Inliners International Forums General Discussion Engines Carter WCD 2bbl, off-idle flat spot

Anyone here know this carb?

I thought I was good with carbs but this one has been tough. I've got a Carter WCD 2V on my 195.6 OHV AMC six (this is the "old" six, the Nash motor, not the newer one that later went into jeeps etc).

Carb was NOS, I've got it tweaked up about perfectly (100 rpm idle drop, ported vacuum spark, spotlessly clean). All six plugs read textbook-perfect. Power and mileage are great. (OK power is low but that's not the carb's fault :-)

Problem is, I have a very sharp, very brief, flat spot right off idle, of course, just when the clutch is about to fully engage off the line in first of course. It's worse when cold (California cold).

I carefully ran a single strand of copper wire through all the idle passages (didn't ream or score anything) and there's no debris in the bowl, etc. It's been this way through a rebuild.

The main jet needles are adjustable; I've adjusted them dead-stock factory recommendation. Doing some Google "research" some motorcycle forum suggested (for some wildly different carb of course) having the needles raise out of the jets a bit earlier.

I don't know much about the low-mid-range circuits of this carb. Anyone have any experience with it before I go farting around and make a mess? The problem is subtle, and the car is quite drivable; it's been this way for over a year! But I'm about to rally the thing in a month and it's time I got this little annoyance out!

Try switching the ported vaccuum for manifold vaccuum and see if that will cure the bog, there is no advantage to ported vaccuum advance on a non-smog engine.

Tim

Put a timing light on the engine and see if the timing is changing in the idle-1500 rpm range. What happens is a person normally raises the rpm just before they start to let the clutch out. This may be causing the timing to change (advance) a lot. Then when the clutch engages the rpm comes down, the timing retards and you get a hesitation and a dead spot. I've cured this problem several times on stick cars.

Ron

Thanks for the poke -- I should have done that myself! (I'd set it to ported while I was recurving my distro; while I was determining max. mechanical advance I had a lot of static dialed in -- I should have put it back to manifold long ago.)

It helped, but not complete cure. It may be as Ron G. says.

I tweaked up the idle of course after I moved back to manifold vacuum advance, and got my 600rpm idle vacuum back to 19 - 20 InHg.

How did you go about fixing that? Stock distrib on this motor was 4 static, 11 centrifugal degrees, 15 degrees total advance! Vacuum added another 11. I hacked the distributor for +20 centrifugal degrees, running about 5 static.

It's a new distrib (well OK a year old now), a Pertronix Ignitor and epoxy coil. Distrib I recurved for a lot more advance. I did a how-to that's posted in the Technical Tips ("Hacking Delco distributors for more spark advance"), July 08. Still driving on that. http://wps.com/AMC/1963-Rambler-American/Nash-195.6OHV-engine/Distributor/