OK, another question for my early 911 friends.

1970 911T Targa is running good but, there is one last issue I am trying to sort out.

Engine is basically stock except for installation of new 84 mm high compression pistons. carbs have recently been rebuild, zenith 40 TIN. venturi is 30, idle jet is 60

When first together, car had a significant stumble at about 3000 rpm. originally started with 115 mains. I installed some larger mains and that went away. 125's in right now. larger mains were a BIG improvement.

so, car pulls well and hard in first and second. at full throttle in third car stumbles around 5000 RPM's. stumbles in fourth at slightly lower RPMs. if i let off gas to 1/2 or 3/4 throttle and reapply, stumble goes away and pulls to higher rpms.

So, what is the problem? bigger mains again? or try 120's?

Marelli distributor with points. new wires, new plugs, new rotor, new cap. float level set. timing set per factory manual.

The real question is what would limit and cause miss at high rpms; too rich or too lean? My guess is i should try 130's...

Why you guys are at it I would love to hear you opinion about the 60 idle jets.

What are some of the set ups being run on similar motors with 30 venturis?