I am pretty well convinced my WOT stumble/bog is not a lean condition, but rather a rich condition. This happens on two different cars with two different Cliff's q-jets. I am @ 5K altitude which I suspect may be a factor. At immediate application of WOT, the 1970 GTO stumbles and kicks out a black puff, then runs like hell. The other car (1968 Firebird) noticably dips in power right after WOT then moves out. I have struggled with this for some time and have posted to this subject in the test and tune to section. This is rich event is backed up by LM-1 wideband readings on both cars (low 9's). I finally just removed the pump linkage and took the Firebird for a drive. This did not introduce any lean stumbles even going to WOT. I was surprised that it ran as well as it did without any pump shot, but I think it further confirms my need to try and reduce the pump shot rather than play with the secondary air valve rates which I've adjusted in the range from about 1/4 turn to a full turn (which makes both of the cars dogs) and haven't gotten rid of the stumble. This makes sense if it is not a lean stumble I am chasing.
So other than using the outer pump level hole, what are my accelerator pump tuning options from here?
On a slightly different topic:
Cliff, my 1970 GTO has a stock carb 7040268 and I remember chatting with you a long time ago and thought you had mentioned it had an APT, but I am not 100% sure. If so, where is the darn thing I couldn't identify its location?
