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MG MGB Technical - Hard Cold Weather Starting

My 3-main MGB engine is very hard to start now that the cold weather has arrived. During the summer and last winter, starting was not a problem. The car runs great once started. Here are some parameters:

1. pertronix coil and distributor (Nearly new)
2. Carbs rebuilt and properly adjusted. Choke seems to also be adjusted properly (???)and is used during starting. Spark plug color is perfect.
3. Timing is advanced just short of pinging.
4. Battery good.
5. All LT and HT ignition wires are nearly new.
6. NGK BP6ES spark plugs have less that 5000 miles and are gaped at .030"
7. Engine recently rebuilt with compression at approx. 160 PSI.
8. Starter motor nearly new and has good connections to ground, starter switch and battery.

All suggestions/comments will be appreciated.

Frank Grimaldi
Frank Grimaldi

I'd start with the choke settings. My daily driver was a 70 MGB for many years back in the 70s and early 80s. It was a 5 main bearing high compression engine, completely stock, but should be quite similar to yours. Many mornings were below zero here in Missouri and the car sat outside. I would pull open the choke as far as possible, turn it to lock, never touch the accelerator, wait until the SU fuel pump quit clicking and was pressurized and turn the key. It would start within a fraction of a second. I had to monitor the choke for a few seconds until the motor settled out, but it started 99 times out of 100. If it didn't start and cranked even a second too long, I was screwed, it wasn't going to start. Some mornings were so cold, it barely wanted to turn over, but almost always started. I don't remember any secret to the choke settings, but sure they were precisely what Haynes and other manuals prescribe.
Rick Penland

Frank,

In addition to what Rick said about the choke being adjusted properly, if it is cranking slowly, you could consider using synthetic oil in the cold weather. When my GT was tough to start the other day, I found that the choke was not moving all the way.

I don't know what the opinions would be about synthetic with respect to the ZDDP issue. But, I put synthetic in my Benz diesel the other day to get it cranking faster, and it certainly helps. Temps have been in the single digits F here the last few days.

Charley
C R Huff

I'd also be suspicious of the choke setting. I ran my '67 for 12 years with the stock SU HS4s and it always started right up even when left sitting for 6 months. This was in NJ Winters that got down to the teens almost every night and the car had to sit out in the cold driveway. Be certain that your batteries are up to the task as older ones can't perform properly when it gets cold out. RAY
rjm RAY

Frank,
I know it's heresy, but I got tired of very slow cranking in cold weather...even with a brand new Bosch battery...I replaced the starter with a hi-torque starter...half the weight and 3 times the cranking power...a BIG difference...not for everyone I know but FWIW...
Bob Dougherty

Frank I'm in agreement with Bob on this issue,I replaced the starter on my '73BGT, After having exactly the same problems as you in the winter months.the old starter 33yrs old, was tired. Wish I had replaced it a couple of years earlier. Be like me ask "Santa" to bring it for you. Regards Bill
wm griffiths

Just what is the starting problem? Not turning over at all? Turning over but very slowly? Or turning over normally and just not catching? Causes for each of these are very different.
PaulH Solihull

MGBs like your 3 main model are vintage cars from the 60s and, like almost every car from that era, have their own "personality" regarding cold weather starting. I believe the secret is getting the engine to "catch", to use a colloquial term from that time. Indeed, a good battery and starter are essential, but just a couple of "stiff", cold engine revolutions will start a B engine if it has spark and the proper fuel mixture. If the fuel mixture won't ignite, you'll flood the engine quickly and you can crank until you melt the starter to no avail. Make sure your choke cable moves freely and that you are getting the full range of movement. Make sure your idle raises and returns. The electric fuel pump should get fuel to the carbs and proper idle linkage adjustment should set your throttle. Don't pump the accelerator or otherwise engage it. At least that has been my experience. Check the choke linkage. Check your choke cable clamps by manually lifting the choke cable at the engine to be sure the choke linkage moves completley to its stop point and the cable clamps aren't worn and "sloppy" requiring some of your cable travel to just take up the slack. I noted your carbs are rebuilt, but what about the linkage? What temperature are you referring to when having the problems?
Rick Penland

I agree, these cars have their own personality and needs. My 73 roadster needs full choke while cranking, catches within a few revs, then the choke pushed immediately half way back. The V8 needs full choke for starting *and* for the first few moments of running, then both are gradually pushed back from their respective positions as the engine warms. In my experience if they don't start for any reason then cranking on full choke *will* flood them as Rick says, but you can smell it, particularly in a garage. If that happens crank with the choke pushed fully back and the throttle wide open, which will clear the flood and allow it to start *if* it isn't a case of no spark. Be ready to release the throttle and half-pull the choke if it *does* catch.

Check the choke movement, on HSs and HIFs the cable pulls on a lever on the choke spindle. This should be set such that the lever is at right-angles to the cable when the choke is half pulled. If the lever is more advanced than that then it can end up in line with the cable and hence not capable of being pulled any more, even though the enrichment on the carbs is only part way. Conversely if the lever is too far the other way it can make the choke very stiff to start moving.
PaulH Solihull

I would consider the high torque starter motor, but I have a question...

My car is an MGTD with a 3-main MGB engine installed and is fitted with the standard starter motor. I can install the starter from under the car. The clearance between the engine and frame rail is just sufficient to accommodate the diameter of the standard starter motor. My question is: Is the diameter of the high torque motor equal to or less than that of the standard starter? Can I expect installation problems?

Thank you,

Frank Grimaldi
Frank Grimaldi

If you still have gas in the tank from this summer, then fill up the tank with fresh gas and try again.

The gas sold in the winter is more volatile than that sold in the summer. Makes for better starting. Old gas is also less volatile.

If you do have 'old' gas in the tank, then get a can of 'new' gas and slightly wet part of the air filter and try starting it.
werner haussmann

Do you mean hi torque or geared? They are two separate animals, the former being much the same size and arrangement as the originals from what I have seen - http://tinyurl.com/2alf2xl, which may or may not give more torque than normal. The latter are usually smaller and lighter, like http://tinyurl.com/34lpfv4, which is also entitled 'hi torque' but which is stated as geared in the description. These are arranged completely differently with the solenoid in line with the pinion, and the motor attached to the side. The motor is actually smaller than the solenoid on these.

Can't speak for change of formulation winter and summer in the UK but I have never had a problem with 'old' gas, it can be six months old by the time I need to refill the tank in spring.
PaulH Solihull

This thread was discussed between 15/12/2010 and 21/12/2010

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