1972 mgbgt

Author
Discussion

reghog

Original Poster:

7 posts

114 months

Friday 26th September 2014
quotequote all
I have owned a 72 mgb for about 2 yrs now. Its used most days in summertime and runs well apart from the idle drops if i get stuck in traffic, and will stall eventually.Looking at discussions on this I have seen breather issues and fuel starvation. Ive also realised that i have no charcoal filter...Is this correct on a 72 ? And should the fuel cap be vented . Any thoughts?

Expatloon

215 posts

156 months

Friday 26th September 2014
quotequote all
Charcoal filters were never fitted to UK cars, none of that US emissions crap ever was thank God !

Your fuel cap should be vented but that won't be the cause of your problem nor will it be fuel starvation, that would show up when running when the fuel demand is much higher.

My guess is that your carb heat shield is past it's best and has lost it's asbestos pads.

nta16

7,898 posts

233 months

Friday 26th September 2014
quotequote all
as put check your heat shield

this is the plastic vented and filtered oil filler cap you want, £4 from MGOC Spares, rather than bling chrome ones




as you've had the car 2 years you should be on your first (if not second) change of brake fluid, coolant and gearbox oil

have a look in your Driver's Handbook for details if you've not got one then buy one and read it then you'll know more about the car than many long term owners - (Ref: 0052) - http://www.mgocshop.co.uk/catalog/Online_Catalogue...

my Midget one as an example of contents -

reghog

Original Poster:

7 posts

114 months

Saturday 27th September 2014
quotequote all
Thanks for this, the car is regularly checked and lubed as necessary, though i didnt realise the brake fluid was such a regular change. Re the heatsheild, looks pretty good with aspestose all there.I may just try loosening the filler next time she starts to drop idle, though shame if i have to change my nice chrome cap for this piece of black plastic. Was that the original ? If its not the filler or the heatshield any other ideas. Timming and carbs seem to be nicely set up and plugs nice dry brown colour. compression eaquel on all cylinders at 150.

reghog

Original Poster:

7 posts

114 months

Saturday 27th September 2014
quotequote all
Hi again, just realised this pic is the oil filler ( as you said )I was more concerned about the fuel cap and venting. Apologies for bad spelling previously, too used to auto spell checker.

nta16

7,898 posts

233 months

Saturday 27th September 2014
quotequote all
if your petrol cap isn't venting then it's easy to check just by removing it and seeing if the car idles better

take a (good quality) photo of your carb heat shield and surrounding area and put it up here for others to see

order of priority on car
. BRAKES (fluid, flexi-hoses, pads, discs, shoes and drums)
. tyres - if they're old and/or little used then they can go hard on and regardless of how much tread depth is left on them

tyres effect your braking, steering, suspension and ride quality and noise
. suspension - dampers, springs and often forgotten bushes
. lighting and windows - see and be seen

there are loads of things that could be causing your current problem so you need to conduct a step by step diagnosis

you notice the engine and carbs are not priority items but will be covered in full and proper regular servicing

reghog

Original Poster:

7 posts

114 months

Sunday 28th September 2014
quotequote all
I did have the car thoroughly checked when I bought it and parts replaced and upgraded accordingly. But ( and Im no mechanic )Im doing my best to learn and keep on top of any problems. As I use the car regularly the idle drop is a pain. I'll try loosening the filler later and see what happens. Pics of carb area attached though its difficult to get a good shot of the heatshield.
thanks Andy[url]

nta16

7,898 posts

233 months

Sunday 28th September 2014
quotequote all
wow, they look like original 1970s quality photos

others would know better than me as I've not owned a BGT for 20 odd years - is that heatsheild with added asbestos pads original or home made?

I too am no mechanic and do as little as possible on the car if I can afford to pay others but the very simple stuff I do myself including of course the driver's checks

if you read and refer to a relevant copy of the Driver's Handbook it will tell you all you need to know about driver checks and simple servicing

as I put before this problem could be for many different reasons - if you use the car regularly is this only on short journeys, if so and the car is in a good mechanical state and has been serviced and set up properly then 'Itailan tune-up' might help a little (take the car on a good blow out run where you are using higher revs and sustaining higher speeds for many miles)

if you already use the car regularly for reasonable length journeys then you need to look elsewhere

to get you over the problem for the time being (and this is not the solution if the car has already been serviced and set up correctly) just slightly increase the tickover equally on both carbs (see Driver's Handbook) this should at least prevent the risk of stalling at inconvenient places

ETA: when was the last time your paper air filters were changed (or perhaps cleaned)

Edited by nta16 on Sunday 28th September 14:24

reghog

Original Poster:

7 posts

114 months

Sunday 28th September 2014
quotequote all
ok so I have taken the the car out today and left her running to really warm up. As expected shortly after the electric fan cut in, the revs dropped from 9000 to 5000 and a bit lumpy. Opened fuel cap and no change. Then opened oil filler and the revs recovered fairly quickly. I tried this a couple of times to be sure. So looks like I need a new filler cap. I wonder if it will be that easy !
I beieve the heat shield is all original and the air filters have been changed about a year ago. I have also ordered a drivers handbook for a little bedtime reading. Thanks for the advise and help
Andy

nta16

7,898 posts

233 months

Sunday 28th September 2014
quotequote all
have a look for the John Twist video on checking the engine breathing on a B, the pipes and engine chest covers and chest cover gaskets, not blocked or not sealed (sorry I can't remember the number of the vid)

as soon as you get the relevant Driver's Handbook and actually thoroughly read it you'll see why I always suggest getting a copy of the book even before going to look at cars to buy as by reading it you'll know more than most long term owners

and you'll also see that some of the 'pub/internet wisdom' is bks and many answers given wrong

I've got a list of the few updates you might need for the Driver's Handbook coming from over 40 years ago if you want them

when you get the Driver's Handbook check out the full 36k-mile service schedule and see if you've not checked or attended to any of the items yet as I recommend a new owner asap after collecting the car carry out a staggered 36k-mile service/check up inbetween regularly driving the car on reasonable distance journeys to get full used to the car and get to the niggles to iron them out sooner so that you can learn just what your car should be cable of sooner rather than driving a car that average - because the average is very low indeed

if the new black plastic vented and filtered oil filler cap doesn't solve the problem you've only lost about £4 and have a new part that isn't p*ss poorly made like some and could last you decades

nta16

7,898 posts

233 months

Sunday 28th September 2014
quotequote all
ETA:
when you read the relevant Driver's Handbook you'll wish you got a copy when you first got the car if not before

if I'm wrong about this please don't be frighten to say so - if I'm right suggest the same to other MG/Triumph/Rover/etc. owners