Ignition timing - odd behavior |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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Posted: July-15-2018 at 5:22pm |
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I been working through a series of issues with my 1978 Mustang 17 (Ford 302), and had some postings last year. At this time, I'm working to get engine running after having it re-built (2017 winter) and re-assembled (within the last few weeks). I'm a novice, so I'm doing the best I can with information that I can find.
I believe that the engine and most components are in reasonably good shape. Engine will run, but it is behaving strangely. Recently, I have done the following: [a] attempted to get distributor in proper alignment by having engine at TDC with rotor pointing at spark plug #1 (and I have checked/double-checked firing order, spark plug wiring). I'll call this position A. At position A, I can't get the engine to start, not even close! The only way I can get engine to start is to rotate distributor clock-wise about 1/2 the distance to the next spark plug post in the distributor cap. I'll call this position B. At position B, the engine will start consistently, but it idles fast as ~1600 RPM (carb idle adjustment will not reduce idle speed). And, when I try to get timing reading I find that it is off the scale completely. So, then I adjust distributor in counter clockwise rotation and when I get back to position A I find that: (a) I can get idle around 1000 RPM, and (b) I can get a timing reading, (c) and I can fine-tune positioning to get a good reading at 12 degrees. In other words, everything seems fine (as best I can tell) at Position A. But, engine WILL NOT start at this position. Does this indicate some issue that I need to fix? I'm thinking it is something obvious to folks who know engines... I am looking for a local mechanic that can set my timing as I expect an experienced mechanic will understand what I happening (I don't). |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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We have no idea where you are |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Gary,
Is the mechanical advance free to move in the distributor? They will rust up. |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Gary, I found Gary's location in a previous post.
Gary, What's up with Backyard Boats? Too "backyard" |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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[a] forgot to mention... I'm in northern VA (outside of Washington DC).
"mechanical advance free to move in the distributor": I don't know. I'll need to check that, but I'll first need to find the mechanical advance. I think I found you-tube video that will help... Gary |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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I checked the following for starts since it was fairly easy. Removed dist cap, and checked movement in the rotor. It will rotate/pivot a small amount (about 1/2 the distance between two adjacent contacts in dist cap), and is spring loaded to return to original position. So, I'm guessing that this is related to mechanical advance and indicates that it is not frozen. Unless, I need to do more, partially disassemble distributor to access mechanical advance ... ?
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Gary,
Since the rotor does move, it indicates the advance isn't locked up but, you don't know if the advance moves all the way. To check and lubricate, the point plate needs to come out since the mechanical is below it. |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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right, I figured I might need to remove that plate to get the complete story. guessing it is worthwhile to spend the time to look into this further. Will look at this Monday (tomorrow).
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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I checked the movement of the mechanical advance. They are not frozen/bound, and I did lubricate lightly. But I did noticed that the two springs are not a matching pair. One on right is light (almost as light weight as you would find in an old pen) and is engaged/tight. The one on the left is much heavier, and quite loose. Not sure it this is as it should be, or if it is a potential issue.... Attaching picture:
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Gary,
The springs are normal. |
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Gary - Your timing light issue may be because of spark plug wire position.
TDC mark on harmonic balancer comes around twice, so maybe it was not on correct part of cycle. Also, are you calling #1 as the front starboard plug? Sorry if this info is too basic. Hope you get it figured out soon! |
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“Beer is proof that God loves us and wants us to be happy.”
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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Not too basic, and I appreciate all comments/ideas that I get. Yes, I am considering front starboard plug as #1.
I should have mentioned that I have not confirmed that I have the correct cycle. My machinist said he delivered the engine at TDC. I've been meaning to check this as well. I'm planning on using the wood dowel method. |
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gt40KS
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OR the thumb over the #1 plug hole method ... which ever works best for you
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JCCI
1995 Ski Nautique GT40 |
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Just keep in mind that the wood dowel won't tell you when both valves are closed. The thumb method would be positive on that.
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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Ok, didn't realize that - thanks!
So, if I do have the true TDC and spark plug #1.... then I'm still lost in terms of what I'm seeing when starting/running this engine.... Anyone else ever run into this situation? |
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KENO
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What is your firing order?, you mention that you've double checked it but never have said what it is.
Are you saying the rotor is pointing at the terminal you're using for #1 plug wire or that it's pointing at the #1 spark plug? The rotor can point anywhere and as long as it's pointing at a terminal in the cap that terminal becomes #1 If the rotor is in between terminals, rotate the body of the distributor either way till the rotor is pointing at a terminal and that's your #1 and then you install your wires going CCW from there following the correct firing order.. The rotor doesn't have to point at #1 plug on the engine like some instructions will tell you. It's one of those things that's harder to try to explain that it is to do for the first time. |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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ok, my firing order is: 18456273 (per plate mounted on engine).
right, in what I called Position A: rotor is pointing to distr cap terminal for spark plug #1. I have it pointing directly at #1 with engine at TDC (I still need to do the check to make sure I'm not off by 180 degrees). Engine refuses to start in this position, and only starts if I rotate it CW to be about 1/2 way to the next spark plug terminal. But at that position (my Position B) the engine doesn't run correctly (idle speed, timing, etc.). |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Online Points: 10703 |
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It all sounds good.
It's the right firing order for a 78 ish 302, if by some chance you ended up with an early 302 cam during the rebuild you'd have running issues but not these wacked out timing indications.. When # 1 is at TDC on the compression stroke is the timing pointer pointing at 0 on the harmonic balancer? |
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garykocis
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So you've hit the right question. Following the earlier suggestion I did the 'thumb' test to find compression stroke on #1, and I am WELL away from 0 degrees. As best I could estimate, I am 1/3 of a rotation from 0 degree mark. In other words, if my 0 degree mark is at 12 o'clock, the compression stroke would have been at 4 o'clock on the harmonic balancer. How does this happen, what does it mean, and what can I do about it? I suspect it means the guy who re-built my engine did something wrong! Feeling nervous here...
I'll admit this was the first time I tried to find compression stroke with thumb over spark plug #1 opening. It was a fairly subtle amount of pressure, but I repeated it a few times to be confident that I was doing it correctly.... |
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garykocis
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just thinking through this process.... IF something is not aligned as it normally would be, then can I find which spark plug is on compression cycle when HB is at 0 degrees, and align the rotor to point at the corresponding contact in the distributor cap? or, is it more complicated than this....? then, set timing using that spark plug wire (instead of #1).
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MourningWood
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Here's another thing you can do to double check...remove the starboard side valve cover, and watch the cylinder #1 valves as you manually rotate the engine (the correct direction). When you see the intake valve close, the next time the piston is at the top of cylinder (firing position). you're at TDC #1 firing position. some folks then make a mark on the damper at the timing pointer. (which hopefully indicates "TDC" or "O". on the damper).
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1994 Ski Nautique "Riot"
1964 Dunphy X-55 "One 'N Dun" 'I measured twice, cut three times, and it's still too short!" |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Online Points: 10703 |
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I may have hit on nothing with that question. Don't feel nervous yet. Using the thumb over the hole method, you feel slight air escaping on the whole compression stroke and if you had air escaping for the last 1/3 of rotation sounds right. Using the thumb method all it really tells you is that with the air escaping you're on the compression stroke and you stop turning the engine when the pointer is at 0 on the balancer. In other words your thumb tells you that you're on the compression stroke, and in no way can you use your thumb to know you're at TDC without looking at the timing marks, or the valves like mentioned a post or 2 back or the distributor rotor. This assumes everything is correct, like the timing chain was put on correctly.with the timing marks on the cam gear and camshaft gear properly lined up. If you mark the distributor housing where your #1 terminal is on the cap, and do the thumb test with the cap off, you should see the rotor pointing to that mark when your pointer is aimed at 0 on the balancer. How about a picture of the pointer/balancer? I seem to remember reading that you have an electronic conversion, what kind is it? If it's a Pertronix is it the Ignitor (black module) or Ignitor 2 (red module)? |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21125 |
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I would pull on this thread a bit more. Ford used a few different pointer locations so if the balancer was replaced during the rebuild with one that mismatched your zero timing mark with your pointer location, that would have the effect you describe. Confirming the actual location of TDC with a piston stop would be a good idea. You aren’t 180 off if you have the correct firing order and the engine starts, FYI. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Online Points: 10703 |
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The best picture would be with #1 at TDC then you take the picture of the pointer/balancer
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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Thanks for all the useful comments/ideas. Yes, I have a Pert Ignitor (black). I will upload some pictures this evening (if my rain stops here).
Harmonic balancer and pointer are original (at least, I know they weren't changed in the recent re-build). I will pull the valve cover and find position where plug #1 valves are closed. I also have a dial caliper with a depth measurement so I should be able to accurately find the top of piston cycle (if I need to be precise).. I'm going to assume that this (with the thumb/air pressure) will let me find TDC. I'll take pictures, and mark this position on harmonic balancer. |
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garykocis
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First I'll add some comments, then two pictures. When engine is at 0 degree mark: I get a measurement of ~ 1.25 inches to the #1 piston. If I rotate 180 degrees, I measure 5.75 inches. I believe this is as expected. When I rotate crank shaft CCW, I get air pressure about 2/3 of a rotation before 0 degree mark. I can feel air pressure/leakage over a range of 45 degrees (I think). Depth to #1 piston is 4.75 inches.
First picture is HB scale when at 0 degree mark. I recently made the silver marks. The one yellow mark has always been there (since I owned the boat) at 12 degrees BTDC. In the second picture, I rotated a bit to show a piece of masking tape (near bottom of HB) which is where I get air pressure on plug #1. As you can see, it is ~1/3 rotation after 0 degrees or 2/3 rotation before. I'm working on valve covers next, might be difficult to get to this evening... Comments? |
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garykocis
Groupie Joined: August-15-2009 Status: Offline Points: 66 |
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Pictures....
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Online Points: 10703 |
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When you took this picture was #1 piston at TDC? Was the rotor pointing at the #1 plug wire terminal in the distributor cap? |
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garykocis
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Yes, #1 piston is at TDC...depth to piston through spark plug hole is 1+1/4 inches, and that is as close to top as I could measure. Darn, I got busy with valve cover, forgot to check rotor. I'll check that tomorrow (too tired, too dark).
After removing valve cover... got what I guess I expected. Intake valve #1 is closed when pointer mark is on the masking tape which is 1/3 rotation past 0 degree mark. You can see masking tape mark in picture #2. |
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garykocis
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wait a second... don't I have a big problem if both valves are not closed when #1 piston is at TDC???
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