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MG MGB Technical - Overheating and timing

Last year I had the head of my 64 rebuilt and modified; larger intake valves, 3 angle grind, porting and all that stuff. It ran well at high RPM but had no torque. I went and got an adjustable timing gear and retarded it 2 degrees. The rest of my engine had over 100K miles and couldn't take it. When rebuilding occurred it was bored 30, line honed, center honed and balanced. All else was the same as the previous engine. When putting the engine together I had this vision about retarding the engine am little more to get some more low end as I live in the hills, and then I thought that I could advance the distributer to fine tune it. I now have a car that runs real well but the temp runs in the 220 degree range when I am making power ie: going in excess of posted speed limits, going up hills fast etc. Anyone have any ideas where I went wrong/ Thanks for your consideration. Ed Kulick
E kulick

Ed-
Until you've made sure that the cooling system is in place it's hard to tell if the problem lies with the engine. All too often an old cooling system will be sufficient for a stock engine but is completely inadequate in when asked to meed the needs of a higher performance engine. The early three main bearing B Series engines had cooling passages between all of the
cylinders, but the cooling passages between cylinders 1 & 2 and 3 & 4 were deleted when the engine was redesigned into its five main bearing version. Never use plain water as a coolant in the cooling system. It will rust the cooling passages inside the engine. Rust will act as an insulator, trapping heat inside the engine. Instead, use a mixture of antifreeze and distilled water. Descale and flush all of the components of the entire system, including the engine, radiator, and heater core, to remove the 39 years accumulation of muck, rust, and mineral deposits which act as insulators that keep heat from being dispelled by the cooling system. You'll be surprised at how much cooler the engine will run in the summer and how much warmer the heater is in the winter. Install a coolant pump with the earlier cast iron body as it has the more efficient die cast impeller which has less of a tendency to cavitate at high RPM. Make sure that the system is refilled with a mixture of a good ten-year antifreeze and distilled water. Why distilled water? Because it won't coat the interior of your system with mineral scale. Why the more expensive ten-year antifreeze? Because it has special additives that will extend the life of your water pump and because you don't really want to do all this all over again next year, do you? Be advised that at highway speed it is primarily air pressure that forces air through the radiator and not the fan. Air pressure tends to take the path of least resistance, moving through any and all open spaces in and around the radiator mounting diaphragm rather than through the radiator. Therefore, if you want the cooling system to function to maximum effect, be sure that all of the spaces around and above it are well sealed. Use a 165 degree thermostat for summer use or a 195 degree thermostat for winter use and install a seven-bladed cooling fan for more effective low speed cooling. It?s a simple matter of removing the fan pulley from the coolant pump and using it as a jig to drill four holes through the boss of the plastic fan that will align with those of the fan pulley. Due to its higher aerodynamic efficiency, this fan draws more air through the radiator rather than just stirring it around inside the engine compartment like the older paddle-bladed metal fans, requires less power to perform its function, and is actually quieter. Because it is lighter, it has less inertia and thus puts less strain on the pulley belt whenever a change in engine speed occurs, thus prolonging belt life. To install this fan on a MKI model it will necessary to either mount the short-nosed coolant pump of the later 18V engines or install the radiator of the 1972-1975 MKII models along with the complimentary thermostat housing. In a few rare cases the distance between the fan and the radiator will be insufficient to permit the mounting of this more efficient fan and the shorter pulleys of the 1972-1974 models will be necessary to provide the needed clearance. A fan shroud will maximize the effectiveness of the fan. Also, make sure that your radiator hose that connects to the coolant pump has fairly rigid walls as softer ones can collapse and restrict coolant flow at higher loads, resulting in hot running and even overheating.
Steve S.

Steve; The radiator is new as is the oil cooler and there is a blanking plate in place of the thermostat. The fan is original and in correctly and there is also an electric fan. I'm sorry I did not mention this before. This is the reason that i believe it might be the adjustable timing gear as I did not have a lot of cooling problems before. I just don't know where my thought process got off track.
Thanks,
Ed
E kulick

Ed-
Not all radiators are created equal. Some of the replacement radiators for MGBs are truly awful pieces of junk. Where was yours made? Also, a blanking plate on a street machine isn't a very good idea. The thermostat maintains the running tolerances of the engine and thus prolongs the engine's lifespan. The only advantage to using a blanking plate is that there's no thermostat to stick in the closed position and overheat the engine. However, you need to understand that a blanking plate is intended for racing use. In racing, the pulley sizes are reduced so that the pump will turn more slowly and allow the coolant sufficient time to absorb heat from the block and release it through the radiator. On a street machine, installing a blanking plate while leaving the pulleys the original diameter usually results in hotter running, which is confirmed by your experience. Install a thermostat.
Steve S.

I'd make the possibly silly suggestion to actually check the temperature gauge calibration with a kitchen type thermometer in the radiator neck. You can keep the car at idle and cover up the radiator to get the gauge into the same zone you're concerned about, then take a direct temperature reading. I chased this around a while until I discovered I was running at only about 200 degrees with the gauge in the 'red' zone.
Peter Van Syckle

Ed, A new rebuilt engine will normally run hotter than a worn out engine. Normally retarding the cam timing will move the power band to a higher rpm range. If you wanted low end power it should have been advanced a couple of degrees. Also if the cam is retarded too far it can cause overheating. Did you degree the cam with a degree wheel? If you relied on the cam to be accurate and then retarded it some more you could be several degrees off unless the setting was verified with a degree wheel. Are you using a stock cam? Stock cam timing for a 64 is around 2.5 degrees retard.

I have to agree with Steve S on new radiators not all being equal. I've been through the three row made in UK radiator and they don't cool enough on our 90 degree days. You need a four row staggered core radiator. Good luck, Clifton
Clifton Gordon

This thread was discussed on 06/07/2003

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