Annular boosters on a Tunnel Ram
Here: 100 cfm more with anular and downleg boosters can't beat AFR
Lets look at the log from the dyno session
Making a dyno pull using only primary side of the carb the AFR stayed flat.
Knowing that, then it must be the secondary side causing the AFRs to drift rich and then lean as seen in the log below.
The secondary high speed airbleeds were later reduced from .033 to equivalent of .029" dia. using wires. This was done after the dyno session since I wasn't prepared for that...
However a drag strip run shows a much flatter AFR in 2nd and 3rd gear, staying largely between 13 and 13.5
Now I feel like that carb's MABs are pretty close to where they ought to be. Now I can make jet changes and secondary spring changes, and maybe even small MAB and emulsion changes...
(whatever was happening before 4700 rpm with the higher vac and rich mix is uncertain but I need to make some better passes as I think I lifted a little)
Next example of logging throttle opening without a TPS. (Different carb, different timing, same engine.)
The drop in vacuum is the best indicator here of increased throttle position.
To maintain the vacuum at 16", then 14" etc, required increasing throttle as the rpm increased.
There's really no way to know that just looking at the log.
When I've made tables of mostly steady state driving (removing acceleration and braking as much as possible)
A little show-n'tell in post #11 if your interested.
Here: 100 cfm more with anular and downleg boosters can't beat AFR
Lets look at the log from the dyno session
Making a dyno pull using only primary side of the carb the AFR stayed flat.
Knowing that, then it must be the secondary side causing the AFRs to drift rich and then lean as seen in the log below.
The secondary high speed airbleeds were later reduced from .033 to equivalent of .029" dia. using wires. This was done after the dyno session since I wasn't prepared for that...
However a drag strip run shows a much flatter AFR in 2nd and 3rd gear, staying largely between 13 and 13.5
Now I feel like that carb's MABs are pretty close to where they ought to be. Now I can make jet changes and secondary spring changes, and maybe even small MAB and emulsion changes...
(whatever was happening before 4700 rpm with the higher vac and rich mix is uncertain but I need to make some better passes as I think I lifted a little)
Next example of logging throttle opening without a TPS. (Different carb, different timing, same engine.)
The drop in vacuum is the best indicator here of increased throttle position.
To maintain the vacuum at 16", then 14" etc, required increasing throttle as the rpm increased.
There's really no way to know that just looking at the log.
When I've made tables of mostly steady state driving (removing acceleration and braking as much as possible)
A little show-n'tell in post #11 if your interested.