If you have to replace the bushings in the throttle spindle, this link may help you:

https://mgbgtle.blogspot.com/2017/05/rebushing-hif4.html

Update, I have to replace the throttle spindle, but is there a way to remove the bush in case I do?

Thai168:

Because it is s different problem, you should start a new thread on this oil problem.

Yes, their was a sign isn't smoothly road test, not much. I'll test this and get back. I been trying to fine out where oil was leaking from even after cleaning the gear box. I don't see oil from the missing bolt but a little from crack, I just don't see how oil is on the nut. Should I replace the cover?, if so I'll order the throttle shaft kit if the test fail. Thank you very much

What Bluedragon says about air leaks is correct. Significant leakage could likely show up as dirty, sooty plugs - if you have undetected leaks and you tune the mixture at idle, you will be compensating for the extra air with additional fuel. So, when your engine is running at half to full throttle, it would end up running rich because the vacuum on the leaks will be very low.

A common source of leakage on a SU carburetor is the throttle shaft. The bushings and shaft can wear, leaking air there. 

You may be able to detect the leakage by spraying carburetor cleaner around the shaft bushing and listening for a change in idle sound and RPM. Or pack the bushing with grease and see if this makes the idle and airflow more stable.

One sign of the carburetors being too lean is if the car surges while you are cruising at a steady highway speed. Often the car will not accelerate smoothly if too lean, it may stumble and even backfire.

Your spark plugs look just about perfect to me. Time will tell - if it is too lean, you may see some burning away  of the electrodes, though it would be small and hard to detect. Using a hose to listen is the "old-school" method - before somebody invented uni-syn type devices. If both carbs had vacuum ports at the throttle plate (probably not) you might be able to attach two vacuum gauges to compare.

I center the jet and it solve the issue of overrun and run much better but I can't synch. with the uni-syn tool so I used a hose to listen if the same amount of air, and mixture without the vacuum contact. That not the correct way to tune but I took it for a drive and check the plugs. Can you guys see if is too lean? Where else can air leak to make it for not to synch.

You should be able to centre the jet with the carb still on the engine. You may need short wrenches to do it if the fittings are stiff. But you may be able to do it with your fingers if you loosen the lock nut enough

Since you have twin carbs, your intake manifold is separate from your exhaust manifold, which mad removal of the twin-carb setup easier. The intake manifold has two branches that bolt to the head with two studs and nuts each. The 4 nuts also hold the exhaust manifold to the head, so when you removed the intake manifold, the exhaust flanges were no longer held tight. But if you did not undo the two nuts at the outer ends of the exhaust manifold, the exhaust manifold and the manifold-to-head gasket would not have moved. So when you bolt it back together, the exhaust manifold should not leak.

When you bolted the intake manifold back on, it should go back where it was before you started. You can look for the impression on the gasket. Some manifolds have alignment rings that fit into the head intake ports to align them perfectly. Most do not. If you have them, great.  If not, alignment is not so much a problem. If the ports of your head and intake have been machined to align perfectly, it would be necessary to get the alignment as close as you can. Most engines are not that carefully done, so the ports probably don't line up perfectly anyway. So, if you can see the imprint of the intake manifold flanges on the manifold gasket, that should be close enough.

To install the intake, you should get it all lined up and tighten the nuts finger-tight. Then slacken the two end nuts the same amount and re-tighten all the nuts gradually and equally to get even pressure on the gasket for each intake flange and exhaust flange.

The notches and holes in all the manifold flanges are usually just big enough to fit over the studs, so you can't be too far off. Be sure to install the washers the right way - sometimes the intake flanges are thicker than the exhaust flanges and need stepped washers to make up the difference so the nut applies equal pressure.

Possible leaks:
If you smell smoke or exhaust fumes, the exhaust manifold is not tight, Don't over-tighten the nuts or you will have worse problems. You may eventually need to remove the manifold gasket and put a new one on.

If the intake flanges are not tight, you should not smell raw fuel - when the engine is off, no fuel is flowing and when it is running it will be sucking air in through any leaks, so you won't get fumes anyway. What you will experience is poor tuning because of the air leak. There are ways of finding where an air leak may be, but that is another subject.

Hi, thank you for the info. I just watch a video on replaceing new jet and remember not centering the jet, I can't believe not. i replaced it when the line broke off . Will I need to them off again to center the right jet or can i adjust with them on? I saw a video on youtube from HRE, he was installing the engine when he mention the manifold might slip. I would smell something like fuel or smoke I don't know how to describe it, so I check manifold to see if it move not adjust, sorry. Do you think I may have bent the needle? Thank you very much you guys, weather very hot. I'll update

Hi Thai, I think you are so far out in left field that you need to start over with some basics before you worry about any fine tuning.

You say you changed the right jet.  Why??  Did you remove the carb from the car to do this??  There is a tiny rubber seal/washer that goes on the end of the jet tube where it attaches to the float bowl.  Its is very easy for this seal to slip out of place as you attach that end of the jet.  This can block the fuel flow to the jet itself either partially or fully.... especially if the carb was still attached to the manifold/car..  When you installed the new jet, did you centre the needle?  Did you need to?  (it might be a sprung needle .... ) 

Language could be an issue but I'm sure we can work through that.  You say you "adjusted the manifold..."  But the manifold is a solid lump of alloy ...it doesn't have any adjustments ... so what did you actually do?

Did you pull both carbs to pieces while you were changing the right jet?  if not, you should put the right piston back in the right carb and look for another reason why the piston doesn't fall freely.  (See if it falls freely with the needle removed.)   If its sticking clean the inside of the bell and the edge and the shaft of the piton with a soft cloth dipped in fuel - DON'T use steel wool or any other abrasive (sandpaper or stuff with grit in it).

When the carb piston drops cleanly with the needle installed and centered then reassemble it on the manifold and set up the linkages so that both carbs operate together.  Then you can think about getting the tune right.  There's no way you can get the tune right if the carbs not operating properly.

Cheers, Ian

Look up how to centre a jet around the needle. It has to be absolutely centred on the needle or it will rub and stick. There are two parts that hold the jet in position - each one is designed very slightly off-centre so that by rotating each one, its bore centre moves in a small circle. The combination of rotating the two circles eventually ends up with the centre of the jet in line with the needle. This is for carbs with fixed jets held rigidly in place. Later carbs use a spring-loaded needle which allows it to shift slightly to self-centre on the jet - nice but eventually (many years), the needle rubbing in the jet can wear the jet hole slightly oval.

Thank for the respond, I did a pistons test and found that it wasn't drop equally, so I did the switch but befor I did check the piston, and the right one has resistant but after the swith, now the left has it but both respond to the piston test, still can't sych without the engine being stall. I change the right jet not long ago. I'll try to make a video and post here or youtube. Thank again

I am no expert on twin carbs, but I see a few of possibilities to check.

1. Are you sure the right carb is getting fuel? Remove the fuel bowl lid and check for fuel. Check also that the tube to the jet is not plugged.

2. Make sure the throttle of the right carb is connected with the other carb and the accelerator cable.

3. You say the piston in the right one does not respond. Remove the damper (the plunger under the black cap), remove the air cleaner and see if the piston moves freely all the way up by lifting it with your finger. The little test rod only moves it a little bit. If it doesn't move freely, check that the jet needle is not bent or loose and the jet is properly centred. When trying to adjust idle mixture, you may have shifted the jet so it is not centred on the needle.

4. Have you had the dashpots removed from the carbs? Each dashpot should be matched to its carb and maybe they got switched?

5. You said the ignition has been changed to a vacuum type. It should only be disconnected when setting the timing. When you do have it disconnected, the port on the carb must be plugged during the work of setting the timing. If not, you would have an air leak, but not enough to stop a carb from working. Check also that the vacuum line is connected to the right port.

I'm not good describng, I hope someone understand.

I replaced the float and adjust the manifold. I adjust back to the baseline and idle fine, but when I check the fuel mixture, the left piston respond but the right one just, nothing. I try to sych. the left one shut the engine off, and the right very little effect, this happen befor so I took it for a drive, and a very good one but when I turn the engine off I get overrun. Did I missed something? I had the electrical work on by a Mini specialist and one of the change was the distributor with a vacuum, I removed it when I try to tune it.

I hope guys know whats I'm saying, Thank for taking the time