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  #1   IP: 72.224.159.217
Old 07-07-2011, 11:41 PM
gary randall gary randall is offline
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carburetor question

My engine is stalling out when I throttle down to approaching-the-dock speed.
(I don't have a tach, so I can't be more specific.)
I rebuilt the carburetor recently, but realized only afterward that I probably did not set the float valve to Moyer specifications and sort of guestimated how it was supposed to go.
I have adjusted the needle valve, choke and idle screws, and linkage so that it runs pretty well at every speed except the nice, quiet and smooth just-barely-moving speed that gets you dockside with style and grace.
Could the float valve be a problem here?
One other observation: I can get a little smoother low-RPM performance if I apply a little bit of choke.
Any ideas?
Gary Randall
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Old 07-08-2011, 06:53 AM
smosher smosher is offline
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I would think that the float would effect running the engine at speed and not idle. Maybe the idle is too low. If the engine runs better with the choke then I would think the low speed mix is too lean. Mine is set to 1 1/2 turns out.

I also do not have a tach, but I end up taking the engine in and out of gear when I approach.

Steve
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  #3   IP: 24.136.67.99
Old 07-08-2011, 09:02 AM
Dave Neptune Dave Neptune is offline
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Float?

Gary, I have done some playing around with the float level in the A-4's carb and found it not to be to touchy. Now I was going up and down about a 1/16" and noticed a bit of a diferance at cruise but not much at idle.
First, and this is a guess you are not familiar with "adjusting the idle" of a carburator?
Second, how much do you think you moved the flaot? It is something that needs to be "VERY CAREFULLY" adjusted so you don't comprimise the float when tweaking the "tabs".
Also have you checked the plugs for color and have you set the timing? If the timing is way off the idle performance will also be comprimised. Do you have a tach onboard? Do you have a PCV setup on your A-4?
If the choke is helping a bit it indicates that you are lean as "smoosher" stated. Try turning the idle adjusting (top of the carb) "in 1/4 turn" and see if that helps.
If you can answer the above perhaps we can get you to get things adjusted properly.
The idle of these motors when set even close should be rock solid unless something is amiss.

Dave Neptune
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Old 07-08-2011, 06:52 PM
gary randall gary randall is offline
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Thanks for your replies.
I am going to assume that it is not the float valve, given that a poorly adjusted float valve would more likely affect things at high RPM.
The plugs are pretty good.
So, that leaves timing and idle adjustment.
I believe I did an OK job with the idle adjustment by following the steps in both the Moyer manual the threads I found on the Forum.
The timing, however, I have not given much thought to. Dave, do I need a timing light for that? Or can I just adjust the distributor by hand until it sounds right?
(I do not have a tach on board and no PVC valve.)
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Old 07-08-2011, 07:33 PM
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Quote:
Originally Posted by gary randall View Post
...The timing, however, I have not given much thought to. Dave, do I need a timing light for that? Or can I just adjust the distributor by hand until it sounds right?
(I do not have a tach on board and no PVC valve.)
Gary-
The attached is a simple approach to the timing.
The procedure is described at item #4 about halfway down the document.
You only need a simple 12V bulb with clips to do it.
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File Type: pdf Troubleshooting lack of spark.pdf (13.0 KB, 311 views)
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Old 07-09-2011, 11:08 AM
Dave Neptune Dave Neptune is offline
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Lightbulb Timing?

Gary, setting the timing by "power timing" is about the best way to do it for overall performance.
First be sure the advance mechanism in the distributor is functioning. Then take her out for a spin to get her all warmed up. Then advance the throttle to just above your cruising speed and rotate the dist for the best RPM's. Once you get to that point let her run for a few minutes then try a little fine tweaking to see if you can gain anything else. That's it your done. Although I do have a recomendation that has served me well for many years on many engines, once you have attained the maximum advance performance back the timing off (retard) a "tiny bit" and leave it. This will smooth the beastie out and she will pure for many hours like that with points and forever with the electronic ignition.
You can also develope your own marks and use a timing lite, but frankly I don't think it is worth the trouble .

Dave Neptune
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Old 07-11-2011, 01:36 PM
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OK Dave...which way do you spin the dizzy to retard?
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Old 07-11-2011, 01:54 PM
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Gary,

If you or a friend have a small air compressor you can carefully take the carb apart and spray it liberally with carb cleaner. Remove and lace each jet with carb cleaner as well then hold firmly between your finger tips and blow through the small hole ensuring they are clean and clear.

I've heard of some people having to push a small wire through them (jets) but I have never had to do it using carb cleaner and air.

Reassemble the carb and put it to normal settings and try it. You may have to make a minor adjustment on the mixture but it should work out fine for you. I've had mine apart many times without having to buy any gaskets etc and it works great following a good cleaning.
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Old 07-11-2011, 02:02 PM
Dave Neptune Dave Neptune is offline
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Question What way

Shawn, it's been a long time since I messed with my timing but as I recall clockwise was advance and c-clockwise for retard.

Dave Neptune
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Old 07-11-2011, 02:11 PM
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Unless your Atomic 4 distributor is different than mine, it's da udder way `round.

Now, of course, last time I wrote something here from memory, I got it wrong, but my memory of messing with the timing (which was all of about 2-3 weeks ago) is that the rotor spins clockwise. So rotating the distro clockwise will retard; counter-clockwise advances.

I'm pretty darn sure of that, the more I think about it, because my neighbor and I were twisting the damn thing all over the place to try to get it to work right.

And now that I think about it even more, I'm positive. Consider the firing sequence and where the wires are located on the cap. The rotor definitely turns clockwise. So yeah, turning the distro clockwise retards the spark.
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Old 07-11-2011, 02:25 PM
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Thanks Bill...the way you explained it makes perfect sense. I'll have to write it on there with a Sharpie or something..I tuned it at the dock, but I haven't tuned it away from the slip yet.

It is funny how something so simple is hard to figure when we are sitting here staring at a computer screen instead of having the motor in front of us.
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Old 07-11-2011, 02:58 PM
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Shawn, I did my timing at the dock as well. Is there a difference in doing it under way. I just went by the engine sound and power.
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Last edited by Mo; 07-11-2011 at 03:21 PM.
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Old 07-11-2011, 03:37 PM
Dave Neptune Dave Neptune is offline
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Question What way

Shawn, like I said it's been a long time and I won't argue the point with Bill. I do have an arrow mounted to the alt support so I'll check.

Maurice, yes it will make abit of differance on the water as the load will be consistant to cruising not trying to move something that won't while the engine RPM's are low on the dock lines. It will be pretty close though.

Dave Neptune
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Old 07-11-2011, 03:37 PM
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Quote:
Originally Posted by Maurice View Post
Shawn, I did my timing at the dock as well. Is there a difference in doing it under way. I just went by the engine sound and power.
Not to put words in Shawn's mouth but...

You can do it at the dock or underway.
The idea is to get it up to your ideal cruising RPM and then playing with it.
If you're alone, obviously it's best done while pulling on the dock lines rather than laying down contorted in the engine room while blasting along at 6+ knots without a soul at the helm!
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Old 07-11-2011, 03:44 PM
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Thanks Roadnsky, much appreciated.
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Old 07-11-2011, 03:50 PM
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Quote:
Originally Posted by Maurice View Post
Thanks Roadnsky, much appreciated.
De nada!

Quote:
If you're alone, obviously it's best done while pulling on the dock lines rather than laying down contorted in the engine room while blasting along at 6+ knots without a soul at the helm!
I should have added that in my sailing grounds, especially in the summer months and on weekends, I see that sort of thing all the time.
AND usually at more than 6K!
It's another reason I'm interested in that TURBO A4 everyone keeps discussing...
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