<VV> Re: main jet vs idle

[Padgett]

>   As for the #4 plug intermittently not firing, REPLACE it!  Splurge the 
> $0.99 for a spare plug.  LOL.  It is very conceivable that you might have 
> a marginal plug.

Well the good feeling was shortlived. Am almost beginning to think that 
there is something else going on.

Replaced the odd #4 with a good spare and am now able to identify some 
really odd things going on.
First, it revs nicely but at steady 2000 rpm can feel just a bit of a 
flutter in the exhaust, not a lot more like twice a second.

Second it starts out with a nice 650 rpm idle in D but the longer it runs 
the more often and quicker it just drops to 400 rpm. Smooths out if I open 
the throttle just a bit and then returns to smooth 650 rpm. Idle in N is 
steady at 800 rpm.

Have checked timing often and is rock steady at 14 degrees below 900 rpm.

Pulling plug wires at 800 rpm in N produces a similar minor (under 100 rpm) 
drop from each cyl. Think I really have it well balanced.

When it drops to 400 rpm the engine seems relatively smooth but can pull #3 
and #4 plug (center cyls) wires with no apparent effect.  When #1, #2, or 
#5 are pulled engine stalls. Pull #6 and engine seems to run a little 
better for just a second as if #4 were firing again. Does same when 
reattached. Verified plug wires are in right order.

Have had ignition analyzer in parade mode and is no apparent difference 
between when at 650 rpm and at 400 rpm. But am not entirely sure what I am 
looking at. Assume the bright spot in the spike is where the plug fires.

Right now valves are adjusted while warm running to 1/4 turn from clack. Is 
there any chance this is not enough ? Now that I have separated the bad 
idler noise engine is pretty quiet while running. When covers were off was 
evident the engine is pretty clean with no sludge apparent.

Know the engine is somewhat worn, is some blowby evident and appears to be 
using some oil though excess idling may be a factor. Suspect it is a 74,000 
mile original but compression on all cyl is above 150.

Have learned that just taking apart to see is really not a good idea, at 
least not while the vehicle is still mobile so want to exhaust all 
possibilities before pulling more than the valve covers.

Thanks for listening,

Padgett