Hey all, long time no post.

Anywho, I've got a holley 4160 600 cfm that I converted to a 4150, using a Autometer wideband A/F to tune. Before my engine rebuild, I had a factory 400 with an Edelbrock intake, I got my primaries dead nuts and my secondaries would open and it would be at about 12.4-12.6. A little rich but almost perfect.

Then I put a rebuilt 400 in, TMI style, and now I'm still dead nuts on the primaries but I'm pegging the secondaries at 10:1, and probably fatter. I've got 68's in the secondaries right now. If I lean it out much more, it'll be leaner than my primaries.

Now for some key info - I did this 4150 conversion on the cheap. I pulled a secondary block off an old carb that came off a moving truck. Had a plug for the PV and idle adjustment screws. Looks the exact same as the metering block holley has for their conversion kit. If it helps any, the block is off a list #7703

Any help would be appreciated!
Dan