Dead Cylinder

[Gun Doc]

Jac,

No it is not a crossed wire. My wires are all cut to length and are in looms. The cylinder is completely dead. The electrode insulation is as white as snow.

Gun Doc

[CobraEd]

never heard of this before, but maybe it is a bad (open) plug.


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[Gun Doc]

Ed,

I have tried at least three brand new plugs...

Gun Doc

[Rick Parker]

If you are sure you have spark, with the engine idling screw the mixture screw on the offending cylinder closed, any change(?) then open to 3/4-1 turn open. Any change? Check the air volume draw compared to other cyls. Report back.

[cobred]

It sure sounds like no fuel. I never messed with webers but what if you lightly spray the carb.cleaner in the carb. air horn of the bad cyl. while the engine is running. You should be able to tell if the cyl. starts to fire.
Also, is there any vacuum plug or fitting to that intake port that may be causing a lean miss?

[DanEC]

Originally Posted by CobraEd

Did u check the plug wire? Put an ohm meter on it, it could be open.


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Yeah - I would double check your plug wires. I had a problem like this once and it ended up being a plug wire with intermittent connectivity. It was basically broken at the plug boot. Sometimes it would fire and most of the time it wouldn't and I had a miss. Everytime I shorted out the wire to the block to check RPM drop it would manage to have fire. However, I'm a big fan of Taylor wires and I would be surprised at one of them going bad.

[Gun Doc]

Rick,

I am sure I tried adjusting the mixture screw back when this all started. Turned it all the way in and slowly brought it out to over two complete turns without much, if any change.

One thing I forgot to mention: Today when I put the timing light on the idle momentarily increased by a couple hundred RPM. I first had the light on the bad cylinder, but was not getting a strobe, but did have RPM readout, so I switched to #1 cylinder and got the same thing. Then I figured out how to operate the light (it is a new one!!) and started getting the strobe. So I switched the light back to the bad cylinder. The RPMs increased at both cylinders, but just for a few seconds…

Never seen that happen before. Anyone else heard of it?

Gun Doc

[FWB]

look at the center contact of your msd cap carefully, is the button still there?

if so, then check your voltage to the msd box, they are voltage hogs and if they are not getting enough power they do strange things, i would see what kind of output your alternator is giving you and is the battery up to snuff, where are you getting power from going to the msd.
by connecting the timing light to the bad cly, you introduced a temporary field giving the idle up condition.
the problem seems to be ignition, or power to the ignition.....

[CobraEd]

Is it possible that the intake lobe on your cam is wiped. If so, everything would appear good, but nothing to ignite. ????

I have seen this on one of my Cadillacs years ago. Start the engine with the valve cover off and see if the rockers are moving for that cylinder.


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[SLM]

how about the msd pickup wire to close to the ignition wire, had the same problem

[elmariachi]

Originally Posted by FWB

look at the center contact of your msd cap carefully, is the button still there?

MSDs will deteriorate that carbon button quickly. Mine started missing on one cylinder going down the road and this is exactly what it was.

[Gun Doc]

Thanks to all who have posted here...

I think I found the problem. Rick Parker sent me a message and suggested that I may have a bent throttle plate shaft on the carb that feeds the dead cylinder. I followed his advice and first adjusted the idle speed screw (increased) and then attempted to adjust the idle mixture on the dead cylinder. Once I increased the idle speed, that cylinder started to fire as indicated by a change in RPM when I adjusted the mixture. Prior to doing this, adjusting the mixture screw had no effect on that cylinder (RPM).

I played a little with all the carbs (didn’t disconnect all the linkage) and could get all of the barrels within 1 kg/H of the others. The only one that I could not get close was the “good” barrel on the “bad” carb. This leads me to believe the shaft may be bent.

I will disconnect the linkage and attempt to balance the carbs on Sunday (going to the Good Guys show tomorrow!!). Hopefully I’ll be successful; otherwise I will pull that carb and attempt to “adjust” the shaft.

Thanks to all who offered suggestions! It is great to be able to tap into the welth of experience on this site!!

I’ll keep you all posted as to the final outcome.

Gun Doc

[Gun Doc]

Update...

I attempted to synch the carbs yesterday and after about forty minutes of frustration called it quits for the day. I learned long ago when frustration sets in it is better to walk away and come back with a fresh perspective later.

While attempting to dial in the carbs, I could never get the one feeding the “Dead cylinder” to get within 4-5kg/H of the other three without turning the idle up to around 2000 RPM (had to increase the three good carbs). It was getting pretty hot (not the car, but me!) and I had been working in the yard previously, so my fun meter was pretty much pegged!

Today I thought back on what I had done and how the engine reacted. I also conducted a search of this forum on all things Weber. This was most helpful...I found an old post started by Rick Parker where he had a problem with one cylinder and thought it may be caused by a leaking gasket. It turned out to be a twisted throttle shaft in one of the carbs. It wasn’t what you would think, though. The offending cylinder wasn’t the dead one, but the other one on that carb. It seems the butterfly was open when it should have been fully closed, so to get that carb to fire either cylinder it had to be set too high on the idle side.

I also found a post I made right after I got this car. I had about 300 miles on it when on the way to Austin Texas the throttle started to bind. I could not get more that ¼ throttle out of it. It was the same carb I am having problems with now that was causing the binding.

I got a number of replies to that post, one of which was from Rick Parker who pointed out that my linkage looked like it could cause problems and that I would always have a hard time synching the carbs (which is true).

So, I think my current problem is just a continuation of my initial linkage problem. I also think, like Rick, my one carb is probably “tweaked” and my dead cylinder is not the problem at all. It is the one next to it. I also think, no, I KNOW that I need a better linkage setup.

I know this is starting to read like War and Peace, but I hope maybe it will also help someone, either now or in the future with like symptoms… What I need from you all is some suggestions as to what linkage will work well with 351W.

Here are two things I can’t change:

Cable throttle
My manifold does not have a boss to mount a center bell-crank (does anyone make an adapter plate that mounts between the carbs?)

Any suggestions or photos would be great!!

Thanks,

Gun Doc

[dallas_]

Originally Posted by Gun Doc

My manifold does not have a boss to mount a center bell-crank (does anyone make an adapter plate that mounts between the carbs?)

Any suggestions or photos would be great!!

Thanks,

Gun Doc

I would also like to hear a response to that (and see pics).

[Gun Doc]

Dallas,

I called Inglese last week and spoke to a guy named Chuck Gleaves he was very helpful and got me hooked up with a side/center pull linkage…Only sold me the parts I needed to make the conversion, not the entire kit. He saved me over $175.00. I completed the test fit yesterday and it works great! I have not run the engine with the set up yet, because I need to replace the base gaskets and the old ones will take a while to get off, as they are glued down.

Chuck also had a number of suggestions as to jetting, E-tube sizing, etc. He said it took him about a year to perfect the tune for the 351W. Mine is very close to what he suggested with the exception of E-Tubes. I am running F7s and he suggests F16s. I may change sometime in the future.

I do have photos of the set up, but they are too large to post here. Maybe I can put them in my gallery…

Gun Doc

[dallas_]

Gun Doc,
Thanks for posting the pics. That looks like it could work.
For some reason I was convinced the center pull linkage (mounted in the center of the intake) was the best way to get identical throttle movement on all the carbs but that setup looks like it could work.

Hope that solves your problem.

[Gun Doc]

It’s been awhile since I last posted my progress…

I have finally gotten my linkage sorted out. It works great from what I can tell with the manifold off of the engine. I had to pull the intake due to a bad set of gaskets (Fel Pro 1260) which I am replacing with the steel reinforced Fel Pros (1260-S). I am about to put everything back together.

I am thinking of changing my jetting yet again. Currently I am running .60 Idle, .80 idle holders, 145 mains and 205 air correctors. I am also running F-7 E tubes. I am thinking of going with the F-16 E tubes, since the engine is still very rich on the idle circuit. It seems to run fine on the main circuit.

Chuck at Inglese suggested 65 idle, 1.20 holders, 1.70 mains with 2.25 air correctors along with the F-16 tubes. I have read some say that this combination creates a too lean condition.

I have in my possession .60, .65 and .70 idle jets, .80 and 1.20 idle holders, 1.20 and 2.05 air correctors and F-7 and F-16 E-tubes. The only mains I have are 1.45, but I can easily drill them to a larger size if needed.

My engine is a 351W with AFR 185 heads. Compression is 9.7 to 1, timing is 32 deg. My cam is 573 lift intake, 568 exhaust, duration @ 50 is 244 intake and 230 exhaust with 114 deg lobe separation. I live in Clarksville, TN which is about 500.’

What do the experts say about my jetting???

Thanks,

Gun Doc

[Dwight]

I'm not an expert on anything!

this is a link to a great site about how to read spark plugs

Great pictures

http://members.uia.net/pkelley2/sparkplugreading.html


Dwight

[Gaz64]

Changing your emulsion tube will have no effect on the idle circuit.

The engine can run with the e-tubes removed to find where the end of progression occurs.

[Rick Parker]

Chuck at Inglese suggested 65 idle, 1.20 holders, 1.70 mains with 2.25 air correctors along with the F-16 tubes. I have read some say that this combination creates a too lean condition.

Try his recommendation and make small changes after you determine which system (Idle or Main) needs attention. I agree with the F16's.