New guy here,
I have been reading the past Q&A's and trying some ideas. maybe someone has an alternative.
Same old 4000 and dead question....not quite. I have stripped a 13b for a sand rail. It has a new 48 DCOE Weber, It have .42 venturis, .220 air correctors, .170 main jets, .055 idle jets, the new twin coil setup are 45K with 1.5 ohms res. there are no air leaks, good vacum to the advance, oh I changed it over to cap and rotor, all of it. The timmng is on a little past on the leading but i've tried it on the mark also. New everything, new presure sensative fuel pump to. The ignitors seem to work fine also. It will start and idle good, a slow rev to about 4000 is ok, but not a fast rev. at 4K it wont take any more. Any thoughts??

 

If the engine has good compression (no less than 70 psi per chamber), the distributor is advancing properly (vacuum operated), and the carbs are feshsly rebuilt, everything should work. When you floor the accelerator, it should rev from ~750rpm up to 7krpm in just under 1-1/2 seconds.

Now, it's either getting too much fuel or not enough. If you pump the gas, can you get it to rev past 4k? If it does, then it's not getting enough fuel. If no, or it bogs down when you quickly operate the throttle, then it's probably getting too much.

 

Thanks for the info, it sounds like it's getting too much fuel.
Any suggestions on jetting a 48 DCOE for a stock 13B?