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07-30-2021, 10:09 AM | #1 |
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Can't get engine started after changing timing gear
This past week we changed the timing gear in our Special Coupe. I have only been able to start and idle it three times and drive one time since then. The following is a list (not exhaustive) of things I have done so far.
1. Changed out carburetors (three of them). There is adequate fuel flow at the carburetors. 2. Put in new "modern" points and the condenser, and set them to 0.018-0.019. 3. Cleaned and re-gapped the spark plugs to 0.035. 4. Set the timing according to Les Andrews in the Model Mechanics Book. I also consulted various YouTube videos on the subject. While setting the timing, I made sure I rotated the cam clockwise before tightening the screw. I used an indicator light which was off at notches 0 and 1 on the spark advance lever, and on at notch 2. 5. Double checked, and cleaned and tightened all wiring including the coil to distributor wire and the wiring in the terminal box. 6. The distributor has "modern" Nu-Rex plates in it. I checked the wire between the plates for shorts, there were none. 7. The three carbs are a Tillotson, a loaner Zenith, and the original Zenith that came with the car. I know the Tillotson may have clogged jets. 8. I have tried various GAV setting on the carbs. 9. There is the perfunctory 6.3 volts at the terminal box, the red wire, the starter, the alternator, and the points. 10. When we installed the timing gear three people checked, double-checked, and triple check the meshing of the timing gear and the crankshaft gear. 11. The ignition cable is turned into the distributor the correct amount. (I have no reason to believe otherwise because there is spark at the points, is this a correct assumption?) 12. The timing gear was not shredded, and the fibers were intact. So I imagine that nothing from the timing ended up elsewhere in the engine. Behavior 1. The engine turns over all right, but I am running down the battery. I was able to start the car one time and drive it around the block using the Tillotson carb, but I barely made it back home because the car was sputtering so badly. I imagine the sputtering could be from the clogged jets in the carb. Additionally, I was able to start it for about 30 seconds using the loaner Zenith and the Tillotson, but not yet with the original Zenith. 2. The engine backfired so loudly it sounded like a gunshot, and stopped. I could not restart it right away after that. 3. The engine sounds like it can catch, firing a couple of revs and then stopping 4. Before driving the car around the block on the Tillotson and while idling it, the engine sound was the best I have heard out of it. The idle was much quieter than before. I wonder what am I doing wrong. Is there a something I am missing? Is the above behavior indicative of a timing gear not in sync with the crankshaft gear (off be a tooth)? I don't imagine that is possible because I have been able to start it and idle it at least one time. I want my car back. Before the timing gear went out, the engine would fire almost instantly after I pressed the starter button. It is darn frustrating not being able start it. Bill Last edited by philcobill; 07-30-2021 at 10:29 AM. Reason: wording change |
07-30-2021, 10:34 AM | #2 |
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Re: Can't get engine started after changing timing gear
What happens if you try setting the spark control rod at different settings while starting? Does the behavior change at all?
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07-30-2021, 11:22 AM | #3 |
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Re: Can't get engine started after changing timing gear
The cam gear can be off 1 or 2 teeth and the engine may start and run but run poorly. Recheck the timing gear alignment.
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07-30-2021, 11:24 AM | #4 |
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Re: Can't get engine started after changing timing gear
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07-30-2021, 12:20 PM | #5 |
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Re: Can't get engine started after changing timing gear
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07-30-2021, 12:31 PM | #6 |
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Re: Can't get engine started after changing timing gear
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Since the car was running fine before you worked on it, I think that whatever you did caused the problem. So it is highly likely that there is a problem with the cam gear alignment. Bob |
07-30-2021, 11:55 AM | #7 | |
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Re: Can't get engine started after changing timing gear
Quote:
Just for a sanity check, is there someway to check before taking the engine apart in case it ends up being unnecessary? Last edited by philcobill; 07-30-2021 at 12:19 PM. |
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07-30-2021, 12:19 PM | #8 |
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Re: Can't get engine started after changing timing gear
I did not have it running long enough to determine this well. When I drove it around the block, I concentrated on just keeping it running when it was sputtering, and was playing around with the GAV control mostly.
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07-30-2021, 12:24 PM | #9 |
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Re: Can't get engine started after changing timing gear
I'm talking about adjusting the advance lever while you're trying to start it. If the timing is off, either due to a bad gear or something else, you'll sometimes see it start easier if you put the advance lever in a position where normally you wouldn't put it. Just something to try.
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07-30-2021, 11:22 AM | #10 |
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Re: Can't get engine started after changing timing gear
Check compression and post results.
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07-30-2021, 11:52 AM | #11 |
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Re: Can't get engine started after changing timing gear
Compression is between 70 and 73.5
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07-30-2021, 01:11 PM | #12 |
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Re: Can't get engine started after changing timing gear
I asked this to help without having to remove front cover again. Tooth mis-alignment will affect compression. 70# is high. I think too high for a stock engine/cylinder head. Is there a chance that the crank was turned while the original gear was off, before the new one was put on ? There were some gears quite awhile ago with the dimple in the wrong position. Try removing the sparklers and confirm TDC in #1 with the dimple in place. You see feel the piston top with a piece of wire stuck in the hole at an angle. Just be sure to not feel a valve moving instead.[ that has happened] Last edited by Patrick L.; 07-30-2021 at 01:32 PM. |
07-30-2021, 05:42 PM | #13 | |
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Re: Can't get engine started after changing timing gear
Quote:
Great suggestions! Yes, the cylinder head is made of aluminum. I am not sure what is the compression ratio, but it is certainly higher than the stock 4.22 to 1, perhaps it is about 5.5 or 6 to one. |
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07-30-2021, 11:34 AM | #14 |
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Re: Can't get engine started after changing timing gear
Do you have a spare known good distributor to install?is the battery at full charge?
Carbon tip in distributor cap good?ground to engine with an auxiliary cable? |
07-30-2021, 11:53 AM | #15 |
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Re: Can't get engine started after changing timing gear
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07-30-2021, 12:20 PM | #16 |
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Re: Can't get engine started after changing timing gear
When looking down #1spark plug hole find the spot that both intake and exhaust valves are slightly open( put in 3 rd and move some till one valve opens other closes, move till they are in "balance ", at that point the piston should be at top center---- this works for most internal combustion engines----- if cam is retarded power will be low, usually a lot of intake noise, and the ignition has to be over advanced
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07-30-2021, 12:24 PM | #17 |
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Re: Can't get engine started after changing timing gear
Phil,
There is a way to check the valve timing without taking the engine apart. Also the ignition timing without depending on the timing pin in the front. You have to go back to the basics of how an engine works. Here is how. Take the spark plugs out. Turn the engine over by hand until the timing pin inserts into the dimple in the cam gear. Now, verify that the number one piston is actually at top dead center by inserting a piece of wire or wood to reach the top of the piston and then rocking the engine forward and back with the crankshaft pulley. Depending on how stiff your engine is you may need a wrench on the crank shaft pulley nut. Once you verify that the #1 piston is actually at TDC then proceed to check the valves on #4 cylinder. Both intake and exhaust valves should be just barely open. If the timing pin did not accurately indicate TDC or the valves were not both barely open when #4 was at TDC then the cam timing is off. This could be due to a number of causes, perhaps a manufacturing flaw.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
07-30-2021, 12:29 PM | #18 |
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Re: Can't get engine started after changing timing gear
Something with your new timing gear doesn't sound right. Why did you change it?? Was something else starting to go south leading you to change the timing gear?? Compare the old one to the new one. Any differences?? Do you have a nice blue spark out of the coil when cranking the engine?? The spark may look good when flicking the points but cranking the starter might be dropping the voltage too much to provide sufficient spark.
Good gas?? |
07-30-2021, 04:14 PM | #19 | |
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Re: Can't get engine started after changing timing gear
Quote:
Yes, the spark looks good. |
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07-30-2021, 01:04 PM | #20 |
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Re: Can't get engine started after changing timing gear
One other thing. Do you have good fuel flow into the carburetor??
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