Re: Engine Does not want to "Pull"

Posted by DJ.Voyce on May 26, 1998 at 12:18:31

In Reply to: Engine Does not want to "Pull"
posted by Ken Bighamon May 26, 1998 at 06:31:51

G'Day Ken,
The good news is your problem could be some stupid little problem which can be retified in about 30 seconds by you once its been "diagnosed". This stupid looking word which seems to be a cross between a line drawn between two corners &something sniffed out is the be all & end all to the solution of most problems, be they mechanical or physical. The bad news is you might have to spend an inordinate amount of time groping around in the dark, which is not that much fun when it involves items of a mechanical nature as opposed to !---- but I digress.
It would seem that you've tried all the logical avenues so lets try a couple more. Take a run on a quiet road & when the power feels like it's "falling off", keep going for a few hundred yards more then kill the ignition & tramp on the clutch pedal at the same time & coast to the side of the road. This is known in racing circles as a plug chop & the object of the exercise is to ascertain whether the air-fuel mixture is correct by the colour of the porcelain insulator in the spark plug, so obviously it necessitates the removal of one or more spark plugs. Now comes the "rocket sceince" in reading the plug colour as this determines how the engine was running when you "killed" it.
If the inside of the plug has a creamy white colour then the mixture was too lean, or there was too much air & not enough fuel.
If the inside of the plug is black & sooty, then obviously the reverse applies as the engine was running too rich.
The correct colour, as explained to me by a then old & now long gone journeyman, "should be the colour of a coloured girl's nipple", but I've never been able to find this colour on any colour chart & as I'm averse to being slapped across the face, I've settled for a creamy brown or beige colour which I imagine must be pretty close.
If you've tried different carbs & the plug readings indicate a lean mixture, it could be:-
a) A fuel feed problem which could be eliminated by feeding fuel directly to the carb out of a container.
b) A valve timing problem caused by incorrect assembly or an incorrect timing gear with the keyway cut in the wrong position.
c) A blocked exhaust system causing excessive back pressure.
Good luck & happy hunting.
Regardz
DJ.
OutOfAfrica A's


: I have an engine which was rebuilt last year as part of my frame off resoration. The motor has only 100 miles on it and is still tight. The engine runs at idle very well. However when you start to run it out on the highway it seems to "fall off"
: after 40 MPH. I have changed the coil, condensor, I have run 3 different carbs and also double checked the manifold and carb to intake gasket. I've loosened the gas cap to make sure it doesn't have a vacum etc. I've not checked the valve clearance yet...but don't think that is the problem.

: Last night I noticed that when the car is FULL of fuel the problem nearly goes away but when the tank gets to 1/4
: the problem starts to return ?What am I missing?




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