Missing on inital, then hard accelleration (2.2T)
 

OK I have another request for tuning advice.

My car has developed a popping/missing on initial acceleration, then it will even out and run fine until ~4,000 and then starts to misfire very bad. If you shift up a gear it is fine until the 4,000 mark and starts over. It is very noticeable upon hard acceleration.

Background: This is a 2.2T motor, which I have new wires, plugs, points and coil installed. The distributor is a Marelli and I know the advance weights are moving freely. The cap and rotor look fine and the timing is correct. I was looking primarily at the ignition as the source of the problem but wonder if I am off base. After the installation of the new coil (which I was sure was the cause) the problem is the same. I am worried that it could be a condenser or rotor problem, which I understand are unavailable for the Marelli.

The car has Weber’s with 32MM venturi, 60 idle, 130 main, F1 emulsion and 180 air correctors. I can tell you that all of the accelerator pump shots are even, the float level is correct and all cylinders are pulling equal air at idle and at 3,000. It probably is a little rich with the 60 idle but it runs a lot better than when I had 55's in it.

Is it possible that this problem can come from carb adjustment? Before I go deeper into the ignition, I thought I would ask the experts on Pelican for their thoughts.

Thanks for the assistance.

Keith, I have the same motor and HAD exactly the same problem :)

For my car with the Marelli it turned out to be the points... the spring had lost its tension when I accident crossed coil wires and cooked the system. Turned out the points has gotten red hot and the "springiness" of the points was reduced. Therefore they couldn't keep up over 4000rpm. The fix was new points.

The total fix to my ignition problems has been documented on this board with my upgrade to a Bosch dizzy and Crane XR700.

Email me if you want more or do a search with my name.

Cheers

John

Thanks for the idea. You reaffirmed what I thought, it is ignition. I figured I could not be alone.

Funny, I have a 2.7 distrubutor and after seeing your post, decided it may be time to turn it down to fit.

I have a pertronix in another car and planed to do that to the Bosch. Thanks for the great write up you did on your distributor project. Time to find a good machine shop to turn mine down.

Now for the million dollar question, are points available for the Marelli? I see Pelican lists "Distributor Points, 911 (1969-71)
D-602-226-02" but it does not specify Bosch or Marelli. If I can find points at least I can get some drive time in before snow flies.

Yep, they are definitely available as apparently they are used in a few Fiat/Lancia applications as well. I will try and get you a part number tonight (Australian time) off my Marelli that is still floating around somewhere.

You won't look back upgrading the distributor. Just the anguish you save being able to buy new caps and rotors more than makes up for the initial running around and costs. Glad my post helped.

Cheers