too weak but probably you need to re-center your jets.

@anthonyhfe6450 5 месяцев назад

Thank you for the feedback. It's been awhile since this video was made. The engine is running well nowadays. I don't remember if I did any further adjustment since this video was made. But I know I rebuilt the bottom of the carbs and changed the rubber fuel lines and some other things. They seem to be good now.

@majscrap2629 2 месяца назад

And I thought my exterior was bad! The battery was flipped for a reason. Look up polarity switchover. That is why the tach doesn't work. You need to back everything off and get them to a sound starting point. Don't just go in turning screws. That idle is incredibly high. And the mixture is not off by much.

@anthonyhfe6450 2 месяца назад

Well, I'd rather have a car that's mechanically sound, than one with a pristine paint job. I bought her this way. So mechanical stuff first, paint second. It's always the pretty cars that don't start after a car show - lol. Thank you for the feedback. This is an old video. Carbs have long since been adjusted properly. Have a great summer !!

@johnorchard9164 Год назад

Tap tachometer with back of hand willspring into life works every time. Happy days

@anthonyhfe6450 Год назад

Hey John, thnx for your comment and your advice. Funny, I've seen that "method" on RU-vid. My tach has been rock solid. It just came back without any intervention. I'm hoping it wasn't damaged by a previous owner reversing the battery polarity and grounding the positive. I've changed everything that may have been affected by that. But tach is good for now. My car has other issues now John. The splines are rusted on the axles and possibly in the laced wheels, so that's my next project on the B. You can't have the wheels slipping on the splined axles. Very dangerous. So I have two British cars. One can't stop, and one can't go - lol. The TR7 I blew out a brake line, so I'm changing them out soon, and my B has spline issues. But this is all part of the fun. I have something special with these cars, so I put the time and effort into them so I can enjoy them. Well, take care John !! Nice meeting you on here!

@North49191 4 месяца назад

stick with the factory air cleaners, they don't run well with the aftermarket ones. You also need to disconnect the throttle bar on one side when tuning so that both carbs don't move together. Adjust the idle screw on each carb until around 700 rpm or whatever manual suggests,and the vacuum matches on each carb.Then check lean or rich as you did. Then tighten down the screw on the throttle bar joining the two carbs.

@anthonyhfe6450 4 месяца назад

Hello. Thanks for your feedback. Yes, isolate the carbs from each other. This I understand but it's been a while since I made this video. I'm not sure what I was adjusting here and I think more tweaking was done since. Probably air fuel mixture, in this video. I'll need to watch the vid again. Yes, I still have the stock air cleaners and don't plan on changing them - the same stock ones you see here, except I added the appropriate stickers for more horsepower - lol. Nowadays the car is running well. I need some more road time to truly test her. I will be revisiting the carbs for better tuning when I get back to them.

@anthonyhfe6450 4 месяца назад

The above reply was for North49191. Thanks !

@redbarchetta8782 2 года назад

You're running lean. Jet depth on cold start should be about .040 to .050 down from the bridge, not flat to the bridge. If the carbs are in order and the temperature conspirator which controls the jet height via the enrichment screw is in working order it will lean out to about .035 down give or take. I also find setting them equal and trying to keep the jets as close as possible. It takes a time but these carbs are relatively easy to work on. Once you get the have of it. I installed an AFR gauge on my 74 MGB which has the same carbs. I set it to about 12:7 at idle and that helped a lot. Hope that helps. Go to the MG experience for help as well.

@anthonyhfe6450 2 года назад

Hello Red Barchetta!! Rush fan? Me too. Yes, I think I was running lean. My base settings were even with the bridge plus two full clockwise turns in, as a start. But that was still lean, as when I did the piston test, the RPM dropped. So I had to turn in the enrichment screws on both carbs. Also my idle was high in this vid which I later corrected somewhat. The history on this car (and the condition of these carbs) is a mystery, but things seem to be working as they should. I'm not sure if the bimetallic compensators are fully working. I have the rebuild kits but if they are working properly, no need to rebuild well sorted carburetors. We will see what this summer brings. Yes, I'd like a AFR meter. Some day. But now I am doing the master brake cylinder, as the old one is shot. I may be near your 0.050" parameter just by eyeballing it. Thanks for the help. Much Appreciated! I hope you are enjoying your car, if she is on the road ! 👍

@secretarykilkennychoir7137 10 месяцев назад

Dry piston damper dashpot causes hesitation on acceleration. Top up with engine oil.

@anthonyhfe6450 10 месяцев назад

Thank you for your comment. I'll double check the oil in the dashpots. Lately she's been running well, but it's good to check them.

@grahamepigney8565 8 месяцев назад

Oil in the dashpots is essential before trying to tune the carbs. Check the workshop manual.

@johncooper7242 Год назад

the reason that the slides are not going fully down is because the idle speed is way too high !....the engine is creating a large vacuum which is lifting the slides slightly as they are intended to do. You cannot tune the idle mixture with the engine speed that high . If you lower the idle speed to around 800-900rpm then the slides will come down and you will be able to tune the mixture

@anthonyhfe6450 Год назад

Thank you John. Yes, rpm too high. Yes, this was true then. I think I have them almost good now, adjusted around 1000 rpm, but something weird is happening. When I use the Uni-Syn carburetor synchronizer, it seems to cause the engine to almost stall when I use it on the rear carb, but doesn't seem to do this on the front carb. So I'm not sure on that. Thank you for your help!!

@johncooper7242 Год назад

@@anthonyhfe6450 sorry didn't see this until now. It sounds like one of your carbs is running too lean and the other too rich. What happens when you lift each slide about 2- 3mm with a small screwdriver ? The engine should very slightly increase rpm and then go back to the same idle speed. If the engine dies the mixture is too lean and if the engine increases sharply its too rich . You might need screw the mixture screw clockwise to go out as much as 3 turns to get the mixture right

@anthonyhfe6450 Год назад

@@johncooper7242 hello John Cooper. Thank you for your assistance. It certainly could be that one is lean and one is rich. I'll be revisiting this soon. Yes, lifting the piston u should get slight increase in rpm then back to normal - absolutely. Thnx again. Hope you are doing well.

@user-do5hd7zb4x 9 месяцев назад

Dear Sir it may be possible to extend the life of your two air filters by stretching clean new panty hose over the exterior of air cleaner elements. This in effect will prevent bugs moths dirt from prematurely clogging your air filter elements. My dad had a volvo and used this trick and as far as I know it worked. It may affect rpm of engine but I thought I would share this with you. Hope it works for you whatever you decide. Happy tinkering!

@anthonyhfe6450 9 месяцев назад

That is an interesting idea. And I'm sure it's effective. Thnx