Printable Version of Topic

Posted by: smontanaro Jul 4 2006, 12:09 PM

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? (Non-experts with wild-ass guesses are welcome to chime in as well... )

Thx,

Skip

Posted by: rhodyguy Jul 4 2006, 12:17 PM

something is not allowing the air to be pulled thru the venturi . 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

Posted by: ClayPerrine Jul 4 2006, 12:18 PM

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.....

Posted by: rhodyguy Jul 4 2006, 12:33 PM

or maybe a valve that's way out of adj?

k

Posted by: 9146986 Jul 5 2006, 07:56 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.

Posted by: Joe Ricard Jul 5 2006, 09:19 AM

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

Posted by: Aaron Cox Jul 5 2006, 11:00 AM

QUOTE(9146986 @ Jul 5 2006, 06:56 AM)

Posted by: 9146986 Jul 5 2006, 11:28 AM

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.

Posted by: smontanaro Jul 5 2006, 01:15 PM

QUOTE(Aaron Cox @ Jul 5 2006, 12:00 PM)

Posted by: smontanaro Jul 5 2006, 01:16 PM

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

Posted by: trekkor Jul 5 2006, 10:49 PM

Hi Perry!

yes, check the idle jets.

i can clean them all in less than 10 minutes.


KT