> I have an overheating problem with my TR3 in the summer. It is worse when
> under hard load such as going up a long, steep grade. I have a
> new radiator,
> the thermostat has been checked and is of the original bellows
> type. It has
> 87mm pistons with a stock cam. I'm abto pull the engine and check that the
> valve timing is OK. Any ideas?
Dave, you can check the valve timing without pulling the motor :
First, double check that the mark on the pulley is accurate. To do this
you'll need a piston stop, which you can either buy
(http://www.cranecams.com/master/toolcmpr.htm is one source)
or make by knocking the ceramic out of an old spark plug, threading the
shell for a bolt, and grinding off the head of the bolt. Insert the stop in
the #1 plug hole, and turn the engine (gently) until it stops. Make a
temporary mark on the pulley under the pointer, then turn the engine the
opposite way until it stops again. Make a second mark, and verify that the
TDC hole is exactly half-way between the two marks you've just made.
Now remove the rocker cover, and turn the engine until both valves on #4 are
open slightly. Set the clearance on both #1 valves to about .030", The
exact number doesn't matter, as long as both are the same, and you can stack
feeler gauges if your set doesn't go that large. Now turn the engine
forward for one complete revolution, stopping exactly where the TDC hole
lines up with the pointer. It's important that you turn forward to this
point, so if you pass it, you'll have to back up and try again. Now measure
the clearances for the #1 valves. If both are equal, the camshaft is at 0
degrees. If the exhaust valve gap is larger, the cam is retarded. If the
intake gap is larger, the cam is advanced. You can expect some error,
anything in +/- 2 degrees is acceptable. If you turn the engine until the
two gaps are equal, you can estimate how much the error is by measuring
between the TDC hole and the pointer. Each 3/32" is roughly 1 degree of cam
rotation (2 crank degrees).
Some other things to check :
Make sure the timing is correct, not just the initial setting but that both
the mechanical and vacuum advance work.
If the carb jets and needles haven't been replaced recently, or you know the
jet centering was wrong at one time, replace them.
If you have the 'wide mouth' grill (ie 3A or 3B), be sure the cardboard
shroud in front of the radiator is in good shape. Some early 3A's didn't
have the shroud originally, IMO it's worth adding.
Check that the front lower generator mount is in good shape, both the bolt
and nut are tight.
Make sure your radiator cap is holding pressure. I don't know if radiator
shops can normally test these systems due to the unusual cap dimensions, but
they probably can. I tested mine by screwing a plumbing tee with a pressure
gauge and a valve stem into the heater outlet on the head. Added some
pressure with a tire pump, fixed leaks and worked on the cap until it would
hold pressure overnight. 4 psi is standard, I ran mine up to 7 psi using a
modified cap. (Not sure if this is a good idea with a heater, but since I
don't have one ... <g>) BTW, most vacuum test gauges will also read small
amounts of pressure, mine goes to 10 psi.
If all else fails, pull the water pump and check the vanes. BFE has
available a high efficiency 6-vane water pump that several people have said
helps.
Randall
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