Thread: Dead Cylinder
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Old 05-24-2010, 02:54 PM
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Join Date: Nov 2006
Location: Gig Harbor, WA
Cobra Make, Engine: BDR#499 351W with Webers
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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
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