<VV> Re: main jet vs idle

[Larry Forman]

Hi Padgett,
Please see comments interspersed in your text.
Larry

At 02:49 PM 11/19/2005 -0500, Padgett wrote:

>The #4 plug stopping firing is bothersome but have seen on rare occasions 
>before a plug that just did not do well at low rpms. Are all W8ACs 
>purchased in September so not many miles. Not entirely comfortable with 
>choice but cheap.
>
>Inspected the #4 plug and other than slight blackening, it looked new and 
>was gapped .035" yesterday when performing compression check. Have not run 
>much since choice is with rattling idler or without fan.

Cheap plugs does NOT mean bad or inferior.  These were specifically 
designed for air cooled cars, so they should be very close to ideal!  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.  You could alternatively swap it into a cylinder that is 
firing well, and see it the issue moves with the plug.


>Now the car has a history of idling well following close attention and 
>then deteriorating so not 100% sure problem is solved. Not having many 
>spares yet is also an issue and slows things down. (Turkey Rod Run is next 
>weekend with Florida's largest swap meet so hope to pick up some essentials).
>
>My Heathkit Ignition Analyzer (1015) is the smaller one and does not have 
>all of the features of the more deluxe units so will have to build a kill 
>board.

Forget the kill board unless you absolutely need another project or just 
want to have a cylinder balance tester.  I got one off ebay for $20 that 
works complete with manual, case, leads, etc..  Alternatively, use a good 
digital tach and a clip lead and straightened paper clip.  The digital tach 
is needed for the resolution of an analog tach will not be enough, unless 
you get the professional cylinder balance meter that does use an analog 
meter but is referenced to the idling rpm and not zero rpms.  Well ground 
one end of the clip lead and connect the other end to the paper 
clip.  Connect the tach and monitor engine rpms when the engine is well 
warmed up.  Pull back 6 rubber distributor nipples from the spark plug 
leads with engine off.  With engine on and idling, write down rpm and short 
one spark plug lead holding the clip lead with insulated pliers.  Write 
down shorted rpm for that cylinder.  Repeat for all six cylinders.  You now 
have all the information a cylinder balance checker will provide.  See if 
one cylinder has the least affect or no affect on rpm reduction.  That 
cylinder is not contributing it's share.  You could even write an Excel 
spread sheet and graph the rpm reduction versus cylinder and save it away 
for comparison another day.

>Plan also to swap ignition wires though these were recently installed by 
>PO and are 8mm Silicone. Is hard to describe in a post but acts like a 
>plug that runs fine for a while, then fouls, and then starts firing again 
>when revved. May try opening idle mixture a touch more but at 2.5 turns 
>already.

This is another good approach.  Same as swapping spark plugs, but not at 
the same time.


>If nothing else, now I know what a smooth idle for a Corvair feels like 
>and have a target.
>
>Padgett