Good afternoon.
Sorry to be pestering about this problem, but i am still drawing blanks.
series 3 2.6 litre straight six. i rebuilt carbureutor, put new set of points and condensor and the motor is in excellent mechanical condition. it is getting a good strong spark from each cylinder and the vacuum advance is working. when motor is revved, timing advances by about 10-15 degrees. but the problem remains, the manifold is still glowing red hot after about 10 mins of driving at 80ks an hour on flat.
i have played with timing, tried it from about TDC all the way through to 20 degrees BTDC, played with the mixture, all the way from lean as it will go to just before the setting screw falls out. at settings, the motor runs reasonably smoothly, but still has the glowing manifolds. the motor is still staying within it's normal operating range, which is quite cool.
the one last thing i can think of is fuel. it is built to run on leaded fuel but up til now i have been running it on unleaded without putting any additive into it. i know i'm probably gonna cop a bit of flak for this, but i was under the impression that running it on unleaded would simply accelerate valve wear etc. a friend told me that it can infact cause the valves to get hotter, thus causing the manifold to get hot.
so my question is thus, will running a motor designed for leaded on unleaded cause the exhaust manifold to get extremely hot??
if so, i will fork out the extra 10 cents per litre for the premo unleaded. grumble grumble. but i will putting it on gas soon anyway!!
/thanks in advance.
Sam.