 Almost no airflow through Unisyn - what's this mean? |
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| smontanaro |
 Jul 4 2006, 12:09 PM
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#1
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Senior Member  Group: Members Posts: 1,190 Joined: 3-June 05 From: Evanston, IL Member No.: 4,197 Region Association: Upper MidWest  |
My /6 (original 2.0L) idles kinda rich. I decided I'd see if I could do something about it today. Got out my trusty Unisyn and my 8mm wrench. The instructions I have said to set the Unisyn based on the left rear (#6) throat and adjust it so the red ball is about halfway up the tube. Alas, I had to screw the adjuster in almost all the way to get the ball to move at all and the engine didn't stumble at all. I messed with the idle air screw to get it up to the first line (still with the Unisyn's adjuster nearly fully closed). The other throats all seemed to flow enough air to pick the ball up easily, and the obstruction caused by the Unisyn caused the engine to stumble at idle.
That suggests to me that there's something fishy w/ #6. What does it suggest to the experts among you? (IMG:style_emoticons/default/confused24.gif) (Non-experts with wild-ass guesses are welcome to chime in as well... (IMG:style_emoticons/default/biggrin.gif)) Thx, Skip |
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Replies(1 - 10)
| rhodyguy |
Jul 4 2006, 12:17 PM
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#2
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,084 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
something is not allowing the air to be pulled thru the venturi (IMG:style_emoticons/default/wink.gif). do 6s have an individual intake to carb gasket for each cly and the intake to head? vaccum leak is mwag. time for a comp/leakdown test?
k |
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| ClayPerrine |
Jul 4 2006, 12:18 PM
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#3
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Life's been good to me so far..... Group: Admin Posts: 15,501 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille 
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Run a compression test and a leakdown test. I would bet that #6 is really weak on the compression test.
IF that is true..... then brace your wallett..... |
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| rhodyguy |
Jul 4 2006, 12:33 PM
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#4
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,084 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
or maybe a valve that's way out of adj?
k |
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| IronHillRestorations |
Jul 5 2006, 07:56 AM
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#5
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I. I. R. C. Group: Members Posts: 6,724 Joined: 18-March 03 From: West TN Member No.: 439 Region Association: None
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I'd pitch the Unisyn and get a STE. STE airflow meters do not restrict airflow, like a Unisyn, and give a much more accurate measurement.
This doesn't solve your problem though. Make sure you've got spark, fuel, compression in the cylinder that isn't pulling. You may also need a valve adjustment. Regarding valve adjustments, a little loose isn't OK or better than a little tight, dead nuts is what you want. |
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| Joe Ricard |
Jul 5 2006, 09:19 AM
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#6
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Clogged idle jet.
fix the easy stuff 1st. Check for good spark. Check valves then do a compression check. then put it up on jackstands |
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| Aaron Cox |
Jul 5 2006, 11:00 AM
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#7
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
QUOTE(9146986 @ Jul 5 2006, 06:56 AM)  I'd pitch the Unisyn and get a STE. STE airflow meters do not restrict airflow, like a Unisyn, and give a much more accurate measurement. This doesn't solve your problem though. Make sure you've got spark, fuel, compression in the cylinder that isn't pulling. You may also need a valve adjustment. Regarding valve adjustments, a little loose isn't OK or better than a little tight, dead nuts is what you want. couldnt agree more. the snail ones are a ton better than the ball in the tube..... i can get you one locally for about 25 bucks... vs everywhere else on the net for 40.... AA |
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| IronHillRestorations |
Jul 5 2006, 11:28 AM
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#8
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I. I. R. C. Group: Members Posts: 6,724 Joined: 18-March 03 From: West TN Member No.: 439 Region Association: None
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A good trick I've learned for sourcing problems in a specific barrel (3 bbl carbs), is to unscrew the idle jet carrier about a half turn. If the engine stumbles a little then you know the jet is working, if there's no change, that jet is probably clogged.
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| smontanaro |
Jul 5 2006, 01:15 PM
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#9
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Senior Member Group: Members Posts: 1,190 Joined: 3-June 05 From: Evanston, IL Member No.: 4,197 Region Association: Upper MidWest |
QUOTE(Aaron Cox @ Jul 5 2006, 12:00 PM) i can get you one locally for about 25 bucks... vs everywhere else on the net for 40.... Aaron, Thanks. PM sent... Skip |
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| smontanaro |
Jul 5 2006, 01:16 PM
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#10
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Senior Member Group: Members Posts: 1,190 Joined: 3-June 05 From: Evanston, IL Member No.: 4,197 Region Association: Upper MidWest |
Thanks for all the suggestions. It will probably be another 1.5 weeks (at least) until I can do much more with this, but I will start from easy (and cheap) to hard (and expensive) during further diagnosis.
Skip |
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| Trekkor |
Jul 5 2006, 10:49 PM
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#11
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I do things... Group: Members Posts: 7,809 Joined: 2-December 03 From: Napa, Ca Member No.: 1,413 Region Association: Northern California |
Hi Perry! (IMG:style_emoticons/default/wavey.gif)
yes, check the idle jets. i can clean them all in less than 10 minutes. KT |
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