leeloo67

Are the original timing gears made out of plastic on this car by any chance? Here is why I ask:

So the emissions fails this weekend with a reading of 226 (standard is 220). I hadn't set the timing with the light, and I never drive the car, so I wasn't really surprised by this. I take it home and the timing is off the scale at about 14 degrees (est) before tdc. I set it to 6 like the sticker says, and it won't hardly run at all. At 8 and 10 it will run, but will BACKFIRE if you push the gas quickly! This of course causes alarm because the engine should never backfire unless there is something going on with the valves. I set it to 12 before tdc and it seems to have plently of power, runs ok, and does not backfire. Does this sound like I am a timing tooth off to anyone?

I am about to sell this car, and I don't want to sell it with some kind of plastic timing gear about to go!

Thanks.

Fevre

Your balancer may have slipped. Only way to tell is to find tdc and compared it to the mark on the balancer. Do you have computer controlled timing?

Mr.Gearhead

LUCY.. Please esplain... How could a balancer slip? With 3 bolts and a center bolt? I am lost.

I am thinking... maybe slack in the timing chain? Did you unhook vacuum when shooting the timing? Backfire sounds fishy... change any plug wires? maybe at the cap? :confused:

leeloo67

I just did an intake job recently. I marked the distributor before disassembly, and moved nothing during the job! The car started within 2 seconds after reassembly.

The instructions on the underside of the hood said to disconnect a certain wire (tan with a black stripe), but there is no tan/black wire! I disconnected a tan wire (with no stripe), and the car shut off and would not start. So I just moved the distributor with everything connected and the engine at operating temp, set at 12 before tdc. I just drove it around, punched the gas and everything, and it sounds like it is running perfect and there is no backfire.

The thing is, my experience tells me there shouldn't be a backfire if all the timing parts are lined up.

Although I have been around car engines all my life, this is my first american car. I've had a Mazda, Toyota, 2 more Mazdas, another Toyota (Supra), then another Toyota, a rotary Mazda (no timing parts!), and a Honda. I need help with this current behemoth!

leeloo67

Took the car back for reinspection and the reading is now 156. It is actually running a little less than perfect set at the 12 degrees before tdc. It ran better when it was slightly more (off the scale).

I did some reading on the forum and it sounds like the gears are possibly cast with nylon coating. I just don't know if this engine would even run if the timing was off by one tooth. My old inline 6 Supra was off a tooth once on one of the cams and it wouldn't even start. The Corvette backfiring was the most disconcerting. Any ideas anyone has would be great.

Z-man

I'm not too familiar with the timing on a "new" car like yours. But for a standard small block Chevy, initial timing (no advance) of 10 - 12 degrees advance is common. At higher revs and fully advanced, the timing should be around 33-35 degrees before TDC.

comp

balancer slip.... the outer ring,where the timing mark is, Is bonded onto the
inner part that bolts to the crank. oil,time,etc. the bond can (and will)give

JB

Balancer's on chevy's slip all the time! (waaaaa, Ricky! :D ) The balancer is made of an inner disc and an outer ring. Between the outer ring and the inner disc is a band of rubber that absorbs vibration. The rubber gets old and gives, sometimes just slipping a bit (mine slipped about 90degrees), sometimes coming all to pieces and falling off or blowing up.

JB


[Modified by JB, 11:56 PM 5/25/2004]

Larry B.

The balancer is a two piece unit. The inner piece and a thin strip of rubber and then the outer ring. The outer ring can slip and in some cases come completly free from the inner part, so yes the can slip. When they do thenn the timing mark is no longer correct.. got.it?

MotorHead

I believe the only vehicle capable of juming time was the Delorean.

Garys '68

Just curious, what year is it and did you check timing with vacuum advance disconnected?