Shannon----It would seem that the problem is the #1 carburetor sending
too much fuel to #1 & 2 cylinders. The "lifting" of the air valve such
as you did to test, indicates the mix is way too rich. If you hadn't had
"50 miles" of good performance, it would be tempting to think you had
the wrong needle n this front carburetor. It's necessary to do a
re-check of where you've been....check float level (which shouldn't have
change) and blow thru the float level fuel control valve.
If you are running with an electric pump, be sure pressure isn't more
than 2.5 psi.
Plugs fouled with oil (wet) or fuel (will dry off with air exposure)?
Compare how far out the needle extends from #1 carb air valve, as
compared to either of the other two. Measure thickness of the needles at
widest exposed diameter.
Check intake and exhaust valve clearances on stations #1&2..
If nothing is found in the above, take a hard look at everything that
sends spark to these two plugs. Poor spark = fouled plugs = no change
when pulling these plug wires.
Put a timing light on both #1 and #6 plug wire. Both should show the
same timing.
I don't recognize the piece you found in the photo.
Let us know the conclusion!
Dick
From: shannon.muncy@gmail.com(Shannon Muncy)
Hello, I hope everyone is having a great day!
I've got an interesting problem. I just got through getting my engine
rebuilt (.020 over, 9.75:1 CR, roller rockers, gp2 cam, goodparts triple
ZS carbs (rebuilt) and headers). The cam has bee broken in and the car
has ran pretty strong for about 50 miles. However the day before
yesterday the engine began to miss terribly at all rpms.
Thinking that it was a timing/ignition problem, I swapped my Pertronix
ignition back to points. I checked each plug verify that I was getting a
good spark. No help. I then took out the spark plugs and found that
cylinders 1 & 2 were badly fouled. I replaced the plugs with little or
no effect.
Here is pretty much a run down of the situation:
1. I'm pretty sure my ignition and fuel are OK. The fuel filter
is new.
2. The distributor has been rebuilt. I initially had a Pertronix
ignition, but I replaced them with points/condenser. I further replaced
those with spares, along with cap, rotor, plugs and wires.
3. At idle (or at any rpm really) I have a pronounced miss. If I
take the spark plug wires off of cylinder #1 and/or #2 there is very
little change in idle. If I take the plug wire off any other plug there
is a pronounced degradation in idle quality. So the problem is
definitely with cylinders #1 and #2.
4. If raise the piston on carb #1 (.25in - .50in) the idle
raises by about 500 rpm and the miss more-or-less goes away.
5. The #1 carb is leaking somewhere, but I can't isolate where.
6. I think at this point that the issue is carburetor related,
so I take the #1 carb off and make sure the fuel valve is clean and
checked the float level, all appeared within spec. I reassemble and
test; No change.
7. Interestingly enough, in the float bowl of #1 carb, I find a
small cylindrical piece of aluminum (I think, but it's not magnetic). It
looks like a rounded pellet about 4mm in diameter. Click on this link
for a pic of it:
http://photos.little-lamb.com/displayimage.php?pos=-393
8. Just for kicks, I did a compression test, 150psi across the
board.
Does anyone have any suggestions on what the next step is?
Thanks for your help.
-Shannon
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