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MG MGA - These cars are weird...

This is probably tied to my post below. OK two events yesterday.

Drove to work (32 miles). Temp about 78 degrees. Drove streets and highways without stopping in traffic. Highway speeds up to 68 mph. engine temp ranged from 185 to 190. Car ran perfectly and more notably idled perfectly after the long run to work.

Drove home same route. Temp about 86 degrees. First half of the trip was stop and go traffic, last half of the trip was clear highway running at 68 mph. Engine temp ranged from 185 to maybe 195. Obviously the engine bay overall temp was likely much higher during the stop and go.

So here's the thing. During the stop and go traffic the engine idle quality started to degrade.OK I get that, however after I had driven at highway speeds which should have cooled the engine bay down the idle was still crap.

So something that affects idle is getting hot and once its gotten hot won't stop affecting idle until it completely cools by sitting still for an hour.

What could that thing be? and why is doing that?
T McCarthy

At the higher temp on the drive home it may have been just enough increase in under hood temp, carb temp, and even the fuel temp to result in fuel bubbling out of the jets at idle. Not enough to notice at speed. You may want to try lowering the fuel level in the float bowls slightly to reduce or eliminate the problem.
John H

A related question to float level adjustment. When I adjust mine to spec I can see fuel just below the top of the jet. Is this correct? I ask because my adjusting nut is screwed right up to the stop to lean the carb out.
Thanks
Morris
M. E. WADDS

Could be the condenser going bad.
David Breneman

I WILL AGREE DAVID BRENEMAN IT HAPPEN TO ME NOT TO LONG AGOO IT IS INEXPENSIVE CAN GET IT AT AUTOZONE FOR AROUND $3.00,BE CAREFULL WHEN REPLACING THAT LITTLE SCREW IS A CURSE,BEST THING TAKE DESTIBUTER OUT ON BENCH FOR WORK TO PREVENT LOTS OF TROUBLE,IT IS EASIER TO TUNE IT THAN LOOSE OR DROP THE SCREW INSIDE THE DESTIBUTER. ANOTHER THING TO CONSIDER IS THE GAS FLOW, A GAS PRESSURE REGULATER COULD BE HELPFULL LOOK UP YOUR SPEC. IT IS 3 TO 4 I SET MINE AT 3.5 I HOPE THAT THIS MIGHT SOLVE YOUR PROBLEM.
GERRY DIEPERING

Thanks all.

Here's a little closure on the issue.

It appears to be a combination of the mixture running a little rich and the float bowl fork setting, which I sent a little higher than 7/16ths.

The condenser is a good call but this an electronic ignition.

Thanks again
T McCarthy

I'm convinced we all now have a problem with fuel volatility as the boiling point is much lower now than when we had leaded fuels.

That said I find once my 1600 gets a bit hotter than normal, it seems to take a long time to cool down again once running normally in top gear. You mention running at 68 mph in an 86 deg ambient temp. If it gets that hot here I find I have to run at around 40-50 mph to keep things happy. The temperature always rising once steadily running over 60.

The quickest way of cooling a hot MGA is a nice long downhill section on overrun. Using a 'summer' stat helps delay a temperature rise of course and I'm finding an electric fan (+ engine fan) a must in hot traffic jams.

Without the electric fan I've had a water temp reading of 100psi on the oil gauge!!!

Pete
Pete Tipping

This thread was discussed between 29/06/2007 and 03/07/2007

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