Tiny screws to plug off vacuum hoses Directions:
1) Shut off your car, let it cool off for about 5-10 minutes with the hood up
2) Hook up your timing light to the negative and positive terminals of your battery. Hook up the timing wire to the #1 spark plug wire. There should be a tag on your light's wire that has an arrow saying "Arrow Towards Plug" or something to that effect. Make sure all of the wires are well away from any belts!
3) Prepare the distributor to be moved by loosening off the distributor's hold-down clamp on the passenger side. You'll see the clamp pressing down on the base of the distributor, it looks like a "V".
4) Remove the vacuum hose from the carburetor and put one of the screws into the tube. If you don't have a screw the right size (it should be just a smidge larger than the inside diameter of the tube so it don't fall out) use a small Philips screwdriver. Place a vacuum cap over the vacuum port on the carburetor so you don't have a vacuum leak.
5) Start your car.
6) Aim the timing light at the front of your motor down towards the very bottom of your motor. You will see the harmonic balancer turning. If you can't find it, look for the timing mark coming off of the front of the timing cover, it is a tag that should have graduated marks starting at 8 and going to 0. The highest number should be an 8 or 10. This is called BTDC (Before Top Dead Center). Advancing the timing towards that direction is called "advancing the timing" whereas moving it away towards the smaller section would be "retarding the timing".
7) Look up on the underside of your hood. If your car has never been repainted you should see a sticker that will tell you what the stock timing should be set at. On most Chevy engines it is 6BTDC or 6 degrees "Before Top Dead Center".
8) If your timing is ATDC (After Top Dead Center) or past the 0 mark (on the right side of it) you need to advance your timing. Go to the passenger side of your car and with the rubber glove on turn the distributor cap a little bit COUNTER-clockwise. Go back and check where the timing mark is. If the mark is hard to see turn off your engine and wipe off the timing mark on the timing cover and wipe off the harmonic balancer where the line is on it and start your car.
9) Once you feel you are close enough to the setting you want, turn off the engine. Retighten the distributor hold-down clamp. Reconnect the vacuum hose from the distributor to your carburetor.
10) Take your car for a drive around the block. Stomp on the gas hard and listen for "ping". It will sound like your motor is rattling. If you hear it, back your timing off by turning your distributor CLOCKWISE a bit. "Ping" is a precursor to engine damage, you want to avoid "ping" or "pre-detonation" as much as possible.
11) If you are going to readjust your timing you should again loosen the distributor, cap the vacuum advance hose from the distributor, and put a cap on the carburetor. Do your adjustment and then put everything back together by reinstalling the vacuum advance hose and retightening the distributor.
Reproduced with permission from GMperformance.org
Edited By: 92SonomaST
