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corrected distributor time, no power now
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startech47
Jedi Knight
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How are you timing it? Have you confirmed that the timing marks are in the proper location?
dklawson
Yoda
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Did you set the timing dynamically (engine running) or statically? If you set it dynamically, did you disconnect the vacuum advance line at the distributor and plug it?
Keep in mind that to retard the timing is to move closer to TDC (fewer degrees BTDC). To advance the timing is to move the timing further away from TDC (more degrees BTDC).
Keep in mind that to retard the timing is to move closer to TDC (fewer degrees BTDC). To advance the timing is to move the timing further away from TDC (more degrees BTDC).
blkcorvair
Jedi Knight
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If youv'e got a good ear you can set it by linsening for engine knock. Keep advancing it and taking it for trips at highway speed, until you hear engine knock than back off a few degrees. Just dont lower your octane after doing so or you may have to retard it a bit more.
I have set the timing to where it runs and pulls the best, but (which it is @ about 28 BTDC). Is there any issues with doing it this way (harm to engine or other issues?) I am still getting only about 25 MPG which I think I should gett better milage. I did check the 0 TDC mark in comparison to watching the #1 cylinder with the spark plug removed. So maybe the other sprocket is off by a tooth then (is there an easy way to check this w/out removing the radiator and timing chain cover?).
I still think your distributor drive gear is in one tooth off. Make a mark with a magic marker or paint stick on the distributor body in line with #1 plug wire. With #1 at TDC, remove the distributor cap, and see where the rotor is pointing. It should be aimed nearly at the mark you just made.
Jeff
Jeff
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Am I missing something here? It seems to me that, if the gear is a tooth off, it shouldn't matter--it just means that, once you time it, the distributor body will be in a slightly different position. Or, to put it another way, if the gear is a tooth off, the distributor cam will be rotated a bit from the expected position. Then, when the timing is adjusted correctly, you just end up rotating the distributor body a little farther to compensate.
In the final analysis, if the plug fires, say, 10 degrees BTDC, and that's the spec, it's timed properly. Nothing else matters.
As for the original question, if you go from 20 degrees ATDC to something reasonable BTDC, and you don't see a dramatic difference, something is definitely very wrong. Not necessarily ignition, but maybe. Centrifugal advance, maybe?
In the final analysis, if the plug fires, say, 10 degrees BTDC, and that's the spec, it's timed properly. Nothing else matters.
As for the original question, if you go from 20 degrees ATDC to something reasonable BTDC, and you don't see a dramatic difference, something is definitely very wrong. Not necessarily ignition, but maybe. Centrifugal advance, maybe?
racingenglishcars
Darth Vader
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Correct Steve. It doesn't matter if the gear is a tooth off, as long as the distributor can be turned to the necessary position for correct timing.
Regarding correct timing. The factory gives specifications for the expected fuel, compression, atmospheric pressure, temperature etc. The MAJOR thing is that the highest rate of expansion of combustion happens during or slightly before the fastest movement of the piston on the power stroke. This is BEST achieved by adjusting timing for best power. -- When it runs best, the timing (at that power setting) is best.
Advance curves attempt to give more proper timing when the engine is not running full power. But don't be fooled. The best timing is when power is best, not when idle power is set at a pre-determined number.
Regarding correct timing. The factory gives specifications for the expected fuel, compression, atmospheric pressure, temperature etc. The MAJOR thing is that the highest rate of expansion of combustion happens during or slightly before the fastest movement of the piston on the power stroke. This is BEST achieved by adjusting timing for best power. -- When it runs best, the timing (at that power setting) is best.
Advance curves attempt to give more proper timing when the engine is not running full power. But don't be fooled. The best timing is when power is best, not when idle power is set at a pre-determined number.
startech47
Jedi Knight
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Pick one of the below items at a time and check them out:
The timing marks are off, caused by a replaced timing cover or crankshaft pulley
You are using the wrong marks on the crankshaft pulley or timing cover
The advance mechanism is frozen and not moving
The timing chain is worn out
The vacuum advance unit has a problem
To check the timing chain remove the valve cover and view a rocker that is partially open. Rotate the engine by hand or by pushing the car in gear both directions. With a tight chain the rocker will start moving almost immediately. With a loose chain you will be able to turn the engine before the rocker starts moving.
You need to Top Dead Center (TDC) the engine and confirm the timing marks are correct. Let me know if you need detailed instructions
With a timing light confirm the advance changes as you raise the engine speed with the vacuum advance disconnected
Put a piece of tubing on the vacuum advance unit, apply vacuum to the vacuum advance unit, confirm it has moved to it's fullest extent, pinch the tubing off, and confirm that the vacuum advance mechanism maintains it's position
Let us know what you find
The timing marks are off, caused by a replaced timing cover or crankshaft pulley
You are using the wrong marks on the crankshaft pulley or timing cover
The advance mechanism is frozen and not moving
The timing chain is worn out
The vacuum advance unit has a problem
To check the timing chain remove the valve cover and view a rocker that is partially open. Rotate the engine by hand or by pushing the car in gear both directions. With a tight chain the rocker will start moving almost immediately. With a loose chain you will be able to turn the engine before the rocker starts moving.
You need to Top Dead Center (TDC) the engine and confirm the timing marks are correct. Let me know if you need detailed instructions
With a timing light confirm the advance changes as you raise the engine speed with the vacuum advance disconnected
Put a piece of tubing on the vacuum advance unit, apply vacuum to the vacuum advance unit, confirm it has moved to it's fullest extent, pinch the tubing off, and confirm that the vacuum advance mechanism maintains it's position
Let us know what you find