Another timing curve question
It might be a long time before I get to a strip (nearest one is over 90 miles away!). But I can watch the wideband while hitting the gas hard enough to open the PV without getting into the secondaries. Or just disconnect and wire the secondaries to the idle stop. If it's going lower than 12.5:1, wouldn't that imply that the PVCRs need to be reduced anyway?
If I take the bowl & block off again, I could measure the idle restrictor too ;)
See what others say. Often the AFR in the begining or right after the gear shift isn't representative of the long pull.
I know I'm not the only one to see that. In fact it recently came up as a question on Speedtalk.
let me get a couple screen shots from my logs, or maybe even some others.
edit: IRFAN screen capture is dead. I'll have to download a new version or something.
The big thing is that comparitive runs are needed before deciding 12.5:1 is the best. It could be 13:1 that runs best. Only way to know is the strip or a dyno.
As far as highway, I know from having it happen that if the primary jets are too lean, the engine will rev and then die, and if you can catch it it will continue surging until you slow down to a speed transition slots provide enough fuel you can drive it. On my car that was jut around 55 - 60 mph in 3rd.
The second thing - and where the wideband can be really useful - is to see if the AFR changes through the rpm range under heavy load/WOT. For example, if when shifting into 3rd it starts at 12.8:1 at 4000 rpm but then starts to run richer or leaner to the top, it probably needs a slight adjustment of the main air bleed.