QuestionQUESTION: Howard,
Before I invest in another test tool (vacuum), there is no CAT and I have a Weber downdraft manifold, cleaned the servo check valve that was full of trash with no results.
While starting the car myself (instead of wife) I notice the ignition light stays on while engine trying to run. Let run to heat up, but started to backfire through carb really bad.
Keep in mind I didn't have this problem until the car overheated.
Thanks,
Scott
ANSWER: Over heating an engine does several things like take the temper out of the rings so they can not keep pressure on the cylinder walls. However, if you have a good compression test that may not be a problem on your car. The next thing that overheating does is to take the temper out of the valve springs, usually starting on the center two cylinders. This is easy to check. Remove the valve cover and with both thumbs push down on the front and rear valve springs to note how hard it is to just move a little. Now do it to the valve springs on both center two cylinders. If you can tell any difference by hand that could be your problem.
You don't need to purchase the vacuum gauge if the CAT has been removed because overheating can send a lot of raw fuel into a CAT and destroy it and thus partially stop up the exhaust.
A valve that will not close quickly due to a weak valve spring can give you the problems you have so check them and let me know.
Howard
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QUESTION: Howard,
Finialy got time to check the MGB valve springs, don't see all that much difference. Should still replace? Moss has the HD single springs for around $60. Should I pursue the double ones like I have if I replace?
Also know the rope trick so as not to have to remove the head.
Going to Africa soon for a couple of months on business, so would like to get this resolved before I leave.
Thanks for your input,
Scott
ANSWER: If the front spring and rear spring feel the same as the springs on the center two cylinders and you can barely move them with two thumbs, there is no use replacing them. A valve spring needs to be very weak to cause an engine not to rev much over idle.
If that is the case you have some other problem and you need to start from scratch and run a compression test and set the timing and check for fuel available to the cylinders by spraying extra fuel into the intake while trying to rev the engine.
Howard
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QUESTION: Howard,
Went all over the wiring today, and checked the timing.
Got it running better (ignition red light off). I turned the motor until the distributor peg was on number one cylinder and marked (no marks on flywheel). Checked with strobe and marks are way off, turned distributor until running smoothly, but marks are out of sight.
Must have jumped timing when it got hot, like I said before I replaced the electronic distributor with new. Put the new in same position as the old I took out.
Scott
AnswerScott, the timing must be set accurately and must never be adjusted away from specs to make an engine run better.
You need to ID the timing marks. To do this you need to remove all of the spark plugs and get a piece of wire like a coat hanger. Put the car in 4th gear on flat ground and put your thumb over #1 plug hole as you role the car forward. As soon as you feel compression on your thumb stop and put the wire straight down into the #1 plug hole to feel the top of the piston. Then role the car forward as you note the movement of your coat hanger as it comes up. Move the car slowly until you have found TDC (top dead center)of the piston. If you have to move the car back and forth a little at the top to get it as close to the top as possible, then don't move it. Look at the front crank pulley and note a notch in the outter rim of the pulley and it should be lined up with the longest pointer on the front cover. If it is close move the car to get it lined up exactly and remove the distributor cap and note if the rotor is pointing toward #1 pin in the cap that has #1 wire. That may not be exact because the engine does not fire at TDC. But it should be close.
If for some reason there is no notch in the pulley you need to check with the coat hanger as accurately as possible that the piston is at exact TDC and then go down on the front pulley and either paint and small mark opposit the long pointer or use a sharp chisel to mark the front pulley.
Then you can set the ignition timing with a strob light to specs.
The ignition red light is not an ignition light, but is a charge light. Don't ask me why. Some Englishman was drinking that day when they decided to call it a ignition light.
Howard
