huge secondary bog

[pdelo]

 I recently purchased a 1981 corvette with a E4ME carb, which was recently rebuilt by a reputable(supposedly) builder. The car starts perfectly, choke works as it should, in fact everything is great until you hit the pedal to open up the secondaries. Then the car falls flat on its face and sometimes backfires through the carb. The secondary air doors seem to have the right amount of tension and all the linkages and dashpots are working as advertised. I checked timing at that's all good. I found out through the owner that when the carb was done, the air horn was replaced due to warpage. I have read that sometimes when the airhorn is replaced that the secondary fuel passages can be misaligned or eroded and allow the secondaries to suck air and not fuel. Is there a way to test or try to prove this and if so, how can it be remedied? Any info anyone could provide would be greatly appreciated. Thanks, Pdelo.

[Cliff Ruggles]

Difficult thing to test sealing between the new airhorn and main casting.

I don't recommend swapping airhorns as the original airhorn and main casting warp at the same rate, and 99.9 percent of the time the airhorn at most just "humps" up a little across the front and needs flatted slightly to re-seal effectively.

Swapping in a completely different part throws that deal out the window, it may not fit well anyplace.

Anyhow, the "bog" and symptoms sound like a lean condition.

The items that effect that going quickly onto the secondaries are the plastic cam, secondary spring (both should always get replaced during rebuilding), hanger height, metering rods being used, secondary POE and choke pull-off release time/link adjustment.

Aside from the cam/spring, all of these items are external to replace or adjust, so the fix is pretty easy......Cliff