Hi Andy,
I'm new to the mailing list. I don't know what you've tried already, so
forgive me if what I'm about to say seems basic to you.
There are only four possible problems you can have: compression, air, fuel,
or spark.
If it passed a leak down test, we'll assume compression is okay.
We'll assume that it's getting air until the other two possibilities are
investigated.
Fuel is easy to check. Pull off the plug wire, run the engine for a little
while, stop and pull out the spark plug, and see/smell if there's gasoline
on the electrode.
(Before you put the spark plug back in, squirt a little oil into the
cylinder. It will help the rings seal in case the fuel washes them down.)
Spark is also easy to check. Get an extra spark plug, ground the threads
on the block somewhere, connect the #4 plug wire to it, run the engine, and
see if it sparks. (Make sure you have no fuel leaks before attempting this.)
If it passes those tests, check for vacuum leaks. The easiest way to do
that is to spray carb cleaner on your vacuum hoses and fittings while the
engine is running. If there is a leak, it will suck in the carb
cleaner. This will seal the leak briefly, cause the carb cleaner to be
burned, and engine RPM will change. If the PCV valve is connected to a
vacuum port on the #4 intake runner like you say, I would investigate this
area first. Loss of vacuum at the #4 intake runner could cause an
excessively lean air/fuel mixture to be delivered to the #4 cylinder on its
intake stroke. (Also, I would check to make sure that the PCV valve is not
installed backwards, though that usually affects all cylinders by
increasing the pressure in the crankcase and restricting movement of the
rotating assembly, but it never hurts to check.)
If the distributor is off a tooth, it would affect the ignition timing on
all cylinders. Get a timing light and verify ignition timing, though, if
you like. Standard small block Ford ignition timing is usually 6 to 10
degrees BTDC.
The valve train for the #4 cylinder could possibly be at fault, too. Weak
valve springs or worn lobes on the camshaft might be causing the valves not
to open all the way. This could cause a substantial power loss for the #4
cylinder.
That's all I can think of right now. Anyway, I hope this helps, and let me
know how things work out.
- John
B382000703LRXFE
At 11:47 PM 12/29/2001 -0600, you wrote:
>Hi, guys:
>
>Well, it's me again, still with a dead #4 cylinder in my Tiger. On top of all
>the other stuff I've tried, I've now done a leak down test and the cylinder
>held just fine. Everything, and I mean EVERYTHING, appears to operating
>normally but pulling #4 plug wire off while the engine is running makes no
>difference.
>
>I'm at my wits end with this. I have a virgin 260 to build for the car but
>that seems a bit drastic, at least until I know what's wrong with the 289. As
>far as I know, I could spend thousands of dollars building that 260 and still
>have the same problem when it goes into the car, if the problem turns out to
>be electrical. The car just has nothing on the low end and will barely come
>off the line. Could I have the distributor one tooth off? Could hooking the
>PCV line up to the vacuum outlet on the #4 runner on my intake be causing a
>problem? Could I just be jerking myself off here?
>
>Right now, I'm extremely upset with my inability to solve this problem with
>the Tiger. I've never run into anything like this with a small block Ford in
>any kind of car. Anybody want a show car Tiger turned "project car?"
>
>Andy Walker
>B382001600
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