dwell angle / ESA module / idle mixture

[Black as]

Guys
I have a 1988 Bayliner 2250 Capri with a 4 barrel 350 Chev motor with a cobra stern drive. In the past week I have changed plugs,leads and points and setting everything to specifications. The thing is the manual says set the points to .43mm and dwell between 27-31. To get the dwell to 27-31 I have to open the points to .65mm and it runs terrible...... so I reset to .43 and it runs fine, is this normal Or am I over reacting. Also last night I set the mixture screws by turning them all the way in and un-did them equally by 3 1/2 turns and worked from there to obtain as accurate as possible smooth idle, I have it running smoothly at 550 RPM. The question here is I used a tacho and as I kept turning the screw anti clock wise the revs kept building, I would of expected that there was a point the the idle would start to decrease, but this didn't happen So I ended up screwing them back in and wound them out to around 3 1/2 to 4 turns and it idles very nicely again am I over reacting.

Next question is, once I had it running smoothly on the "muffs" in the driveway at around 550 rpm I activated the ESA module by hand but couldn't hear the idle fluctuate or will this only be noticeable in the water under load. Ive done a resistance test and all seems fine module wise.

My next step is to put it in the water and re-check everything again in and out of gear etc

Your thought would be greatly appreciated

 

[88beighlinercapri5.7]

Re: dwell angle / ESA module / idle mixture

You got a lot going on there, good luck. I just wanted to chip in a bit- changing the dwell also changes the timing, so after setting the points you have to reset the advance.

 

[Black as]

Re: dwell angle / ESA module / idle mixture

You got a lot going on there, good luck. I just wanted to chip in a bit- changing the dwell also changes the timing, so after setting the points you have to reset the advance.

Ive done all that but the funny thing is its not to manual specification's and that's what's really got me, don't get me wrong it's now running sweet as on the muffs in the driveway but Ive done it my way

The real test I suppose is when I put it in the water for the first time

 

[bruceb58]

Re: dwell angle / ESA module / idle mixture

If you activate the microswitch by hand, it should stumble the engine. It will be obvious. There are two switches. One is an overstroke switch. Make sure it isn't engaged when you do your test. You only need to press the one switch.

As far as dwell is concerned, make sure you are following the directions on your dwell meter hooking it up. What dwell were you seeing with the gap set to spec?

 

[Black as]

Re: dwell angle / ESA module / idle mixture

If you activate the microswitch by hand, it should stumble the engine. It will be obvious. There are two switches. One is an overstroke switch. Make sure it isn't engaged when you do your test. You only need to press the one switch.

As far as dwell is concerned, make sure you are following the directions on your dwell meter hooking it up. What dwell were you seeing with the gap set to spec?

I didn't hear the engine stumble and only activated the one switch the ESA module, so I did a resistance test and all checked out fine. I read a section that says do the test with your boat in the water, but thought on muffs in the driveway I should hear some sought of change, I connected the tacho and no change in the idle. all the mechanism all work and did the test in neutral

When I set the the dwell to specification the gap on the points were .65mm but the engine wouldn't rev and It back fired, so I closed the point's up to .45mm re-adjusted the timing and ran fine. This is what I don't get, nothing matches the specs that's in the manual

 

[bruceb58]

Re: dwell angle / ESA module / idle mixture

What is your timing set to?

 

[Black as]

Re: dwell angle / ESA module / idle mixture

What is your timing set to?

I have it at 12 deg BTDC and running 98 octane fuel no pinging at this stage but will get a better idea under load

 

[JustJason]

Re: dwell angle / ESA module / idle mixture

I believe base timing should be at either 6 or 8 on that motor. BTDC of course. So you may want to double check it.

Now on to your gap vs dwell issue.

Points gap get's the points close enough so that the engine will run.

But dwell angle is really what your after.

You need to set the dwell with a dwell meter.

No 2 people on this earth are ever going to measure out 0.020 the same, but 2 people should be able to get a meter to read a certain number.

Don't even worry about the points gap, just eyeball it, and then get the dwell right on the money using the meter.

After you get the dwell set, then you set base timing, in that order. After you've set base timing you need to re-check the dwell to see if it moved on you.

 

[Black as]

Re: dwell angle / ESA module / idle mixture

I believe base timing should be at either 6 or 8 on that motor. BTDC of course. So you may want to double check it.

Now on to your gap vs dwell issue.

Points gap get's the points close enough so that the engine will run.

But dwell angle is really what your after.

You need to set the dwell with a dwell meter.

No 2 people on this earth are ever going to measure out 0.020 the same, but 2 people should be able to get a meter to read a certain number.

Don't even worry about the points gap, just eyeball it, and then get the dwell right on the money using the meter.

After you get the dwell set, then you set base timing, in that order. After you've set base timing you need to re-check the dwell to see if it moved on you.

If I set the timing to either 6 or 8 it starts to run rough, remember Im running 98 octane fuel, if I was running a 89 -91 octane I could probably get the timing to 6-9 BTDC

 

[JustJason]

Re: dwell angle / ESA module / idle mixture

You've got it all backwards in your head.

You can run the engine on Bacardi 151 at idle and nothings going to change.

Octane is resistance to spark knock, if your knocking at 600 rpms you have some serious problems my friend. Octane of your gas wether it's 70 or 110 is not going to change what the base timing needs to be. Your engine is smoothing out because your advancing the timing, which in turn is raising the rpms.

Look at it this way. Set everything to spec, the engine is supposed to run correctly if it's set to spec. If it runs like garbage when set to spec then you obviously have another problem (probably fuel related, or an air leak) that you haven't found yet. And you need to do some more troubleshooting.

 

[Black as]

Re: dwell angle / ESA module / idle mixture

You've got it all backwards in your head.

You can run the engine on Bacardi 151 at idle and nothings going to change.

Octane is resistance to spark knock, if your knocking at 600 rpms you have some serious problems my friend. Octane of your gas wether it's 70 or 110 is not going to change what the base timing needs to be. Your engine is smoothing out because your advancing the timing, which in turn is raising the rpms.

Look at it this way. Set everything to spec, the engine is supposed to run correctly if it's set to spec. If it runs like garbage when set to spec then you obviously have another problem (probably fuel related, or an air leak) that you haven't found yet. And you need to do some more troubleshooting.

I will give it a try tonight and see what happens

 

["G"]

Re: dwell angle / ESA module / idle mixture

A very common mistake is that mechanics try to set dwell and timing with the engine running at a high idle. If the distributor weights are swinging too fast they will advance the timing and you will never get the timing right that way. I always pop the point plate and look at those weight springs. More than once I've found them rusted and broken.

Step one is to get the engine running as slow as you can (usually 550-600 is fine). That requires that your carb is working correctly. Next set your dwell angle. If adjustments raised up your engine idle reset it back down and check the dwell angle again.

Next check your timing. AGAIN.... if it raises the RPM's drop 'em back down and recheck your settings. When you are at 8-10* BTC (or whatever the spec sez) and the idle is at 550-600 you're set.

You say your idle screws are set at 3 1/2 turns but turned in they make no change? One more sign you are running at too high an RPM when making adjustments. The Edelbrook 650 4 BBl on my "built" 350 Chev 4 bolt never needed more than 1 1/2 turns out for a smooth idle. Once the timing is set up you should be able to adjust those carbs and it should make a difference as you screw them in.

One more thing; check your vacuum guage. At idle you SH about 20 inches of steady vacuum. Problems with that may have to do with valve adjustments or intake leaks or even too little cam/ too much cam for the carburetor.

Good luck and hope this helps.

 

[Silvertip]

Re: dwell angle / ESA module / idle mixture

You do have the dwell meter cylinder selector set to "8 cylinder" don't you? And you might also want to check to see if the harmonic dampener has spun which will throw timing off. If the engine has ever run-on, a spun dampener is a strong possibility. Doesn't explain the dwell problem but the two can fight each other.

 

[Silvertip]

Re: dwell angle / ESA module / idle mixture

You do have the dwell meter cylinder selector set to "8 cylinder" don't you? And you might also want to check to see if the harmonic dampener has spun which will throw timing off. If the engine has ever run-on, a spun dampener is a strong possibility. While relatively uncommon, the top bushing in the distributor can wear and when it does, the distributor shaft operates in an oval shaped hole rather than a round one. So what happens is you set the points with a feeler gauge but with the engine running the shaft is now in a different orientation and you get a different dwell angle reading.

 

[Black as]

Re: dwell angle / ESA module / idle mixture

A very common mistake is that mechanics try to set dwell and timing with the engine running at a high idle. If the distributor weights are swinging too fast they will advance the timing and you will never get the timing right that way. I always pop the point plate and look at those weight springs. More than once I've found them rusted and broken.

Step one is to get the engine running as slow as you can (usually 550-600 is fine). That requires that your carb is working correctly. Next set your dwell angle. If adjustments raised up your engine idle reset it back down and check the dwell angle again.

Next check your timing. AGAIN.... if it raises the RPM's drop 'em back down and recheck your settings. When you are at 8-10* BTC (or whatever the spec sez) and the idle is at 550-600 you're set.

You say your idle screws are set at 3 1/2 turns but turned in they make no change? One more sign you are running at too high an RPM when making adjustments. The Edelbrook 650 4 BBl on my "built" 350 Chev 4 bolt never needed more than 1 1/2 turns out for a smooth idle. Once the timing is set up you should be able to adjust those carbs and it should make a difference as you screw them in.

One more thing; check your vacuum guage. At idle you SH about 20 inches of steady vacuum. Problems with that may have to do with valve adjustments or intake leaks or even too little cam/ too much cam for the carburetor.

Good luck and hope this helps.

thanks "G" for your comments you were correct never thought of checking the weights in the distributor, they were stuck, a bit of CRC and they are now free and operationg correctly. I reset everything to specifications and she is running very nicley thank you.

BUT,,,,,,, The ESA module isnt working as originally posted at the start, had the revs down to 500 RPM and nothing, used a multimeter and its showing the switch is working but where do I go next, checked and made sure everything was connected and cleaned all the electricall connection and still nothing, the mechanism works fine but did this test by activating by hand.
Any suggestions guys