Under Construction

September 29th, 2008

Please pardon our dust while we improve the website over the next few days.  If you need anything please feel free to call 616-301-2888 or email Mike.  Thank you!

Q & A: MGB Engine Running Hot

Wednesday June 27th, 2007
Q & A, MGA, MGB, MGC, MG T-Type, Midget
Good day, John:

I have a 72 MGB with a rebuilt engine with an alloy standard head (Pierce), 9.0 compression 0.020 oversize pistons and a slightly hotter cam. The distributor has been rebuilt. The engine has about 3000 miles on it since the rebuild. The rebuild went just fine, but I had to rotate the distributor clockwise one tooth in order to have enough advance adjustment on the timing to set it to 16 BTDC at 1600 RPM using a timing light. The engine runs hotter on the gauge than it did before the rebuild especially if the temperature is over 85 degrees, and it has a tendency to run on a bit when I turn off the
engine since the rebuild. It has never quite gotten to HOT, but it now gets very close. Before the rebuild it barely got above the N even on very hot days. I did replace the water pump and the hot water pickup on the head, but nothing else electrical. The radiator has
been recored. The new thermostat is a 185F, plugs are NGK BP6ES and the HIF carbs have free flow air filters with ABD needles. These needles feel a bit lean under hard acceleration (the slight headwind effect). The AAA needles felt a little better, but I was concerned
that they might be too rich. Everything appears to be properly adjusted and timed. The exhaust is a Monza.

Do you have any ideas on why she seems to run hot now? I wonder if the cam is not calibrated properly with the crankshaft and distributor, but I don't know whether this is the cause. I was surprised when I had to rotate the distributor to give it enough advance adjustment to set the timing. I am seeking your advice before I tear into front engine cover to expose the timing chain and
sprockets. I bought a replacement water pump with the cast iron impeller like the car originally came with to see if that would make any difference. The current water pump has the stamped metal impeller. It has not been put on yet, because I want to take care of all the work at one time. I rebuilt the engine and have done it before so I have some experience with engine mechanics. Your advice would be appreciated.
Regards,
Konrad
Konrad!

First of all, I wonder if your engine is truly getting hot. Use an infrared thermometer, pointed at the cylinder head, just below the thermostat. If the gauge is reading "N" the thermometer should be about 185-1... read more