Burnt Rotor

coltarms · Post by **coltarms** » Thu Feb 02, 2006 5:00 pm

Hi All! Last time I did a tune up my cap and rotor was all burnt up. The points looked ok. I replaced the cap and rotor. That was last August. Any ideas on why they were charred? I was getting around 28mpg right after the tune up, now i'm back down to 20ish. I'm going to check it again, along with rebuilding the carb, but I just thought I'd pick peoples brains first......

Dave

brianp · Post by **brianp** » Thu Feb 02, 2006 7:08 pm

When I replaced mine last fall, the points and rotor were just worn, not charred. I would think that it could get charred if there wasn't a very good connection between the rotors and the points, thus causing excessive sparking. I think I'd be surprised if you find that they are charred again on the new one.

Chris · Post by **Chris** » Mon Feb 06, 2006 1:58 pm

Points? I didn't realize that North American Tercels had points. I thought they all had the IIA ( Intergrated Ignition Assembly)

brianp · Post by **brianp** » Mon Feb 06, 2006 2:27 pm

Yeah, that's what I have. I guess I don't exactly know what points are then.

I was referring to the 4 different contacts on the inside of the distributer cap that go to the spark plugs.

Chris · Post by **Chris** » Mon Feb 06, 2006 3:09 pm

Don't be embarrassed. Points are an electro-mechanical devise for firing the coil. They are opened and closed by a cam on the distributor shaft located below the rotor. As to why your cap and rotor were charred..I don't know....sometimes they don't hold up well to all the spark they have to handle. Moisture under the cap might play a role.

As to your poor mileage...I strongly urge people to do a wet and dry compression test as this could give you a clue as to the engine's basic condition. Also check the ignition's timing advance. Check both vacuum advance diaphrams and the mechanical advance. Go thru the emission controls as they could affect the drivability. power and mileage. Other things to do/look for are.... cleaning and checking the functions of the external components of the carb (choke, choke opener, choke breaker, choke heater, etc.)....valve adjustment...make sure your brakes aren't dragging...tire pressures are not too low...etc.

I would do these things before tearing into the carb.

Hope this stuff helps.

coltarms · Post by **coltarms** » Mon Feb 13, 2006 12:35 am

Well, I did a quick compression test. All 4 cylinders read within 5 psi of 150. All the plugs were clean and seemed to be burning well. Looks good to me. I also tightened all the bolts on the carb....some were almost a full turn loose. I still plan on rebuilding the carb as it seemed to be leaking fuel around the base and at other spots.