MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - runnig hotter after change of alternator

Hi all,

My 70 bgt, hs4 carbs with standard needle but K&N filter (I checked the mixture with Colortune), the cylinder head skimmed to give about 9.5:1 CR. Otherwise all standard.

Here the ambient temp is about 90F in summer time, the b used to running at 195F with electric cooling fan on after some hill climbing.

Last week I replaced the alternator with a new one as the old one had been retired. After that, the engine ran hotter (temp at idling is the same), the engine temp is 205F instead of 195F with the same route.

The mechanic explaned to me that might be the ignition coil's primary voltage in the past was low as the old alternator's output was low and made the ignition no good. After changing the alternator, higher voltage output made the burning better which highlighted the standard carb needle was too lean at high rev with K&N. He advised me to change to a richer needle. His explanation seems reasonable!

Should I order the richer needles? Any idea?

Thanks in advance
Ennio
Ennio Wong

Check your fan belt. If it is loose, it will not drive the water pump as well as it should, and that could cause overheating.
Bob Muenchausen

I find that the temp. gauge reading, even
with a good instrument voltage regulator,
fluctuates with load, e.g. headlights on or
off. Maybe the new alternator is providing
a higher voltage and hence the gauge is
reading a bit higher? Have you cross-checked
the temp. gauge with a thermometer in the
radiator opening?
Ronald

Bob,

My b has 2 belts system, a long belt without idler pulley driven the main pulley, water pump & a/c compressor which has 2 grooves (a/c compressor is adapted from Rover Mini Cooper). Then a short belt driven the alternator by a/c comp. I didn't touch the long belt during the change of the alternator, so I hadn't thought about it. I would check it.

Ron,

I would check the temp with a thermometer.

Thanks for your input

Ennio
Ennio Wong

This thread was discussed between 28/09/2003 and 29/09/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.