Club Cobra - The saga continues or tuning woes

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The saga continues or tuning woes

Hi, I think it easier to rely on the vast amount of knowledge and good faith that exists here than to continue to scratch my head at each step.So,on my current saga I changed out idle jets and holders to reduce the reversion spray over the carbs(48IDAs). I'm still not happy with my linkage ( fabricated it myself) but working on it. Current problem- set the idle screws a little high and tried to read each carb with the air flow device in order to bring them into sync.. One carb stack,in particular, is showing something very odd-I think. The readings on all are a consistent number with a bit of flux-about 5-12 on the scale. The carb feeding cylinder six sucks in a pulse pattern-I mean the needle will literally bounce between 6 and 20 each time the cylinder fires. There is no way I can make any comparisons.I set the mixture screws on all carbs to 3/4 turn off seat. That cylinder, by the way, also exhibits the most upward fuel spray.I thought it just wasn't firing but I checked the wire and plug.Any ideas what I'm seeing here and how to correct it. Thanks for the help, Jon

The bouncing reading of the airflowmeter should not be linked to whatever other problems you mention; bad link, idle secrews or jets. But, it might be linked to the reversion.

My first thoughts are:

- any leakage in the runner (from mouth of air horns down to the valve)?
- is the valve opening correctly? Lift and duration as it should? (worn knocker or whatevever)
- is cylinder vacum and compression pressure correct?

I did have a same kind of problem with 2 x DCOE once, fuel came out of one of the carbs, dripping. I think the solution to this was to connect one vacum line from each runner into a single line for brakes and dist. vacum (although I didn't get to test this). Of the 4 runners, 1 gave vacum to the brakes, 1 to the dist.

So, if you run any vacum lines from that cylinder, that may also be a part of the problem.

RS

Jon,

As Rune has said, if you don't have already add a vacuum port to each runner about -3 AN or -4 AN plumbed into an 8 in/1 out block. You can then plumb your brake booster to the 8 way block.

Can you post a pic or two of your setup?

No vacuum system in play. Mechanical adv.dist. and manifold has no place for fittings( Carbs Direct unit I bought).Could be leaks someplace. I'm learning how sensitive these carbs are to random leaks. I think I'm going to pull a valve cover and see if the lifters are working properly on that side. I can't imagine that only one cylinder got damaged or rings didn't seat properly( new build) but who knows. I'll try to post a picture of the actions tonight. Thanks, Jon

Would you believe it- wires. I thought long and hard about why fuel was spraying up from the stacks but only on three of the carbs. O.k did I forget to put rings on those pistons and other foolish things went through my mind. So I started with the cheap route since I still don't understand Webers- Put on new spark plug wires. voila! spray stopped and erratic bounce to flowgauge stopped.Some pistons just were not firing. I even wondered if the MSD box was doing the "shut down cylinders to avoid over reving but at the idle end by mistake". I feel much better thank you. Now I still need to sink these things.Regards, Jon