300 timing mark disappeared
#1
300 timing mark disappeared
Hello everyone:
After I rering the pistons, and while I am timing the engine, I could not get the timing mark on the crank pulley aligned with the mark on the timing gear cover.
When moving the distributor, the engine responds but the mark seems to be far down and will not come close.
I adjusted the idle to specifications 550 RPM. the engine starts and runs fine, just the timing mark is the problem.
Wish anyone can shed some info and I will be grateful. Thanks.
After I rering the pistons, and while I am timing the engine, I could not get the timing mark on the crank pulley aligned with the mark on the timing gear cover.
When moving the distributor, the engine responds but the mark seems to be far down and will not come close.
I adjusted the idle to specifications 550 RPM. the engine starts and runs fine, just the timing mark is the problem.
Wish anyone can shed some info and I will be grateful. Thanks.
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#8
You can experiment with an alternative method by setting the initial ignition timing at the distributor by using a mechanic's vacuum gauge (connected to a source of manifold vacuum); rotate the distributor clockwise until the highest steady vacuum reading is achieved while engine is running at factory idle RPM in neutral. Then back off just slightly from this number. A healthy stock engine with good piston rings should idle at 18" to 20" of steady vacuum at Sea level. This will be very close to the optimum ignition timing. As always, ignition timing is set with the vacuum advance port on the carburetor disconnected and plugged. When you are satisfied with the mechanical ignition timing reconnect the vacuum advance for further vacuum advance tuning.
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#11
Problem is, it doesn't take much of a turn or movement of the distributor to throw the timing WAY off if you're not careful. About the width of a pencil line equals 2°. You can try advancing in slight increments, go for a quick test drive, until you notice ping or engine knock on heavy acceleration, and back off from that point. Again make sure vacuum advance is disconnected and plugged. The old timers had some methods of "power timing" that work pretty good, but we'll just leave that to the readers imagination.
The real answer is to determine exact TDC of the number 1 piston and scribe this point on the damper if there is a question about the accuracy of the current TDC mark. Install a timing tape on the damper and use this for timing engine using a light.
The real answer is to determine exact TDC of the number 1 piston and scribe this point on the damper if there is a question about the accuracy of the current TDC mark. Install a timing tape on the damper and use this for timing engine using a light.
#12
do not adjust the distributor to achieve your idle rpm. idle rpm adjustments should be made between your curb idle speed adjustment screw and idle mixture screws on the carb.
ignition should be first when tuning, before road tests...to include timing. it can accurately be done with a vacuum gauge, or a timing light. make sure you're using the correct index mark on the damper, along with the correct pointer on the engine when using a timing light.
it can be done by ear, sort of...but it takes several gentle adjustments, and a lot of time. its nowhere near as precise as a light, or vacuum gauge. I know it can be frustrating having a shortage of tools or parts...but your vehicle will never operate to its potential, and you run the risk of other problems, unless you can accurately assess it's condition and properly tune it. if you can find one online, I'll politely suggest that you invest in a vacuum gauge.
ignition should be first when tuning, before road tests...to include timing. it can accurately be done with a vacuum gauge, or a timing light. make sure you're using the correct index mark on the damper, along with the correct pointer on the engine when using a timing light.
it can be done by ear, sort of...but it takes several gentle adjustments, and a lot of time. its nowhere near as precise as a light, or vacuum gauge. I know it can be frustrating having a shortage of tools or parts...but your vehicle will never operate to its potential, and you run the risk of other problems, unless you can accurately assess it's condition and properly tune it. if you can find one online, I'll politely suggest that you invest in a vacuum gauge.
#14
Hamid,
Without a vacuum gauge or timing light, let the engine idle once it has warmed to operating temperature. Remove the vacuum line from the distributor canister and plug it with a golf tee or something similar. Take a 1/2" wrench and loosen the distributor hold down bolt just enough so you can rotate the distributor. BE VERY CAREFUL FOR MOVING PARTS!!! When rotated clockwise, timing will be retarded and the engine will slow down. Rotating the distributor CCW will advance the timing and the engine will speed up. Once the engine "sounds right", tighten the hold down bolt and then proceed to adjust the idle speed and air/fuel mixture screw. Don't forget to reattach the vacuum line to the distributor canister.
Take the truck for a drive and accelerate under a moderate load. Listen for a pinging sound [pre-ignition]. If this is heard, stop and shut off the engine. Loosen the hold down bolt while holding the distributor cap... just barely rotate the distributor CW. Tighten the hold down bolt and drive again. Continue this process until the pinging disappears or is just barely audible under moderate load.
Without a vacuum gauge or timing light, let the engine idle once it has warmed to operating temperature. Remove the vacuum line from the distributor canister and plug it with a golf tee or something similar. Take a 1/2" wrench and loosen the distributor hold down bolt just enough so you can rotate the distributor. BE VERY CAREFUL FOR MOVING PARTS!!! When rotated clockwise, timing will be retarded and the engine will slow down. Rotating the distributor CCW will advance the timing and the engine will speed up. Once the engine "sounds right", tighten the hold down bolt and then proceed to adjust the idle speed and air/fuel mixture screw. Don't forget to reattach the vacuum line to the distributor canister.
Take the truck for a drive and accelerate under a moderate load. Listen for a pinging sound [pre-ignition]. If this is heard, stop and shut off the engine. Loosen the hold down bolt while holding the distributor cap... just barely rotate the distributor CW. Tighten the hold down bolt and drive again. Continue this process until the pinging disappears or is just barely audible under moderate load.