Ignition timing - odd behavior

Well, too early to crack open the champagne... but - pulled my carb to take a look and found some fuel in places it should be! so, if gas is leaking out I'm sure there was air getting in. going to try a gasket tomorrow, depends on what I can get locally (or I'll order from natique parts and be patient for a few days...

MechGaT wrote: The engine will run at the correct timing, but it won’t start there. It will start with more advance and idles fast. Maybe you said and I missed it, but what’s the condition of your carburetor? When was it last rebuilt? We have been pretty far down the timing route, maybe it is like Ken frequently says “when you think it is ignition, look at the fuel.”

Funny that you mention that.   

I had a conversation with Gary and that's something that came up, it was rebuilt a couple years ago, but that doesn't mean much, a lot can happen in a couple years of sitting or use..

He gonna look at the rest of the ignition system first like the coil and also bypass his ballast resistor since it's got electronic. ignition

It does seem that he's done a very good job of verifying things as far as the timing.

One of those little voices keeps saying   vacuum leak vacuum leak (like a carburetor base gasket) and the higher rpm,s from the advanced timing let it start and run

He'll know his engine pretty well when this is over

That is a wise and logical idea. The one guy I could find to rebuild the engine would only work with the long block. I tore it down to that point, and got it to his shop. He said he only does the machinist work. And, I regret having this guy work on it at all (difficult to work with, communication, etc.). I have attempted to get some info from him, but unsuccessful. I'm open to have a trainer pro help, but it won't be that person.

I wanted to check the firing rotation which plugs were out. So, starting from TDC (where piston #1 is at TDC), I rotated the crank shaft 1/4 turn (8 times) and checked to see which piston was at TDC. I got the following:
0/4: 1 and 6
1/4 : 2 and 8
2/4: 4 and 7
3/4: 3 and 5

So, I conclude that this is aligned with the engine firing order, by working top to bottom and alternating left and right:
1 - 8 - 4 - 5 - 6 - 2 - 7 - 3

Eliminates the possibility of having the wrong cam shaft (I think)....

ok, so I was also having difficulty believing I was 180 out. I repeated the exercise with an assistant (yes, my wife) and I pulled all the plugs to make life easier. I think I was confusing a suction with a positive air pressure. So, with a helper we definitively found the compression cycle. once I had that, continued to 0-degree mark and I'm confident this is the correct TDC position. Checked rotor... it is pointing to distr cap contact for #1 plug.

So, after a bunch of diagnostic work - I am back to exactly where I was at the start. I haven't changed the distributor position at all. I'm convinced that I had correct initial timing position from the beginning. Don't have time to try it tonight, but I have no reason to believe anything is different from what I had initial posting a few days back. ???

garykocis wrote: Both of the #1 valves are not stiff (I can wiggle the rocker arm). I believe that both of #1 valves should be closed at TDC - right?

No cam/lifter pressure on pushrod means valves are closed.

Sounds like you just need to reset you plug wires & you should be good to go.

I think it is a miracle it ran at all, with plug wires 180 off!

No your right just assumed 😳 and you know how that goes.

I think your over thinking this....
What you could do pull all your wires off the cap. then where your rotor is pointing to is where the number one sparkplug wires goes to. Then follow your firing order and connect up the rest of the wires. Or the possibly more difficult way would be to pull the distributor out turn the rotor shaft to where you want it and drop it back in. Then again where the rotor points to is where number one cylinder plugwire connects Problem here for the inexperienced is sometimes the oil pump drive shaft,which seats into the bottom of the distributor shaft,does not line up easily and fights you as you try to seat the distributor into place.

garykocis wrote: Never mind.... I'm twisted up on valve being open/close. I need to look at it fresh tomorrow and check the rotor position as well....

Sounds like a plan

wait a second... don't I have a big problem if both valves are not closed when #1 piston is at TDC???

garykocis wrote: Pictures....

When you took this picture was #1 piston at TDC?

Was the rotor pointing at the #1 plug wire terminal in the distributor cap?

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?

The best picture would be with #1 at TDC then you take the picture of the pointer/balancer

garykocis wrote: 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....

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)?

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).