Visit The Dirt Forum for More Information

Author Topic:   timing again
Whitelightning
Dirt Maniac

Total posts: 102
posted January 11, 2003 06:55 AM
ok i have read all the post in the other forum but still have a question. When you get the number 1 piston up on the compression stroke that should be 0 right.

eddie7232
Dirt Full Roller

Total posts: 26
posted January 11, 2003 03:13 PM
I believe soo. but making sure that you have the the compression stroke up is the hardest part. One guy said to get piston up on both strokes and in the middle is tdc.

Eljojo
Dirt Freak

Total posts: 273
posted January 11, 2003 07:19 PM
Whitelightning, 0 degrees of timing means that the spark plug fires at exactly the time the piston is at top dead center(TDC).
You better start frome square one and get this done right...
There are two different kinds of timing; valve timing and ignition timing. You can adjust valve timing only by changing the relationship the camshaft has to the crankshaft. This is called advancing or retarding the cam. It's done with a degree wheel and a dial indicator. i.e. Degreeing the cam
The other timing is ignition timing which is adjusted by loosening the distributor hold-down and turning the distributor.
If you've had the distributor out of the engine, you'll want to pull the valvecover and watch the rocker arms as you rotate the motor by hand. As the harmonic balancer starts to approach the timing pointed you'll see the intake valve close and you'll know that you're on the compression stroke. Look at the end of the distributor that the gear is on and you'll notice there's a straight blade. That's what turns the oil pump shaft.
You may have to turn the oil pump shaft with a screwdriver (down thru the hole in the intake manifold) to get it aligned so that the distrubutor will drop all the way down into place WITH THE ROTOR BUTTON POINTING FORWARD TO THE # 1 CYLINDER. Now you know that you will be able to "time" the engine.Go ahead and hook everything up and start the motor. (this shouldn't take a whole lot of twisting on the distrubutor, because-when you snugged the hold-down you were paying attention to the location of the #1 plugwire and set it at the point where the rotor was.) Fire that mutha up and proceed with adjusting the ignition timing in the manner indicated in the pervious post.

Flatlander
Dirt Freak

Total posts: 310
posted January 12, 2003 09:48 PM
just a note at #1 TDC neither valve on # 1 will not move when the piston is up on any other one valve will move

[This message has been edited by Flatlander (edited January 12, 2003).]

WillieWinn
Dirt Roller

Total posts: 19
posted January 12, 2003 10:06 PM
This is getting In-depth!! These guys are right. Top dead center is paramount. Balancers can slip and the mark may not be correct. Also accounting for degreed cams changes marks. A motor is timed where the firing event is advanced or ahead of the piston reaching tdc because it takes time to fire and for fuel to burn. By the time you get this explosive event to push on the piston, the piston has traveled up to tdc and just beyond, this making it easy to push down. That's why a motor too advanced kicks back or locks, the piston is caught before it "climbs the hill" and the explosion trys to send it down backwards. Things like nitrous make the explosion quicker so you run less advance to compensate.

Back to the Archives