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MG MGA - No Choke Needed - Confused

All

You may have seen from a recent thread (distributor again) that I am now up and running with my newly installed electronic ignition.

What surprised me this morning is that the car did not like any choke when starting from cold (15 degrees outside temperature). It ran great immediately with no choke. After my run I had a look at the plugs - all lightish grey and no soot.

I checked out and very accurately adjusted the carbs a couple of weeks ago and everything was ticketyboo. I also recently replaced cork seals. Everything adjusted and moving correctly.

Am I worrying about nothing?

Steve
Steve Gyles

This sounds terminal, you ought to sell your car immediately and by something reliable



Regards

Terry
Terry Drinkwater

Hi Steve! Don't look a gift horse in the mouth! It may well be that the electronic ignition is simply much more efficient than the old points and condensor system, and provides so much better ignition that a rich mixture is simply not required for starting! If the plug colour is good, and there are no signs of detonation, then I think all is good, and that you should enjoy the petrol savings that come from not having to strangle your engine! Cheers, Glenn
Glenn

if you are selling, I insist on a discount for the bent bumper...
dominic clancy

Dominic: If steve is selling, I insist on a discount because the choke is not required to start the vehicle. This totally undermines the vehicle's authenticity and mistique, and ruins the driver's ability to brag about the car's complexity of operation. Cheers, Glenn
Glenn

Thanks Guys. Not for sale! Now for the differential front end leak.

Steve
Steve Gyles

Make sure the jet tubes are returning to their full up position. With new seals it may be a touch stiff and the springs may not be pulling them all the way up. If that is the case you may be too rich while running. Doesn't sound like something to ignore.
As for the differential pinion seal it is pretty simple to replace. First unbolt the 4 bolts that hold the drive shaft to the flange. There should be enough room to move the driveshaft up to gain clearance to get to the big nut that holds the flange to the diff. The nut will be very tight, over 100 ft lbs, you will need to set the brake or if it slips have someone hold the brake pedal down to remove it. After the nut is off the flange should slide off without difficulty. Pry out the old seal and carefully install the new one. Some diffs use a crush sleeve to set up the diff and the position of the nut is critical. On a MGA this is not the case. The flange nut is just set to the proper torque. Reattach driveshaft and enjoy.
R J Brown

Thanks RJ

The tubes are returning fully up. I have gone to a lot of trouble setting up the carbs this time as poor fuel consumption had been an issue with me. Perhaps I have finally got it right and, with the electronic ignition now working right, am surprised how little choke I need. I track my fuel consumption very closely and will know in the next 200 miles if my efforts have been worthwhile.

I have already made up a steadying arm for undoing the nut. The book says 150ft/lbs. I hope my pneumatic wrench is up to the job. It specs 250ft/lb, but my smallish compressor may be the limiting factor.

http://freespace.virgin.net/stephen.gyles/odds_and_sods.htm

Probably do it this weekend.

Steve
Steve Gyles

Hi Steve

Glad you're keeping the car. Have you opened up the plugs gaps? You can probably get away with 32 thou, a fatter spark burns fuel more efficiently. What coil are you using? Sorry about the spelling misteak, I meant 'buy' not 'by'. I'm not stupid, I just look stupid

Regard

Terry
Terry Drinkwater

Steve

Be VERY careful using the pneumatic impact wrench. A small compressor will merely temporarily limit the available torque as the available flow rate/pressure is reduced. Take you finger off the "trigger" and the compressor will bring the pressure back up and you can get the full 250 ft-lb. I would suggest that using a manual torque wrench is probably a better bet on this.

FWIW

Larry
58A
Larry Hallanger

Terry

I had them at 30 thou. Just been into the garage and opened them up to 32. Let's see what happens.

Re the coil, I know you previously said to fit a Lucas Sports Coil. When I last spoke with Aldon they said an ordinary coil is ok. In fact I think they said too powerful a coil could damage the electronic ignition. I have an ordinary Intermotor coil. Happy to listen to more advice on this topic.

What's a U between friends? I knew what yo meant.

Steve
Steve Gyles

Larry

Thanks for the warning. Not having a pit nor a lift I have been contemplating how to lie under the car and get a 150 lb pull on my torque wrench, then I remembered my pneumatic wrench! My back is not good, so this type of job tests my physical capabilities. But I'll have a go before resorting to a professional garage - sorry Terry and all.

Steve
Steve Gyles

Steve, the impact gun should remove the nut with no problems. When retightening, place your torque wrench on the nut at a slight down angle that will allow you to put a jack under the wrench handle. Jack up the handle until you get your 150 ft lbs. You may have to reposition the wrench and repete to get to 150.
I had to do this on a chevy truck to get enough torque to start crushing the crushable spacer.
John H

To tighten the nut you can put a torque wrench and socket on the nut and rest the handle of the torque wrench on the leaf spring and just push the car till it clicks.
R J Brown

Thanks guys. Good tip.

Steve
Steve Gyles

I have a similar problem with my Magnette (no choke required to start). In fact the choke kills the engine. The plugs are a good colour. The only problem is that the idle is too fast when warmed up.
Dan Smithers

The choke should control both the jet position and the throttle plate position. The movement of both, when the choke is used, is supposed to be progressive as the engine warms up.

With full choke, both the jet and the throttle plate move to their extreme positions (for the choke control ~ the jet drops quite a bit and the throttle is cracked open a bit more than at idle. This positioning allows more gas and a somewhat faster idle speed than at full operating temp.

As you work the choke in during warmup, the jet should return to its final position sometime before the throttle is allowed to return to its normal idle position.

Given the situation you have, it is hard to judge if the linkages for the choke system are working as intended, or not. If the plugs look OK under normal operation, I would guess that you have something like the right needle and jet, but for it to start right up from cold without using the choke is not the usual situation most owners have experienced, and I don't think it would hurt to check to see if your choke linkages are working/setup as they should be. Apparently your jets are not stuck in the down position by friction, so it will be interesting to find out if you find something amiss with the choke linkage/positioning system. Or, you may just be lucky?

You might want to check out Barney Gaylord's website to see if he has some comments on proper carb/choke linkage setup and operation ~ http://mgaguru.com/mg01.htm
Bob Muenchausen

This thread was discussed between 27/09/2006 and 06/10/2006

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